Listen to this 👂

[Mad4slalom]

Hi all you c3 afficianados. Can you listen to this clip , I cant decide if it is running on 7 or 8 cylinders as it doesnt pick up smoothly when I rev it. It has only been in and out of the garage as not legally on the road yet so it needs a blast . I did give it a whiff of carb cleaner a month ago and it was better. Maybe I will pull each lead in turn from the distributor to see if one makes no difference , It may be lumpy due to its cam . It is ticking over not much over 500 whereas i thought it was about 800 so thought I may have a fouled plug . Any thoughts or advice appreciated. Thanks

 

[Mad4slalom]

Sorry it didnt attach as a video, will try again

 

[Chuffer]

Hi Mad4 how`s things in sunny St. Ozzell ? Pity you can`t take it out for a run and get her up to temp and then see what happens . I would go through the simple things first . Take all the plugs out and check for condition , gap and cleanliness . Check condition of all plug leads and for good fit on plugs as well as distributor . It`s so easy to miss a loose plug lead connection and at this time of year in cold and damp conditions the slightest weak spark will play havoc . I have mine set up at about 600rpm tick over when hot and 800 always sounds a bit too `racy` , but mine is not a standard engine .

 

[Roscobbc]

A digital thermometer is not too expensive and is alwsys useful for other things. Using one of these to determine individual cylinder temperatures can be a shock at first as certain cylinders will have a tendency to run hotter/colder/weaker/richer than their neighbours. With a modified engine using stock head's and inlet any differences can be magnified. I accepted the fact with my engine that it needed quite a rich idle mixture to idle properly. Yes it would idle at 550/600 but 800 rpm was better and caused less need for throttle 'feathering' before the engine was fully warm. The engine will never really get fully warmed-up in the drive way and will still take
a good 15 - 20 minutes if out driving normally.
The down-side of all this on my engine was that the plugs (despite using a hi-output spark system) would foul-up after a year or so's use and need replacing (more so as much of my useage is urban). As has been said you need to get that out on the road and give it a good blast, blow away the cobwebs and warm the engine right through and see what happens. If you are uncertain about condition of plug leads and ignition components perhaps replace them as part of a longer term maintenance schedule.........?

 

[Mad4slalom]

Thankd

Hi Mad4 how`s things in sunny St. Ozzell ? Pity you can`t take it out for a run and get her up to temp and then see what happens . I would go through the simple things first . Take all the plugs out and check for condition , gap and cleanliness . Check condition of all plug leads and for good fit on plugs as well as distributor . It`s so easy to miss a loose plug lead connection and at this time of year in cold and damp conditions the slightest weak spark will play havoc . I have mine set up at about 600rpm tick over when hot and 800 always sounds a bit too `racy` , but mine is not a standard engine .

thanks both, that is the plan as soon as it is dry for more than a few hours. Hopefully dvla back at work tomorrow so things may progress. Car has no points etc so hoping a fouled plug or as u said a loose lead. Dying to get out on a proper road and like you say get her properly warm , sure it will be fine then

 

[CaptainK]

Another minor thing to check is that the plug leads haven't got trapped up against the exhaust header and are arcing to them etc. Unlikely, but still something to check.

 

[Roscobbc]

Another minor thing to check is that the plug leads haven't got trapped up against the exhaust header and are arcing to them etc. Unlikely, but still something to check.

Good point - on my BB engine No. 3 spark plug was closer that others to the header flange - and it was very susceptable to arcing from spark plug boot........

 

[Forrest Gump]

Good point - on my BB engine No. 3 spark plug was closer that others to the header flange - and it was very susceptable to arcing from spark plug boot........

I’ve had that too, although only noticeable when the engine was under load / acceleration, idle and cruising were fine oddly.

 

[Roscobbc]

I’ve had that too, although only noticeable when the engine was under load / acceleration, idle and cruising were fine oddly.

Exactly the same with mine. This was with original 427 engine. Same with MSD system fitted. Only really figured it when driving at night less the hood - quite obvious then. Wouldn't ordinarily show unless the engine was under significant load.

