cold engine exhaust gas diversion to carb

[Jack Steele]

Hi guys, I am having some trouble with my 265 V8 engine this year. After having the car sit for 7 months I installed new correct intake manifold. The exhaust gas port into the intake manifold runs so hot that the paint burns off the intake manifold runner. There are no thermostatic exhaust valves between the exhaust manifolds and the exhaust pipe. Is there a diverter valve in the head? What stops the exhauast gas from going to the carburettor after the engine warms up?

Any answer is better then my empty head has at the moment Thanks in advance,

Jack Steele.

55 corvette V8 August car.

[Bill Clupper]

Re: cold engine exhaust gas diversion to carb

Jack, the '57 parts book calls for a "exhaust manifold heat valve" P/N 3725981. this would divert the exhaust gas to the carb during warmup, then open the exhaust to allow the normal dual exhaust flow. The paint will burn off the intake manifold, below the carb over time, but if yours is severe, I'd suspect the engine timing/vacuum advance can on the distributor may not be functionong properly. Those engines used full engine vacuum to activate the vacuum advance, and, with a spec of 13-3/4 degrees of advance in the vacuum can, (times two for crank degrees), they idled with about 31 degrees of total advance. Check that and see if you can't find your problem. By the way, the exhaust gas flows directly against the bottom of the carb on the "WCFB" carb, which doesn't hurt it because of the cast iron carb base. Later aluminum carbs used insulators & Stainless shields to keep the carb whole.