Strange aluminum BB 69 intake question

[Steve Antonucci]

While cruzing eBay, I found a big block aluminum intake with a strange number
that doesn't appear in any of my reference books. I was wondering if any
members could ( or would ) comment on its likely application. The plenum
design is somewhat peculiar. Could this have been a service replacement, or
possibly an "over the counter" intake from Chevy parts? It doesn't seem to
apply to any of the cars/engines I know and I thought it might have been a
Corvette oddity.

GM PART # 3963647 and a cast date of 7-14-69

eBay Item number: 2494893138

Steve

[Clem Z.]

Re: Strange aluminum BB 69 intake question

it could be a marine intake

[Steve Antonucci]

Re: Strange aluminum BB 69 intake question

That's interesting Clem!

I never think of marine engines as having intakes like these. They're just
not in my scope of experience.

Steve

[Clem Z.]

Re: Strange aluminum BB 69 intake question

if a casting # is not listed on any of the auto web sites i would guess it would be marine issue

[Clem Z.]

after looking at the pictures i think

that the carb mounting area may have been modified.

[Joe L.]

Re: Strange aluminum BB 69 intake question

Steve----

This is some sort of early GM over-the-counter performance manifold. Regardless of what the seller says, I really don't think that it was ever factory-installed on a PRODUCTION car, COPO or otherwise. It may have been installed by dealers after the car arrived there and was "performance-modified".

First of all, there are no provisions, at all, for a choke on this manifold. Second, the heater hose fitting bosses are not drilled and tapped. Therefore, any car using this manifold could not have had a heater/defroster. Defrosters were government-mandated on cars built after 1-1-68, so I'm sure that GM wouldn't have built any cars for public sale after that time without them.

[Steve Antonucci]

Re: Strange aluminum BB 69 intake question

Joe,

Good observations! So, wouldn't that indicate that this is some sort of
factory racing manifold? Assuming Chevy actually manufactured such a beast.

What do you make of that carb mounting flange bolt pattern? Is that for both
Holley & Rochester carbs.?

Lastly, do you think this could be for a marine application? Obviously, no
heater ( defroster ) needed there and probably no need for a choke - huh?

Steve

[Clem Z.]

what joe pointed out is why i

posted it was a marine manifold most likely machined by mercury in stllwater they did all their own machine work on the GM engine used in boats. they even ground their own cranks and of course the did the machine work on the ZR-1 engines

[Mark #28455]

Re: what joe pointed out is why i

The dual carb bolt pattern is common on marine intakes. I would bet the primary side of the carb opening was widened at one time or another - all the original marine intakes I have seen were a little narrower at the primary end. I also don't see why GM would have cared about a Q-jet "racing" intake as they always put Holleys on the highest perf engines anyway.