 

[Mad4slalom]

Exactly the same with mine. This was with original 427 engine. Same with MSD system fitted. Only really figured it when driving at night less the hood - quite obvious then. Wouldn't ordinarily show unless the engine was under significant load.

Thanks all, fired her up today, took a while to keep running and warm up a bit a only 5 deg here. Pulled each lead from distributor in turn , all made a stumble and all sparked when put near the hole again. Of course this doesnt tell me if the plugs are ok , the are quite buried under the shielding so next good day I will pull some leads and look at the plugs. .

 

[Roscobbc]

Thanks all, fired her up today, took a while to keep running and warm up a bit a only 5 deg here. Pulled each lead from distributor in turn , all made a stumble and all sparked when put near the hole again. Of course this doesnt tell me if the plugs are ok , the are quite buried under the shielding so next good day I will pull some leads and look at the plugs. .

Just because they 'spark' now it doesn't follow that they will under load..........

 

[CaptainK]

Good point - on my BB engine No. 3 spark plug was closer that others to the header flange - and it was very susceptable to arcing from spark plug boot........

I got myself some of those spark plug boot protectors. Then realised they wouldn't fit my plug leads as they were the "L" shaped 90 degree spark plug connector type, so I couldn't put the boot connector over it. In the end I wrapped the exhaust header near the plug boots so they wouldn't touch each other and add another layer of insulation.

 

[Mad4slalom]

Just because they 'spark' now it doesn't follow that they will under load..........

Thats right so Next thing is to check plugs for fouling. If

A digital thermometer is not too expensive and is alwsys useful for other things. Using one of these to determine individual cylinder temperatures can be a shock at first as certain cylinders will have a tendency to run hotter/colder/weaker/richer than their neighbours. With a modified engine using stock head's and inlet any differences can be magnified. I accepted the fact with my engine that it needed quite a rich idle mixture to idle properly. Yes it would idle at 550/600 but 800 rpm was better and caused less need for throttle 'feathering' before the engine was fully warm. The engine will never really get fully warmed-up in the drive way and will still take
a good 15 - 20 minutes if out driving normally.
The down-side of all this on my engine was that the plugs (despite using a hi-output spark system) would foul-up after a year or so's use and need replacing (more so as much of my useage is urban). As has been said you need to get that out on the road and give it a good blast, blow away the cobwebs and warm the engine right through and see what happens. If you are uncertain about condition of plug leads and ignition components perhaps replace them as part of a longer term maintenance schedule.........?

thank you, do you recall what the plugs are ?

 

[Roscobbc]

Thats right so Next thing is to check plugs for fouling. If

thank you, do you recall what the plugs are ?

Can't recall what plugs I used on the stock engine - using NGK's on the modded one - and did step-up a couple of heat grades from what engine builder installed (due to the plug fouling) - I'll look later when I go in the garage.

 

[Mad4slalom]

Can't recall what plugs I used on the stock engine - using NGK's on the modded one - and did step-up a couple of heat grades from what engine builder installed (due to the plug fouling) - I'll look later when I go in the garage.

Thanks, I will look at mine too. I have a built motor with street cam 10/1 comp pistons and free flow 803 heads, perf ally inlet and holley650 dp carb btw

 

[Roscobbc]

NGK as per image. I started off with a '9' - that was too cold - have been using a '7' for the last few years - they still foul-up gradually over a period of time - I simply replace every 18 months or so. Didn't want to go to a hotter plug (lower number) in case of potential issues during hi-rev 'testes-out' use........
'Drill-down' into NGK's info and you'll most likely see a suggestion for most engines.....

 

[Mad4slalom]

NGK as per image. I started off with a '9' - that was too cold - have been using a '7' for the last few years - they still foul-up gradually over a period of time - I simply replace every 18 months or so. Didn't want to go to a hotter plug (lower number) in case of potential issues during hi-rev 'testes-out' use........
'Drill-down' into NGK's info and you'll most likely see a suggestion for most engines.....

Thanks roscobbc, interesting , thank you. I will see what is in there . Seeing the fouling on yours I can imagine mine could well be fouled just down to the amount of short periods of start stop activity it has has over the last 2 months as not road registered yet..