NFB: 327 Intake Gasket Problem?

[e40]

Hey guys..

My Dad was coming back from a car show with his '66 Vette and had to divert to my house after losing a lot of power. It barely made it..

We pulled one plug, (drivers side) and it was fouled pretty badly. I assume the rest are like that..

Upon taking off the air cleaner, we found the passenger side of the intake manifold and the inside edge of the valve cover has some traces of black carbon like soot. This same substance is also coming out the tail pipes. (See pipe pics)

Would this be a problem with the intake manifold gasket?

pix0rs:

[Joe 1320]

Based on what I see, it appears as though the intake manifold gasket is leaking in the area of the exhaust heat crossover. While you are in there, if 100% bone stock isn't a priority, the crossover can be blocked off with some thin stainless steel to help reduce the heat transferred to the manifold. This is good for a few extra horses and an increase in exhaust noise.

[Injuneer]

I had a 300HP 327 in a 63 Impala (although in 63 they were using the Carter AFB). It needed a fairly regular program of WOT/redline RPM excursions to keep the plugs from fouling. If he doesn't want to drive it like that, you might want to move up a step on the plug heat range.

Looks like it may be running rich as well. First check the A/F tune, then select a plug that matches the way it is driven.

And of course Joe already told you about the leak.

[TraceZ]

I agree with you guys. I see two problems here.

1) intake manifold gasket is leaking at the exhaust crossover. I used to have a 350 in an older Camaro that had the same setup, and I ended up blocking those ports off. The mod is visually undetectable and will increase power because the intake manifold will stay cooler. The bottom of the manifold will also be cooler, so oil will be less likely to burn and cake onto it. The gaskets I ordered actually came with little metal fillers to put in the holes.


2) it is running to rich and fouling the plugs. I would try leaning it out first by adjusting the carb and if that didnt fix it completely I'd go to a hotter spark plug. What is the origin of that carb? I assume your dad either ordered it or it came on the car. Is he sure it was setup correctly for that motor? Has it been tuned since it was installed?

It look like it is rich on the passenger side only. The driver side exhaust tip and bumper looks clean. That confuses me because the intake has 2 plenums (upper and lower) and each one runs 4 cylinders, 2 in each bank. If one side of the carb was messed up then the problem would be on 2 cylinders in each bank, not all 4 in one bank.

So, why would the driver side bumper be clean? I'd suggest you pull the rest of the spark plugs and see for sure exactly which cylinders are rich.