small block intake manifold

[Jim M.]

On a 69 small block, is there a reason why the middle area of the manifold, where it meets the heads, discolors the paint?

[Joe L.]

Re: small block intake manifold

On a 69 small block, is there a reason why the middle area of the manifold, where it meets the heads, discolors the paint?

Jim------


This occurs on most small blocks, not just 1969. The intake manifold has an exhaust heat cross-over passage. When the heat riser is closed, the exhaust is directed through the cross-over passage to the left side manifold. Even when the heat riser is open some exhaust gas may enter the passage. The purpose of the cross-over is to activate the divorced style choke used for 1966-74 models and to provide heat to the carburetor base to improve fuel atomization.

The exhaust heat inevitably discolors the paint on the intake manifold in the vicinity of the cross-over. It also discolors aluminum manifolds in this vicinity.

[Jim M.]

Re: small block intake manifold

Thanks Joe, that makes sense. Jim