C1 2 1/2" Rams Horn Exhaust Manifolds

[Christopher R.]

Are 2 1/2" rams horn exhaust manifolds available for '62 Corvettes? Either from Chevy or reproductions? The '62 requires a mounting boss on the RH manifold for the generator.


How much of an improvement is the 2 1/2" over the 2"?


I believe there is a (much) later model Corvette that had 2 1/2" "rams horn" style exhaust manifolds with a center dump outlet point (where the exhaust pipes bolt up). Did Chevrolet design these later manifolds to position that point the same as earlier C1s? Could the stock C1 exhaust system bolt up to these later manifolds without modification?


The original engine in my '62 is long gone. It presently has a late model 350 with 2" exhaust manifolds and an exhaust system that needs replacing. I just hate to spend money and time on low tech/low horsepower solutions. Headers are out of the question.

[Bill W.]

Re: C1 2 1/2" Rams Horn Exhaust Manifolds

Chris,


There are several 2.5" castings that will work for you. Some have been reproduced, check the PARAGON catalog. I don't remember the casting numbers, but you can find left or right mount for the generator, you can also find left or right alternator mount ext. manifolds. If you are willing to switch to an alternator, you may have a larger choice. Bear in mind that some of these manifolds can be expensive, are you sure headers arn't exceptable? You may be able to get a pair of manifolds at a decent price, but be prepared to be willing to switch from a generator to alternator or from left mount to right mount. Good luck, Bill

[Joe L.]

Re: C1 2 1/2" Rams Horn Exhaust Manifolds

Chris-----


2-1/2" outlet exhaust manifolds were not originally used on C1s EXCEPT for 1962 models with 300. 340, and 360 hp engines. However, the 2-1/2" manifolds should be readily adaptable to your installation. The right side manifold, with generator bracket, is GM PART NUMBER 3814970(CASTING #3797902). The left side manifold is GM #3797901(CASTING #3797901). This manifold also will have a forward mounting bracket which will be unused. For a "cleaner" left side installation, you could use the 63-65 FI exhaust manifold which has no mounting bracket. This manifold, CASTING #3797942, is no longer available from GM, though.


The GM #3814970 right side manifold is still available from GM for a current list price of $134.73. The GM #3797901 manifold is also still available for a current GM list price of $80.40. The casting number 3797942 manifold is available in reproduction for about $250.


As far as how much better the 2-1/2" manifolds are compared to 2", I couldn't tell you. However, I can tell you that the 2-1/2" 62-65 exhaust manifolds are the best flowing small block cast iron manifolds that GM ever made for any application.

[Jimmy G.]

Re: C1 2 1/2" Rams Horn Exhaust Manifolds

Unless you have a radical engine in which case 2 or 2.5 wont matter much either, there will be only minimal preformance difference between the two. Spend your money elsewhere and get more "bang for the buck".

[Bill Clupper]

Re: C1 2 1/2" Rams Horn Exhaust Manifolds

As a note to add to Joe's fine recommendation, If you have a '62, the 901-902 pair is the only suitable setup as one side mounts the Generator and the other side mounts the surge tank. I don't know the exact HP, but I think it's worth noting that the only difference in '65 from 250 hp to 300 hp was a bigger carb and 2 1/2 inch exhaust vs 2in.

[Duke W.]

Re: C1 2 1/2" Rams Horn Exhaust Manifolds

Never saw any objective data, but I've read over the years that the 2.5s are noticably better in a high performance application than the 2.0s. They've always been popular with street rodders who didn't want to run headers.


Duke