2.5" exhaust manifolds for a 66

[Dennis B.]

I want to put 2.5" exhaust manifolds in my '66 in preparation for the zz383 stroker motor to be installed. My alternator is on the drivers side because this was an air car and the alternator mounts with help from that manifold. What 2.5" manifolds will work so that I can use the drivers side manifold for the alternator.

[John H.]

Re: 2.5" exhaust manifolds for a 66

See Joe's post in the 2.5" manifold thread down below for the casting that will work for you.

[Joe L.]

Re: 2.5" exhaust manifolds for a 66

Dennis and John-----

Yes, the 1966 conversion to 2-1/2" exhaust with respect to manifolds is exactly the same as the 1967.

For the left (driver) side, the GM PART #3846563 will work perfectly and have the forward end mount that you need for the left side alternator.

For the right side, you can use either the GM PART #3814970 (cast 3797902) or the GM PART #3797901 (cast 3797901) depending which end that you want the unused (for your application) side mount bracket to be on. Or, you can purchase a repro 3797942 manifold without any generator mount.

By the way, for BOTH 1966 and 1967 the 2-1/2" manifold outlet conversion only works if the car is WITHOUT K-19 (air injection reactor system). GM NEVER offered ANY 2-1/2" outlet manifold for cars equipped with K-19.