Exhaust manifold date code castings

[Wayne B.]

In my long hunt for decent correct exhaust manifolds the date codes are a smaller "font" size than the part number and I find it very hard to tell any difference in a six from an eight. Is that normal? they both seem to glob up on everything I've seen. What happens in judging?

[Paul Y.]

Re: Exhaust manifold date code castings

Wayne, what year are you asking about? Paul

[Rick S.]

Re: Exhaust manifold date code castings

On a 67 small block the date code is not visible and not judged. Here is a photo of my date codes which I agree, are hard to read. E24 and E25, May 24th and 25th.
Rick

[Wayne B.]

Re: Exhaust manifold date code castings

Well, previous owners of the car (70 LT-1) had decided to make the exhaust all 2 1/2" (along with hurst T shifter, Mickey Thompson valve covers, etc) so they took the original exhaust manifolds off and put 2 1/2" ones on. They used 3797901 and 3797902 manifolds which go on 62-65's I believe but, I don't think these are from a Corvette for a few reasons. One is that there are date codes on the front side, not the back. Another reason is I think those dates may or may not say 84 (1984) and not 64 but I've seen so many bad looking sixes and eights I'm not sure what these are. I'm also not sure if the dates were or weren't on the front sides of manifolds back then because C3's are as far back as i've played with. Also, I understand the 3797901 and 02 were also used on trucks, at least from some digging around on the internet has told me.

I do have a repro of the correct 3932461 for that car that I ordered and just like so many i've seen, even on the one I know I ordered right, the six could pass for an 8.

So, I'm probably going to throw them up on Ebay so I can get a little back and not have to hock the fillings in my teeth to finish this car and don't want to present them as anything but what they are. here's a few pics:

The whole manifold



two different angles on the date code




casting number:

I think if you threw that number nine in the cast upside down and shrunk it you'd see what I'm talking about a six passing for an eight and visa versa

[Wayne B.]

Re: Exhaust manifold date code castings

oh ya, that's the whole batch. Are these Corvette mainfolds or replacements or from something else GM made?