Hand-stamped Big Block Intake

[Jonathan C.]

I have a big block intake and cannot make sense of where it was from. I initially thought it was a '68 390 horse but the #'s don't match up. The #'s are 3937793. The first two (39) are cast but the (37793) are hand stamped. Thanks in advance.

Jonathan

[Joe L.]

Re: Hand-stamped Big Block Intake

Jonathan-----

What you describe is fairly common on these late 60's-early 70's big block aluminum manifolds. For 1968 there were two different L-36 manifolds. The first was GM CASTING #3919849. The second was GM #3937793. These manifold differed in only minor ways. Apparently, the 3919849 could be converted to a 3937793 by a few simple machining operations OR most of the mold components were the same between the 2 manifolds (including the pieces with the casting number on it) and so, initially, the casting number was not changed. Subsequent to casting and/or machining, the last 4 digits of the casting number were ground off and restamped so that the manifold became the 3937793 for ID purposes.

This same procedure was used for other manifolds during this period for similar reasons.

[Jonathan C.]

Thanks Joe *NM*

[Mark #28455]

check date code

Apparently, there was an early and a late intake. Check the date code before you jump to conclusions. There are also more than a few sellers who just ground off and restamped an offending number too. For instance, if your car is a late 1968 model with a now restamped intake, but the intake has an early 1967/68 date code, I would be less likely to accept it as original. If however the date code is close to the production date of the car (within a month or two) it is more plausible that it could be original (unless it's an early car that was built before the later intake was introduced).

Mark