Classic ignition problems

[Dave Johnson]

Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

[Theo]

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

If it's misfiring on one cylinder that suggests the plug/coil on that
cylinder. If it has a classic distributor then suggests that or the HT
leads.

Or anything perhaps related to moisture in the air intake?

Theo

[Dave Johnson]

On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.

I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

[Dave Plowman (News)]

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

[Dave Johnson]

On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

[Dave Plowman (News)]

Post by Dave Johnson

Post by Dave Plowman (News)
I gave you the method of checking them. If using a DVM is outside your
pay grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.

You do that by a careful visual examination. Any tracking will show. And
you also need to check the connections between the leads and cap etc for
corrosion.

Post by Dave Johnson
And you didn't say what values I should expect when I measure for
resistance.

Because not all makes are the same. Somewhere about 5000 ohms per foot.
Total, including king lead and carbon brush of the order of 30k. But the
idea is to find the faulty one or ones. Which will read very much higher
per foot than the rest.

Post by Dave Johnson
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

If you want to invent and test a new method, carry on. Let us know how it
succeeds.

[Dave Johnson]

On Fri, 11 Jun 2021 10:35:50 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson

Post by Dave Plowman (News)
I gave you the method of checking them. If using a DVM is outside your
pay grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.

You do that by a careful visual examination. Any tracking will show. And
you also need to check the connections between the leads and cap etc for
corrosion.

Post by Dave Johnson
And you didn't say what values I should expect when I measure for
resistance.

Because not all makes are the same. Somewhere about 5000 ohms per foot.
Total, including king lead and carbon brush of the order of 30k. But the
idea is to find the faulty one or ones. Which will read very much higher
per foot than the rest.

That's the bit I needed to know; many thanks.

Post by Dave Plowman (News)

Post by Dave Johnson
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

If you want to invent and test a new method, carry on. Let us know how it
succeeds.

The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

[Dave Plowman (News)]

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.

I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

[Dave Johnson]

On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

I fully agree. It does seem a daft idea just to keep things neat under
the bonnet and like you say, there will be stresses at the entry and
exit points which over time could lead to insulation breakdown I would
imagine - and right up against grounded metal to boot.

[Tim+]

Post by Dave Johnson
On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

I fully agree. It does seem a daft idea just to keep things neat under
the bonnet and like you say, there will be stresses at the entry and
exit points which over time could lead to insulation breakdown I would
imagine - and right up against grounded metal to boot.

The modern way seem to be to move to coil packs and do away with the
distributor and HT leads. If it was my car I’d be researching the cost of
converting to this.

Tim

[Fredxx]

Post by Tim+

Post by Dave Johnson
On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

I fully agree. It does seem a daft idea just to keep things neat under
the bonnet and like you say, there will be stresses at the entry and
exit points which over time could lead to insulation breakdown I would
imagine - and right up against grounded metal to boot.

The modern way seem to be to move to coil packs and do away with the
distributor and HT leads. If it was my car I’d be researching the cost of
converting to this.

On a V8 that can get expensive! There might be limited room above the
plug too.

[Tim+]

Post by Fredxx

Post by Tim+

Post by Dave Johnson
On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

I fully agree. It does seem a daft idea just to keep things neat under
the bonnet and like you say, there will be stresses at the entry and
exit points which over time could lead to insulation breakdown I would
imagine - and right up against grounded metal to boot.

The modern way seem to be to move to coil packs and do away with the
distributor and HT leads. If it was my car I’d be researching the cost of
converting to this.

On a V8 that can get expensive! There might be limited room above the
plug too.

Yaris packs seem to be very popular for conversions. £100 for 8 (or
thereabouts). Of course you’re gonna need other sensors and engine
management systems as well.

Tim

[Cursitor Doom]

Post by Tim+

Post by Fredxx

Post by Tim+

Post by Dave Johnson
On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but unfortunately
I can't use it on my left 'ooker cos the HT leads run through grounded
metal sheaths for most of their routing and access to get a can of
WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal trunking,
but to me, this is simply asking for trouble. The normal way is to keep
them a reasonable distance clear of any grounds, by the use of plastic
spacers, etc. Even more so if the ignition has been upgraded to produce a
better spark.

