Alfa Romeo Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Whenever I leave my 73 GTV for a while, it tends to run on 3 cylinders. Its on 40DCOEs and has a 123 distributor.
Tracked it to No2 cylinder and sure enough the plug was black and sooty. Cleaned it up and had to give it a good scrape to get the baked-on crust off. Plug back in - firing on 4 again

My suspicion is that oil is seeping down the valve guides in that cylinder, fouling the plug and then getting baked on. Its been fine all summer when it gets run more regularly. Does that sound like a fair diagnosis? Any suggestions for what else it might be?

Thanks
 

·
Premium Member
Joined
·
13,984 Posts
That could well be the cause. If you just want to treat the symptom then you could make a hotter spark that will be less affected by the fouled plug. Your 123 distributor will fire a coil with a primary resistance as low as 1 ohm. If your current coil is significantly higher - say a round 3 ohms, then you could replace it with a Bosch Red coil which is 1.3 ohms. That will enable you to open up the plug gaps to at least .030". You could also switch to NGK BPR6EIX spark plugs which are less prone to fouling and can operate with larger gaps, but be careful if you adjust the gap as they are relatively delicate.

You should also give the car an "Italian tune up" - get it hot then rev it to 6000 rpm or so in the lower gears. That will burn the gooey stuff off the plugs.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Thanks - am familiar with the Italian tune up!
My impression is that a bit of leakage down the valve guides is one of those things you just live with if its otherwise running OK. Will also check the coil and plugs - the 1-2-3 distributor made a lot of difference both to starting and running but a fresh coil might help

Regards to SC - I spent 3 months in Spartanburg some years ago and by coincidence was watching a programme on music and culture in that part of the world only last night! A long way from Frensham, Surrey, UK...
 

·
Premium Member
Joined
·
13,984 Posts
Regards to SC - I spent 3 months in Spartanburg some years ago and by coincidence was watching a programme on music and culture in that part of the world only last night! A long way from Frensham, Surrey, UK..
I was born and raised in Ormskirk, Lancashire.
 

·
Registered
Joined
·
1,752 Posts
Is the car burning oil enough so that it is noticeable? Was the plug oily or sooty? I don't see those as the same issue. This website has some nice photo comparisons to illustrate my point: Spark Plug Analysis

If your car continues to foul one of its plugs, I might test the ignition cable or at least try switching it to another plug to see if the plug problem moves to another cylinder.
 
1 - 5 of 5 Posts
Top