Does anyone know how close to original the reproduction manifolds for 1956 Corvettes are? I am referring to the "557" and "558" manifolds that are available from Paragon. Can you tell the difference between these reproductions and the originals when they are installed on the car?
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Re: 1956 Corvette exhaust manifolds
Paragon has undergone a number of changes since they first began reproducing exhaust manifolds. Each time they've gotten feedback and gone to order new stock various parts have improved and gotten closer to originals....
I can't speak directly to the question you ask about the '56 parts. But, why not consider getting the real McCoys? You'll find that many parts are NOT Corvette only. Zora's budget was limited. He didn't tool just for fun. Typically, custom tooling was limited to styling/performance issues.
On manifolds, what other Chevy vehicles had a need for low restriction 'hot' low end torque? Answer, trucks! They had a need for crisp low end pulling performance.
My guess is if you stroll the scrap yards in your area looking at Chevy/GMC trucks from the era (don't count out the school bus), you'll find what you're looking for at almost dirt cheap prices! -
Re: 1956 Corvette exhaust manifolds
First, let me start by saying that my area of expertise, if I possess any at all, is not in the area of solid axle cars. However, several years ago I had some experience with the particular manifolds you seek. It seems that a cousin of a friend of mine was looking for a pair of these manifolds to complete the restoration project on his '56. My friend decided to accompany me on my annual excursion to the Bloomington Show for the partial purpose of finding a set of these manifolds. We looked high and low for them and found none. No one even knew of anyone who might have a pair. Finally, in desperation, I told my friend that it now seemed like the time to bite the bullet and make inquiry of the folks at Piper's Corvette. When they told us that they didn't have any, hadn't seen any in years, and didn't know where to get any, I knew that Dennis was in trouble.
It seems that these manifolds had a structural weakness in that they had a thin casting cross-section in the throat area. Consequently, many of the few that were ever made cracked and were discarded. That is the reason for the acute shortage of originals. However, at that show we talked with Paul Baker of Goat Hill Classics. Paul told us that he was tooling up to reproduce these manifolds but it was an expensive process. He expected to have them available in a year or two. Sure enough, the following year Paul introduced these manifolds at the Bloomington show. I inspected them and they looked great to me. Paul even mentioned that he had eliminated the weakness of the original design by increasing the casting thickness in the throat area. However, to avoid even the slightest external difference, he slightly reduced the internal size of the throat area to achieve the increased thickness. Of course, this might have some effect on performance, but the effect should be negligible. And, if one's concern were performance and not originality, I'd suggest using the later 2-1/2" outlet manifolds.
I believe that Paragon sells Paul's reproductions, but I don't know that for sure. If you're interested, I suggest calling Paul. I haven't got his number handy, but his firm is called Goat Hill Classics and is located in Long Beach, California. Paul is also known as "The Pulley King".In Appreciation of John HinckleyComment
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Re: 1956 Corvette exhaust manifolds
Ed, I recall some repro manifolds had generous grinding marks on the top seam where the molds for the part came together. This area may be improved, I don't know. I looked at my 557 & 558 manifolds and there is no grinding whatever at the seam. There are, what I would call 6 fingers about 1/8" wide and 1/2" long that were mold runners for the iron. These fingers were broken off when the runner was separated from the manifold. Also there is a date code on the inside of each manifold, hard to see, but you know how evil '56 Judges with mirrors can be!! My guess would be that a repro manfold seen beside an original, the subtle differences would be detectable. Personally I'll give a lot of credit to anyone who will make the $$$ investment, such as manifolds, for our hobby.Comment
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Re: 1956 Corvette exhaust manifolds
These manifolds were only used on late 56 Corvettes and 56 passenger cars equipped with two four barrel carbs. That means not many were used. Originals are almost impossible to find, and very expensive when you find them. I have only seen one manifold available since I have been going to swap meets (not even a pair, a single manifold).Comment
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