BruceP7

Hi Guys, Trying to finish a 1958 283/270 dual quad set-up and have a question on what two (2) intake manifold holes are used for. Photo's below show the two holes just under the black ground wire.

Both holes are threaded and I'm not sure what goes into them (if anything). Forward threaded hole goes completely through the manifold and the rear hole (facing the car) does not go all the way through the manifold. Are these used in a dual quad set-up? Are they for vacuum advance or pressure gauge?

thanks for any advice you can offer, Bruce

Frankie the Fink

The answer is -- wait for it....

NOTHING.... My original 270 hp car had two Allen head bolts in those holes the entire time I owned it....I don't know if they were added by a prior owner or not..

At one point an old-timer told me it was for the Powerglide kickdown linkage - which is rare, and I mean REALLY rare, on a dual quad car...

MikeM

Dual four barrel carbs were very common on 1956 PG Corvettes. Maybe '57 as well. Don't know.

Frankie the Fink

Mebbe - I've yet to see one; although someone did ask me to find the linkage for one years ago (nobody had it)...
But, to the OP's point, that's what someone posited the holes were for, I'm not 100% certain...

MikeM

That might possibly have been a coil mounting location for pass car. Just another guess.

DZAUTO

Those 2 holes are for cars that have a Powerglide transmission. A bracket is installed there for the linkage that goes from the throttle linkage to the PG tranny.
There HAS TO BE SOMEONE HERE who can paste a picture.

Frankie the Fink

Ha! I'm waiting...

<sound of crickets>

MikeM

Frankie the Fink

Nice!

And the dual quad linkage on that first one is set up "shotgun", not what I like; especially not with a "slide and glide" auto..

C.T.

As Bruce indicated, the forward hole is open to the valley and will allow an oily mist to enter the engine compartment. Needs to be plugged.

DZAUTO

That is exactly correct. Just a short 5/16 coarse thread bolt with some sealant on the threads will do the trick.