I am fouling the rear two plugs on each side of the engine. The front two appear in good shape but the rear ones are fouling with carbon. I have a 454 with a Torker manifold and 750 Holley carb. I can clean the plugs but they start fouling real soon. Any ideas?

Two ideas come to mind:

1)Valve stem seals, although it is strange it is the two rear cylinders on each side.

2)I've heard of an intake gasket leak sucking oil from the lifter valley. But then again, it is strange it is on both sides.

OF course it could be rings. How many miles on it? Let us know what you find out.

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-Mark
TC# 717
ACES #1641
1967 Chevelle SS396/375 (http://www.chevelles.com/showroom/1BadRat2)
1967 RailVelle (http://www.chevelles.com/showroom/1badrat3.jpg)(Parting out)
1964 Chevelle 283/195
1975 Corvette 396/425 (http://www.chevelles.com/showroom/1BadRat1.jpg) "Wow, that's a mighty strong 350!"
Rat Garage (http://www.chevelles.com/showroom/RatGarage.jpg)

There is no more than 500 miles on this motor since re-build & HEI system upgrade. 38-40 total advance, 10" idle vacuum. COmpression is 48-50 lb on all cylinders, although I did not check the 'bleed off' from each. It runs tight & hard with clean plugs but fouling of all plugs started couple of months ago. I checked and set timing. The carb has had the PV replaced and gas ports cleaned. All plugs continued to carbon until I changed the primary jets from 72 to 68's. Now it looks like only the rear two plugs on each side foul. I might note, even if it is no concern, the engine slopes to the rear slightly. By slightly, I mean about 1/2inch from front to rear. I bought this car in spring of '01. It has always been a little rich and I noticed it 'cutting out' a couple of months later. I
added extra cooling with a larger radiator, electric push fan and a high flow water pump to bring the temp down from 220 to 195 at cruise. Any thoughts & ideas are appreciated.

If at all possible I would temporarily substitute a known good carb, even if too small, and see what happens with the plugs. Also check your ignition thoroughly. Test plug wires with an ohm meter, etc. If it's an HEI, it must have a full 12 volts to the dist to operate well.

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von '69 300 Dlx SS TC #15 ACES #1575
My '69 SS (http://sites.netscape.net/von69ss/homepage)

Go ahead, call me fool! I checked out the HEI coil and found I hadn't re-connected the ground wire to the monting bolt. ALthough I haven't had time to drive arounf much, it appears to idle better. I won't have the verdict until I cruise more to see if the cleaned plugs stay that way. But, would this loss of HEI coil ground result in lower plug voltage?

That's alright, I've heard dumber things before. My friend, after working on his Cougar, forgot to reattach his 4th cylinder to the distributor, drove all around wondering what that sparking noise was he kept hearing. http://www.chevelles.com/forum/smile.gif

You said the engine was just rebuilt 500 miles ago. Chances are your rings haven't seated yet. Did you run the engine and follow a ring break-n procedure? If not, try it. I had a small block that took almost 9 months to stop oil-fouling plugs, but then I made some stupid decisions when I assembled the engine (chrome rings, coated with STP). Put a few thousand miles on the engine before you panic.