66 350hp exhaust manifolds

[Roy H.]

Left side manifold has an A at the end of the part #.(3846558A)
That is inconsistent with what the judging guide says it should have.
Any thoughts would be appreciated. thank You, Roy www.roysrestoration.com

[Peter J.]

Re: 66 350hp exhaust manifolds

Roy,
I brought this question a few years ago and couldn't get a definitive answer then. My original manifolds have the letter suffix on both manifolds and I was in the market for some really nice originals and found them with and without letter suffix codes and I will be curious to see any explanations you get now.
Pete

[Terry M.]

Re: 66 350hp exhaust manifolds

Send a PM to Mark Gorney through the "Members List" button above. Ask him this question and send him a link to this thread. Mark works at what is now called Saginaw Metal Casting -- the source of the exhaust manifolds you are asking about.

If he doesn't know what the letter suffix means, no one does. You have looked in Colvin's series of Chevrolet/Corvette by the Numbers books, right?

[Peter J.]

Re: 66 350hp exhaust manifolds

Terry,
I went back and checked Colvin's "Corvette by the numbers" and found no mention of the suffix on the part numbers. I sure does have a lot of information about the manifolds though.
Thanks for the heads up about, Mark Gorney and I will PM him and if he can help I will post here.
Thanks again,
Pete

[R N.]

Re: 66 350hp exhaust manifolds

The correct casting number is 559. I've seen many with the "A" and some without. My '67 L79 has an "A" suffix.

[Peter J.]

Re: 66 350hp exhaust manifolds

Kurt,
My question was why some manifolds have a letter suffix and some don't. Both my original 559 & 042 do have them. But I as you have seen many with and without, and since most don't (my experience) have a year indicated in the casting date on the back I am curious about specific usage. Did GM use more than one mold at a time or are they chronological in usage.

[William C.]

Re: 66 350hp exhaust manifolds

GM used many molds at one time, the manifolds were not Corvette exclusive items, and Flint was spitting out several thousand engines every Day, all of which had manifolds from Saginaw.

[Peter J.]

Re: 66 350hp exhaust manifolds

Bill,
I know they used more than one mold but how about the parent castings to make the molds, would they use a suffix to denote a new run of molds? There is nothing special about Corvette small block exhaust manifolds as they were used on everything under the sun.

[Mark G.]

[Peter J.]

Re: 66 350hp exhaust manifolds

Thanks Mark, So if I got it right there was a pattern change after 65 and a 66 manifold with an "A" suffix would indicate that. Since I have a late June 1966 car the really nice 042 & 559 manifolds without any letter suffix, I got the great deal on are wrong for this car. I guess I know which manifolds are going to Jerry McNish for coating now.
Terry was right, you sure know your manifolds and you saved me from having to send you a PM.
Thanks again,
Pete

[Jim C.]

Re: 66 350hp exhaust manifolds

Ron,

I have small block 66 (#27592). My exhaust manifold numbers are as follows:

Left side = 3846559A

Right side = 3747042

I can document these manifolds on my car back to 1986.

If it helps at all, I was the second owner of another 1966 small block (#16401) which I bought back in 1983. That car was EXTREMELY original and it also had the exact same numbers on the manifolds, including the "A" on the left side. Hope this helps.

Jim C.