I fully agree. It does seem a daft idea just to keep things neat under
the bonnet and like you say, there will be stresses at the entry and
exit points which over time could lead to insulation breakdown I would
imagine - and right up against grounded metal to boot.

The modern way seem to be to move to coil packs and do away with the
distributor and HT leads. If it was my car I’d be researching the cost of
converting to this.

On a V8 that can get expensive! There might be limited room above the
plug too.

Yaris packs seem to be very popular for conversions. £100 for 8 (or
thereabouts). Of course you’re gonna need other sensors and engine
management systems as well.

Those plug-top coils don't have a very long service life, though. They
tend to fail far more frequently than the single, distantly-placed
coils. The cost of that could really add up.

[Dave Plowman (News)]

Post by Fredxx

Post by Tim+

Post by Dave Johnson
On Sat, 12 Jun 2021 12:06:58 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
The salt water spray just seems kind of wrong for obvious reasons.
However, it seems to be regularly promoted on US websites. My
variation was intended to be a kinder version of it, but
unfortunately I can't use it on my left 'ooker cos the HT leads run
through grounded metal sheaths for most of their routing and access
to get a can of WD40 in there is impossible.

I'd be looking for problems where the leads enter and exit the trunking.
I know it was once common to run the HT leads in earthed metal
trunking, but to me, this is simply asking for trouble. The normal
way is to keep them a reasonable distance clear of any grounds, by
the use of plastic spacers, etc. Even more so if the ignition has
been upgraded to produce a better spark.

I fully agree. It does seem a daft idea just to keep things neat
under the bonnet and like you say, there will be stresses at the
entry and exit points which over time could lead to insulation
breakdown I would imagine - and right up against grounded metal to
boot.

The modern way seem to be to move to coil packs and do away with the
distributor and HT leads. If it was my car I‘d be researching the
cost of converting to this.

On a V8 that can get expensive! There might be limited room above the
plug too.

With older pushrod engines (like my Rover V8) you can't really use Coil on
Plug because of the heat from the exhaust manifold. But there are
individual smart coils where you use a short plug lead to them, so can be
situated anywhere convenient.

But I'm using wasted spark. One coil per pair of cylinders, and only needs
a crank trigger. Ford EDIS was an early type and still works well as it is
virtually bomb proof. It is pretty well maintenance free. But does need an
ECU to control the advance curve.

[Fredxx]

Post by Dave Johnson
On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.

The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves. If you hear
the 'tick' from the spark jumping the gap you know it's the plug or
something more serious.

If you can't decipher which cylinder it is then I would pursue the
mixture/carburation route.

[Peter Hill]

Post by Fredxx

Post by Dave Johnson
On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya  permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.
The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves. If you hear
the 'tick' from the spark jumping the gap you know it's the plug or
something more serious.
If you can't decipher which cylinder it is then I would pursue the
mixture/carburation route.

Salt water is not a good idea. Nor is WD40 or any other can filled with
propane if there is any sign of external sparks.

My car was left at Heysham docks for a long weekend when I went to the
Manx GP with a friend. Got back to it and it wouldn't start, everything
under the bonnet was damp. Towed it out off the docks using the van.
Eventually it started firing on one or 2. Popped the bonnet and my mate
sprayed the sparks with WD40. Though the gap at the back of the bonnet I
saw the look of surprise his face as the can of WD40 turned into a
veritable flame thrower. The flame was about 6ft long and lit up the
night really well.

[Fredxx]

Post by Peter Hill

Post by Fredxx

Post by Dave Johnson
On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya  permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and
distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.
The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves. If you
hear the 'tick' from the spark jumping the gap you know it's the plug
or something more serious.
If you can't decipher which cylinder it is then I would pursue the
mixture/carburation route.

Salt water is not a good idea. Nor is WD40 or any other can filled with
propane if there is any sign of external sparks.
My car was left at Heysham docks for a long weekend when I went to the
Manx GP with a friend. Got back to it and it wouldn't start, everything
under the bonnet was damp. Towed it out off the docks using the van.
Eventually it started firing on one or 2. Popped the bonnet and my mate
sprayed the sparks with WD40. Though the gap at the back of the bonnet I
saw the look of surprise his face as the can of WD40 turned into a
veritable flame thrower. The flame was about 6ft long and lit up the
night really well.

