1966 Exhaust Manifold #'s

[Erv M.]

In the judging manual it explains the part number and the dating on the underside of the manifold which you cannot see when installed. My question on a 384659 it denotes "RH" for right hand followed by two numbers. What if anything do these two numbers denote?

If they are applicable what should I be looking for in an November 65 built car?

[Joe L.]

Re: 1966 Exhaust Manifold #'s

In the judging manual it explains the part number and the dating on the underside of the manifold which you cannot see when installed. My question on a 384659 it denotes "RH" for right hand followed by two numbers. What if anything do these two numbers denote?

If they are applicable what should I be looking for in an November 65 built car?

Erv------


I believe those numbers represent a pattern number. A pattern is the device used to make the sand molds from which sand castings are made. Foundries had numerous patterns for most castings and these were usually sequentially numbered. Over time, patterns wore out and were replaced with new patterns but the pattern numbers were not re-used. As far as I know, these numbers are not judged.

Tip, if you're interested: 3846559 manifolds produced as early as 1966 probably had "low" pattern numbers.

[Erv M.]

Re: 1966 Exhaust Manifold #'s

John:

Thank you for the clarification.

Anyone out there with a early 66 that can tell me what pattern number you have on your car?

[Erv M.]

Re: 1966 Exhaust Manifold #'s

John:

Thank you for the clarification.

Anyone out there with a early 66 that can tell me what pattern number you have on your car?

Need some help please.

[Gary B.]

Re: 1966 Exhaust Manifold #'s

Erv,

Your best research reference might be Noland Adams' Restoration book Vol II, which lists a number of exhaust manifold suffixes and other codes for misc items based on owner's surveys. I suggest you obtain a copy of Noland's book. It's a has a lot of valuable information of this sort.

Gary

[David L.]

Re: 1966 Exhaust Manifold #'s

Err,

When I bought my 1966 Corvette (Feb. 1966 build) back in 1979 it did not have the original engine. The exhaust manifolds were are also not original.
"3846559A" ,"LH2" ,"SCC", and "1-28-76"
"3747042", "RH47", and "C22"

However, back in the 1980's I bought various 3846559 and 3747042 exhaust manifolds at swap meets. I also bought a complete unmodified 1966 Chevrolet 327 engine ("T0521HAR", casting date "E186" or maybe it is "E136") from a salvage yard for $25. Most all of the components on the engine were dated in May 1966. The R/S exhaust manifold is cast "3747042" with a casting date "E206". I believe that I MIGHT still have the manifold in my garage. When I get a chance I will check to see what the number is after the "RH" casting. The engine was assembled on May 21, 1966, in Tonowanda and the manifold was cast on May 20, 1966 only one day prior I assume somewhere in or near Tonowanda. I also assume that the exhaust manifold for 327 Corvettes were cast somewhere in or near Flint so this information will probably be useless for you.

Dave

[Joe L.]

Re: 1966 Exhaust Manifold #'s

Err,

When I bought my 1966 Corvette (Feb. 1966 build) back in 1979 it did not have the original engine. The exhaust manifolds were are also not original.
"3846559A" ,"LH2" ,"SCC", and "1-28-76"
"3747042", "RH47", and "C22"

However, back in the 1980's I bought various 3846559 and 3747042 exhaust manifolds at swap meets. I also bought a complete unmodified 1966 Chevrolet 327 engine ("T0521HAR", casting date "E186" or maybe it is "E136") from a salvage yard for $25. Most all of the components on the engine were dated in May 1966. The R/S exhaust manifold is cast "3747042" with a casting date "E206". I believe that I MIGHT still have the manifold in my garage. When I get a chance I will check to see what the number is after the "RH" casting. The engine was assembled on May 21, 1966, in Tonowanda and the manifold was cast on May 20, 1966 only one day prior I assume somewhere in or near Tonowanda. I also assume that the exhaust manifold for 327 Corvettes were cast somewhere in or near Flint so this information will probably be useless for you.

Dave

Dave------

Until 1985, there existed the Tonawanda gray iron foundry and it was adjacent to the Tonawanda engine plant. So, raw castings only had to go "next door" for machining and assembly. This included all cast engine parts except cast crankshafts. The Tonawanda forge was also nearby and there forged crankshafts were manufactured. After 1985 the Tonawanda foundry was shut down and abandoned. Tonawanda-machined castings were then sourced from the GM foundries in Defiance, OH, St. Catherines, Ontario Canada, and Danville, IL. Seems like the "next door" foundry would have been way more efficient but, for whatever reason, it didn't work out that way.

Flint-machined manifolds were cast at Saginaw, about 60 miles north of Flint. However, the logistics were such that it's not uncommon to see engine parts cast the day before the engine was machined and assembled.

[Joe L.]

Re: 1966 Exhaust Manifold #'s

Erv,

Your best research reference might be Noland Adams' Restoration book Vol II, which lists a number of exhaust manifold suffixes and other codes for misc items based on owner's surveys. I suggest you obtain a copy of Noland's book. It's a has a lot of valuable information of this sort.

Gary

Gary-----


Yes, there is some information regarding pattern numbers in the Noland Adam's restoration book in the survey section. He does not have the pattern numbers for all the exhaust manifolds but he has it for a few. For 1966 Corvette small blocks surveyed these range from 20 to 45. Curiously, these are well within the range of what I would expect for 1966 cast small block manifolds.

I certainly hope that this does not become a new "judging criteria", though. I offered information regarding pattern numbers as purely a CURIOSITY. It's in NO WAY a science.