I am looking to either repair or replace my exhaust manifolds on my 64 Cutlass. I've heard that they do not make headers for this year and custom ones might be too pricey. I have a shop that will fix my current manifolds for 70-100 a side. They need to have the studs replaced and he is going to plane the mating surface. Would it be cheaper to just find a set of used one that are in good shape?

 

Absolutely! You could get the Thornton true dual exhaust manifolds for a few dollars more. The gain over stock is questionable but with some smoothing here and there with a grinder, it should be some. Will the Sanderson or Herman shorties not fit these cars? They are almost as compact as manifolds but have 4 either 1 5/8" for Sanderson or 1 3/4" primary tubes going into 3" collectors. The Thornton or any SBO manifolds don't have this. The Thornton manifold simply has a divider at the opening but does have larger 2.25" outlets on both sides.

 

First, header manufacturers USED to make headers for the 64-67 cars with SBO motors. Unfortunately as fewer of those cars are around, these products have been dropped. The problem is that the frame rails on the early cars about about 1.5" narrower than on the 68-72 cars.

Every header manufacturer routes pipes differently, so some manufacturers' headers for the 68-up cars may fit the early chassis. Unfortunately, without first hand experience, this is hard to know.

 

I have the Thornton manifolds on my 67. I had existing dual exhaust to hook up to, so it was kind no of a no brainer. I do have a set of NOS hookers from back in the day, but they won't go on until fall sometime. I know there is little gain over stock, but getting a cleaner look and one less potential exhaust leak was worth it to me.
Tim