A good lesson for all.

I recall when cans were filled with CFCs, you didn't have the problem of
flammability.

[Dave Plowman (News)]

Post by Peter Hill
My car was left at Heysham docks for a long weekend when I went to the
Manx GP with a friend. Got back to it and it wouldn't start, everything
under the bonnet was damp. Towed it out off the docks using the van.
Eventually it started firing on one or 2. Popped the bonnet and my mate
sprayed the sparks with WD40. Though the gap at the back of the bonnet I
saw the look of surprise his face as the can of WD40 turned into a
veritable flame thrower. The flame was about 6ft long and lit up the
night really well.

Friend was carrying out a compression check on an early injection engine.
Which runs the fuel pump with the starter motor. Dizzy ignition.
With all the plugs out, a spark occurred somewhere and ignited the mixture
being pumped out of the spark plug holes. He's in the US, and it was 'his'
mechanic carrying out the test.

[Dave Johnson]

Post by Fredxx
I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.

That was NOT my idea, though! I came up with the WD40 variant (which
I"ve since binned as a result of the flamethrower post).

Post by Fredxx
The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves. If you hear
the 'tick' from the spark jumping the gap you know it's the plug or
something more serious.

Indeed, yes. Another brainwave I've come up with is to record the
sound from the exhaust. The problem with V8 engines is that it's
possible to have them running on only 7 cylinders without knowing it.
So I thought about setting up a laptop running Audacity (or whatever
other you please sound recording app) next to each of the exhausts in
turn (2 in total in my case) and then view the graphical results
expanded in the timeline so all the pulses are visible. In this way
any regular or irregular loss of a cylinder would be easy to spot and
hopefully trace to the cylinder responsible. The addition of a piece
of tracing paper taped as a flap over the exhaust outlet would perhaps
improve the sound level and crispen-up the pulses.
Having said that, I do have a habit of coming up with overly
complicated solutions with a less than stellar success rate. But hell,
I'm not short of imagination!

[Dave Plowman (News)]

Post by Dave Johnson
Indeed, yes. Another brainwave I've come up with is to record the
sound from the exhaust. The problem with V8 engines is that it's
possible to have them running on only 7 cylinders without knowing it.

A standard 90 degree V-8 has a burble due to irregular firing intervals.
But with a cylinder down, it sounds very different.

Post by Dave Johnson
So I thought about setting up a laptop running Audacity (or whatever
other you please sound recording app) next to each of the exhausts in
turn (2 in total in my case) and then view the graphical results
expanded in the timeline so all the pulses are visible. In this way
any regular or irregular loss of a cylinder would be easy to spot and
hopefully trace to the cylinder responsible. The addition of a piece
of tracing paper taped as a flap over the exhaust outlet would perhaps
improve the sound level and crispen-up the pulses.
Having said that, I do have a habit of coming up with overly
complicated solutions with a less than stellar success rate. But hell,
I'm not short of imagination!

A well designed twin pipe system will have a balance pipe between them. To
even out the extraction effect. But even without, all you've done is half
the choices.

A decent rev counter will show which cylinder is poor by unplugging each
plug in turn, and noting the engine speed. But you should be able to hear
this anyway.

[Fredxx]

Post by Dave Plowman (News)

Post by Dave Johnson
Indeed, yes. Another brainwave I've come up with is to record the
sound from the exhaust. The problem with V8 engines is that it's
possible to have them running on only 7 cylinders without knowing it.

A standard 90 degree V-8 has a burble due to irregular firing intervals.
But with a cylinder down, it sounds very different.

Post by Dave Johnson
So I thought about setting up a laptop running Audacity (or whatever
other you please sound recording app) next to each of the exhausts in
turn (2 in total in my case) and then view the graphical results
expanded in the timeline so all the pulses are visible. In this way
any regular or irregular loss of a cylinder would be easy to spot and
hopefully trace to the cylinder responsible. The addition of a piece
of tracing paper taped as a flap over the exhaust outlet would perhaps
improve the sound level and crispen-up the pulses.
Having said that, I do have a habit of coming up with overly
complicated solutions with a less than stellar success rate. But hell,
I'm not short of imagination!

