67 cat conv

E

ED FARRELL

New member
Joined
May 22, 2015
Messages
20
Reaction score
0
Points
0
i HAVE PRETTY MUCH DECIDED TO UPGRADE FROM A 2 BBL CARB TO A SMALL 4 BBL DURING MY REBUILD. THIS BRINGS UP SOME QUESTIONS.

WILL A STOCK 4 BBL MANIFOLD FIT ON A STOCK 67 400ci MOTOR THE MOTOR PRESENTLY IS A 2BBL 265 HP. IF SO, HAS ANYONE GOT ONE AVAILABLE? I REALLY WANT TO STAY WITH A PONTIAC MANIFOLD IF AT ALL POSSIBLE.

DURING THE REBUILD THE HEADS AND BLOCK WILL BE MILLED SLIGHTLY AND A SLIGHTLY HOTTER CAM WILL BE INSTALLED. I EXPECT THE CYLINDERS WILL BE BORED .30. WITH THIS IN MIND, WHAT SIZE CARB SHOULD I PUT IN. IT WAS SUGGESTED THAT A 650 HOLLY WOULD WORK. I DON'T WANT A DRAGSTER HERE, JUST A LITTLE STRONGER MOTOR.

ONE MORE THING. IS IT WISE TO REPLACE THE RODS WITH THE PISTONS?

THANKS IN ADVANCE FOR ANY ADVICE

ED
 
the factory 4bbl manifold is a spreadbore configuration so any carburetor you decide on would have to be also a spreadbore. Look at what Holley has in the 4175 series, they have 650's, not sure if they have a Pontiac model otherwise you could adapt a Chevy model. Have the rods magnafluxed to determine what condition they are in.
 
TY Doug! They say that they are for a quadrajet. My book says that the lower HP 400 motor came with a plain 4 BBL and only the higher HP ones came with a quadrajet. My question is, can I use an after market carb on this manifold in place of a quad. I think I know the answer but I need to hear it.

Thanks
 
Yes with an adapter, but for vintage look, a QJet will do also.

Most Qjets came in the common 750 CFM with some bigger motors ( 455 -500) used the 800 CFM model.

Doug in P.R:cool:
______________________________
 
Either your book is wrong or confusing. The only 4bbl Pontiac used from 1967 and up was the Quadrajet.
 
No argument. I am going with you guys but my 67 service manual engine chart doesn't show quadrajets until the 360 hp motor. Mine is the 265hp 8.6 comp ratio. Prior to 360 hp it just shows generic 4bbl.
Do you recommend a rebuilt quadrajet 750 or a new holly spreadbore? And if a Holly, how large? 650/750??

ED
 
So what 4bbl does your manual show for less than the 360hp? Unfortunately there are lots of crappy commercially rebuilt quadrajets. If you can get a good Quad go for it otherwise the 650 Holley spreadbore with vacuum secondaries.
 
The book just lists 2 bbl, 4 bbl, quadrajet. No brandname for the 4bbl.
Summit racing has a Jet performance quadrajet #36002. Stage 2 carb for pontiacs. Have you heard anything about them?
______________________________
 
even though the 35001 is for a chevy as opposed to the 32101 or 32102 which are for a Pontiac? The 32101 is a stage 1 and the 102 is a stage 2.
 
I've seen 429 '67 Cadillacs still using the Rochester 4GC , Not sure what the '67 Pontiac 428 used though...........

Just read some Pontiac 400's came with 800 CFM QJets from the factory

A 800 CFM QJet can support up to 750 HP according to QJet expert Cliff Ruggles.

Edlebrock makes both versions.

It it was my car, Its going to have a Qjet ;) ( my grandmother worked at the Rochester , NY plant )

Doug in P.R.:cool:
______________________________
 
LMAO! Did she really make qjets? LOL.

Anyway, thanks for your reply. Summit claims that the 32102, a second stage rochester 800cfm for Pontiacs from 350cubes and up, is the way to go. My only concern is that it may be too many cfm's for the "slightly" modified 400cube motor. Everything I have read so far says that it will work but I am just trying to be certain.

Both you and melsg5 have been a tremendous help and I thank you both for that.

Unless one of you disagree, I think I am going with a stock manifold and the 32102 qjet.

Ed
 
that's weird I used the filter on Summits web site and all they showed were Chevy carburetors. I agree go with the 32101 or 32102 if you see more changes eventually. The secondary air valve has an adjustable spring to compensate for too much air flow.
 
Summit's site had me turned around several times also. All's well that ends well. Thanks for your patience and the info. Really appreciate it.

Ed
 
Just a note , Qjets are "on demand "type of carb, which means that the engine will only use what it needs , no such thing as "overcarbing" with a Qjet.

( not sure what she did there :rolleyes:, and my grandfather worked down the street at the old Rochester Delco " electrical" plant at the same time.)

My other grandfather was a salesman at Valley Cadillac in Downtown Rochester also.

His fellow salesman was this guy.....https://en.wikipedia.org/wiki/Irving_Crane

Doug in P.R.:cool:
 
You must log in or register to reply here.

Share this page

Back
Top