Exhaust system

[Twan B.]

Some one told me that i need 2" pipes for my '65 327/300 HP manual 4-speed # Vin 104084 Corvette.(Dec. '64)
I know that the 250 and 300 HP automatic use a 2" system.
Was there a change from 2" to 2 1/2" in early made Corvettes?
Regarding the judging manual it must be 2 1/2".
The LH manifold is # 3846563 and RH is # 3797902. both are 2 1/2".
Are these ## only made for Corvette or did GM used these also for other cars?
Thanks!
Twan #44079

[William C.]

Re: Exhaust system

300hp with 4 speed is indeed a 2 1/2 inch system, Powerglide is the only exception. The manifolds were used occasionaly on other Chevrolet products, and reproductions (although not 100% correct) are also available.

[Twan B.]

Re: Exhaust system

Thanks Bill.
I'm happy to know that i am right about the 2 1/2" manifolds.
How can i see if the manifolds are repro?
Gr. Twan

[William C.]

Re: Exhaust system

The primary difference is in the casting marks along the parting line. I've attached a couple of pictured I took of the ones on my FI car (real) note the rectangular lumps on the top surfaces, both the number of them and the size. Drivers side an pass side are included. The reproductions I have seen vary in both of these characteristics.

[Twan B.]

Re: Exhaust system

Hi Bill.
Thanks for the pics. I'ts a lot of help for me and now i know that i have the correct one's.
Thanks a lot
Gr. Twan