A well designed twin pipe system will have a balance pipe between them. To
even out the extraction effect. But even without, all you've done is half
the choices.
A decent rev counter will show which cylinder is poor by unplugging each
plug in turn, and noting the engine speed. But you should be able to hear
this anyway.

Funny, those were my precise thoughts too. An eye on the rev counter
should be sufficient to see the change.

I have known someone have a faulty ignition lead on his Rover V8 and not
know about it for months. He was an artist whose job was to airbrush
celebrity photos.

[Dave Plowman (News)]

Post by Fredxx
I have known someone have a faulty ignition lead on his Rover V8 and not
know about it for months. He was an artist whose job was to airbrush
celebrity photos.

Yup. They don't tend to run rough like a four cylinder does when you lose
a cylinder. Just down on power.

[Cursitor Doom]

Post by Fredxx

Post by Dave Johnson
On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.
The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves.

Or no gloves at all. Then if you cop a belt you'll know the
insulation's duff on that lead/cap.

[Fredxx]

Post by Cursitor Doom

Post by Fredxx

Post by Dave Johnson
On Fri, 11 Jun 2021 00:58:47 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I gave you the method of checking them. If using a DVM is outside your pay
grade just by new ones. ;-)

yes, but that's not going to show up any insulation breakdown, though.
And you didn't say what values I should expect when I measure for
resistance.
I guess the reverse of the spraying salt water idea would be spraying
with WD40. Use salt water if the air is dry and warm when you test;
use WD40 when it's cold and damp. In the first instance, listen for
misfiring when you spray and in the second, listen for any misfiring
clearing up when you spray.

I think you get the impression DR is not impressed with your idea. The
idea of spraying salt water over high voltage electrics sound perverse.
The stock way to check for a faulty plug or HT lead is to manually
remove them one at a time. Ideally using decent dry gloves.

Or no gloves at all. Then if you cop a belt you'll know the
insulation's duff on that lead/cap.

Are you a masochist? :-)

[Dave Plowman (News)]

I'm wondering if the leads being in trunking makes them very difficult to
do a visual check on. Making them all the more likely to be the source of
the problem, if difficult to change. ;-)

[Cursitor Doom]

On Sun, 13 Jun 2021 00:31:34 +0100, "Dave Plowman (News)"

Post by Dave Plowman (News)
I'm wondering if the leads being in trunking makes them very difficult to
do a visual check on. Making them all the more likely to be the source of
the problem, if difficult to change. ;-)

Asking for trouble on multiple levels. A better idea if neatness was a
consideration was to use those rubber spreaders, then it's simple to
inspect the leads and remove them for easier testing if suspect.

[newshound]

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I've certainly done the "lightning" check successfully in the dim and
distant past on British 4 cylinder cars. I think salt water would be
asking for trouble, but WD40 makes more sense. You could also often
detect leakage by touching a lead or plug cap.

The classic way to find which cylinder was not firing (e.g. because of a
fouled plug) was to remove the plug caps one at a time and see which one
did *not* cause the tickover to collapse. Usually best to do this by
unclipping the plug caps and letting them rest on top of the plugs.

Of course if you go right back to the days *before* plug caps, where
each plug had an exposed screw terminal, you could short these out one
at a time with a screwdriver resting on the block, or with an "earthed"
screwdriver.

[alan_m]

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I can remember cars of a certain age having carbon(??) core HT
suppression leads and after a few years caused all sorts of starting
problems in damp or cold weather. The starting problems were cured with
a simple change to new copper core leads.

[Ian Jackson]

Post by alan_m

Post by Dave Johnson
On 09 Jun 2021 18:37:22 +0100 (BST), Theo

Post by Theo

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).

Does it have individual coil packs, or a classic coil and distributor?

The latter.
I recall from somewhere it's possible to check the HT leads by
watching the running engine in the dark with the hood up and check for
any visible sparks around the leads. Someone else suggested spraying
salt water over the leads while it's running AFTER having run long
enough to idle smoothly. Not sure what you lot think about those
ideas?

