Manifold #3846559 Question

[Peter J.]

I am trying to find out when these two manifolds with the same part number (3846559) were in use. My 66 has the lower version with the two indents next to the center dump bolt holes. I have seen both versions on a lot of original cars and would like to replace my badly pitted ones but, want to make sure they are correct. I left the pictures large so the details would more visible.
Thanks

[Joe L.]

Re: Manifold #3846559 Question

Pete-----

I believe that the upper-pictured version of the 3846559 is the one that's correct for your 1966. If it's not exactly correct, it's "more correct" than the one in the lower picture.

The 3846559 was used from 1964 through 1967 for some Corvette and passenger car applications. Then, it was "resurrected" and used again during 1970-71 for some Corvette applications.

You will note that the manifold pictured in the upper of your photo is a GM #3846559. However, the one in the lower photo is a 3846559A. I believe that it's this version of the casting that has the "indents" you're referring to and I think this version came along during the late C2 or C3 era, although I don't know just when. Also, keep in mind that there may be many slightly different versions of the manifold over the entire 64-71 period both as a result of slight casting differences as well as machining differences.

For the most part, I think the only way to know what the EXACT configuration was of the manifolds used on any particular car is to have the known-original manifolds off that car. Then, if replacements are needed, one has to search through the "sea" of used manifolds out there to find another of not only the original casting number, but of the original configuration in all other respects. Would I ever go through this effort? No.

[Rick S.]

Re: Manifold #3846559 Question

Joe,
On my late build 67 , June 16,1967, I have the 3846559A left exhaust manifold
which has a date code of "E25". I believe that translates to May 25. That manifold has the indent.

[Peter J.]

Re: Manifold #3846559 Question

Thanks Joe & Rick. Both my original manifolds have the indents but the part numbers are in such bad shape I can't read them. I want to replace them and send the replacements to Jerry MacNeish for his treatment but I want the correct versions. Picture is of my original manifold (both are in the same shape)

[Rick S.]

Re: Manifold #3846559 Question

Pete,
Can you read the date code on the backside?
Rick

[Peter J.]

Re: Manifold #3846559 Question

Rick,
Dates are as bad as part numbers, if not worse.
Pete

[Rick S.]

Re: Manifold #3846559 Question

Pete,
Have you sand/media blasted them? If not, maybe the numbers will be more legible after blasting them.

Rick

[Joe L.]

Re: Manifold #3846559 Question

Pete-----

Even though the casting number is virtually illegible, if you will note there are definitely 8 characters. This means it has to be the "A" suffix manifold and that's consistent with the "indents".

Apparently, the use of the "A" suffix began earlier than I thought.

[Rick S.]

Re: Manifold #3846559 Question

Joe,
Don't count on mine manifolds to be original, as I am the fourth owner and unsure if they are original to my car. Since I have owned the car, I have discovered many items have correct numbers and date codes but the third owner owned a Corvette restoration shop.

Rick

[Peter J.]

Re: Manifold #3846559 Question

I blasted them about ten year ago - they were too far gone back then. Joe there seem to be more of the manifolds without indents in better shape for sale. I have one of each in a mismatched pair. So I guess I will go with the first nice one I can find. I bought my first set from an engine supplier in middle of the country, who has been buying and selling engines and parts for over twenty years and when I told him the castings didn't match he was unaware that there were different castings. Told me it would be a good article for the Restorer. You will see mismatched pairs for sale on ebay all the time and I wondered if it were possible that the manifolds were made at the same time. But what Joe says makes more sense.
Thanks for the input guys
Pete

[Peter J.]

Re: Manifold #3846559 Question

I'm the second owner and the first was not a car guy so most of the car was unmolested. I have a pair of realy nice mismatched manifolds and if somebody would have said that the manifolds were inproduction at the same time in 1966 I would have put them on. I always try to replace a part with the correct part if it can't be rebuilt
Thanks again,