I need adult supervision with regard to the correct casting marks for a 63 340hp exhaust manifold. I have a RH "902" with 8 nubs that measure about 1/8" x 1/2" along the top seam line. My LH "901" has only 4 nubs about 1/8" x 1" along the same seam line. I've seen many examples of the "8 nub" configuration, but none of the "4 nub". Will the one with "4 nubs" receive a deduction or did GM just get manifolds from different foundries? (Both have the correct casting number font and no date)
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Re: C2 exhaust manifold casting marks
I figured the nubs were reminents of the casting process. I was just curious if anyone else knew if this was common on original 63 manifolds or if the left hand manifold was a GM restoration part. I emailed Paragon and they didn't seem to understand my question on the number of castings nubs so I asked if they could email a picture of the top of their manifolds. I haven't recieved a responce. If anyone else could provide more information I'd appreciate it.Comment
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Re: C2 exhaust manifold casting marks
I have the original manifolds on my '63 L-76, and both mine have eight of the features you refer to - four along the top of the log between the center ports and the end, but the one furthest forward end of the LH manifold is very faint.
According to the JG original, manifolds should have a minimum of "seven rectangular projections..." and goes on to say that grinding marks are typical of current service replacement parts, so it sounds like you could get a deduct if you don't have at least seven of these features showing along with a clear as cast parting line.
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