I can remember cars of a certain age having carbon(??) core HT
suppression leads and after a few years caused all sorts of starting
problems in damp or cold weather. The starting problems were cured with
a simple change to new copper core leads.

IIRC, carbon impregnated HT leads were introduced because they were
better at suppressing radio interference than resistive plug connectors
(or using individual series resistors).

Having a high-resistance (or even open-circuit) HT lead can have
knock-on effects. I recall that in one of my cars the shortest lead went
almost O/C, with the subsequent misfiring problems. As the coil could
not deliver a spark across the plug gap, the spark chose instead to
track between the coil HT terminal and the 'LT' spade terminal. This
carbonised the insulating material, and I still had tracking problems
after I had replaced the faulty lead. As a 'temporary' fix (until I got
a new coil) I sawed a chunk out of the insulation, and filled it with.
The fix became permanent, and I never used the new coil.

[Dave Plowman (News)]

Post by alan_m
I can remember cars of a certain age having carbon(??) core HT
suppression leads and after a few years caused all sorts of starting
problems in damp or cold weather. The starting problems were cured with
a simple change to new copper core leads.

Replacing carbon string leads with copper is an absolute no-no. The
ignition system is designed to work with a total resistance between coil
and plug of about 30,000 ohms. And that's before you blot out surrounding
TV etc reception with the interference it would generate. And on a modern
car, that interference can also zap the engine management.

Suppressor leads using conductive plastic rather than carbon string have
been around for many a year now, and have a very long life.

[Dave Plowman (News)]

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

A few points.

Older plug leads (carbon string) can fail. Examine them carefully for
signs of cracking. Measure their resistance (they are so much per foot, so
will vary by length) But a faulty one will be very much higher per foot.
Don't forget to check the king lead too.

While the leads are off, look for signs of corrosion where they plug in.

If replacing, get a decent quality conductive plastic type. Bosch, for
example. No need to buy expensive snake oil ones.

Examine the cap and rotor arm for damage and tracking. And note many
replacements are pretty poor quality. Same applied to the ignition amp, if
it has one.

[Fredxx]

Post by Dave Plowman (News)

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

A few points.
Older plug leads (carbon string) can fail. Examine them carefully for
signs of cracking. Measure their resistance (they are so much per foot, so
will vary by length) But a faulty one will be very much higher per foot.
Don't forget to check the king lead too.
While the leads are off, look for signs of corrosion where they plug in.
If replacing, get a decent quality conductive plastic type. Bosch, for
example. No need to buy expensive snake oil ones.
Examine the cap and rotor arm for damage and tracking. And note many
replacements are pretty poor quality. Same applied to the ignition amp, if
it has one.

In the 'good ole days' I would typically pull leads off spark plugs to
find the offending cylinder.

If random misfiring I would suspect mixture rather than ignition.

[newshound]

Post by Dave Plowman (News)

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

A few points.
Older plug leads (carbon string) can fail. Examine them carefully for
signs of cracking. Measure their resistance (they are so much per foot, so
will vary by length) But a faulty one will be very much higher per foot.
Don't forget to check the king lead too.
While the leads are off, look for signs of corrosion where they plug in.
If replacing, get a decent quality conductive plastic type. Bosch, for
example. No need to buy expensive snake oil ones.
Examine the cap and rotor arm for damage and tracking. And note many
replacements are pretty poor quality. Same applied to the ignition amp, if
it has one.

+1

[Abandoned_Trolley]

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

I am assuming that theres a capacitor inside the distributor, and that
its been checked, although I can find no mention of it anywhere in this
thread.

AT

[Roger Mills]

Post by Abandoned_Trolley

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya  permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

I am assuming that theres a capacitor inside the distributor, and that
its been checked, although I can find no mention of it anywhere in this
thread.
AT

I presume that no-one has fiddled with the ignition wiring recently?
About 30 years I had a car which was factory fitted with a 9v coil, fed
through a ballast resistor. When the starter motor was operated, the
resistor was by-passed to give the ignition a bit more oomph.

I had some work done by a garage who reconnected the wires in such a way
that the resistor was always out of circuit. With the full 12+ volts
going to the coil all the time, the engine misfired profusely - and
wrote off the coil *and* the points in short order.

That couldn't be the OP's problem could it?

[newshound]

Post by Roger Mills

Post by Abandoned_Trolley

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya  permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

I am assuming that theres a capacitor inside the distributor, and that
its been checked, although I can find no mention of it anywhere in
this thread.
AT

I presume that no-one has fiddled with the ignition wiring recently?
About 30 years I had a car which was factory fitted with a 9v coil, fed
through a ballast resistor. When the starter motor was operated, the
resistor was by-passed to give the ignition a bit more oomph.
I had some work done by a garage who reconnected the wires in such a way
that the resistor was always out of circuit. With the full 12+ volts
going to the coil all the time, the engine misfired profusely - and
wrote off the coil *and* the points in short order.
That couldn't be the OP's problem could it?

In my youth you sometimes found 6 volt coils with a ballast. But there
were (just about) 6 volt cars still around in those days, and I never
owned a 12 volt motorcycle.

[Dave Plowman (News)]

Post by newshound

Post by Roger Mills

Post by Abandoned_Trolley

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

I am assuming that theres a capacitor inside the distributor, and that
its been checked, although I can find no mention of it anywhere in
this thread.
AT

I presume that no-one has fiddled with the ignition wiring recently?
About 30 years I had a car which was factory fitted with a 9v coil, fed
through a ballast resistor. When the starter motor was operated, the
resistor was by-passed to give the ignition a bit more oomph.
I had some work done by a garage who reconnected the wires in such a way
that the resistor was always out of circuit. With the full 12+ volts
going to the coil all the time, the engine misfired profusely - and
wrote off the coil *and* the points in short order.
That couldn't be the OP's problem could it?

In my youth you sometimes found 6 volt coils with a ballast. But there
were (just about) 6 volt cars still around in those days, and I never
owned a 12 volt motorcycle.

Think most recent ones are 9v. On the principle that if the battery volts
dropped below 9, it is probably too clapped to turn the starter.

[AJH]

Post by Dave Plowman (News)
Think most recent ones are 9v. On the principle that if the battery volts
dropped below 9, it is probably too clapped to turn the starter.

It's more that the internal resistance of the battery when the starter
is pulling a few hundered amps from the coil to around 9V. V8 landrovers
had such a dropper but I though 6V coils.

[Dave Plowman (News)]

Post by AJH

Post by Dave Plowman (News)
Think most recent ones are 9v. On the principle that if the battery volts
dropped below 9, it is probably too clapped to turn the starter.

It's more that the internal resistance of the battery when the starter
is pulling a few hundered amps from the coil to around 9V. V8 landrovers
had such a dropper but I though 6V coils.

Bit wasteful having to drop the voltage more than needed using a power
resistor?

It could be early cold start systems use a 6v coil because they were a
standard item. But once common makes sense to use one designed for the job.

[Fredxx]

Post by Roger Mills

Post by Abandoned_Trolley

Post by Dave Johnson
Hi,
I have an American V8 that I bought 2 months ago. It's been as smooth
as a baby's bum up until today which was the first time I took it out
on a cool, damp day. It misfired from the very first moment it was
running and took about 40mins before it cleared up and run properly. I
can only think of something from the past where I once had issues with
damp in the ign system: distributor cap and HT leads to the plugs. But
what's the proper solution? Preferablya  permanent one (assuming my
guess is accurate about the cause but I really cant see what else it
could be).
cheers,
Dave,
Dagenham UK.

I am assuming that theres a capacitor inside the distributor, and that
its been checked, although I can find no mention of it anywhere in
this thread.
AT

I presume that no-one has fiddled with the ignition wiring recently?
About 30 years I had a car which was factory fitted with a 9v coil, fed
through a ballast resistor. When the starter motor was operated, the
resistor was by-passed to give the ignition a bit more oomph.

Fords used this technique. The spark was marginal when cold and a
consequence was that the engine died as soon as you let go of the starter.

Post by Roger Mills
I had some work done by a garage who reconnected the wires in such a way
that the resistor was always out of circuit. With the full 12+ volts
going to the coil all the time, the engine misfired profusely - and
wrote off the coil *and* the points in short order.
That couldn't be the OP's problem could it?

The OP seems to have abandoned this thread so we'll never know.