Quadrajet questions?

[waggin'ear]

I am looking to get a new carb for my '74. I currently have a holley 450CFM spreadbore carb that is supposed to be a q-jet replacement. I don't know squat about my cam. I am looking to increase power and the holley stumbles or stalls pretty hard at angles. The engine is a 1970 SBC350 with a manual tranny.

I am looking to get a 750cfm Q-jet. Any ideas on years compatability. How much should I spend? Anybody have any for sale?

On a somewhat related topic. can you use the holley pro-jection with a spreadbore manifold?

[Cecil14]

Originally posted by waggin'ear:
I am looking to get a new carb for my '74. I currently have a holley 450CFM spreadbore carb that is supposed to be a q-jet replacement. I don't know squat about my cam. I am looking to increase power and the holley stumbles or stalls pretty hard at angles. The engine is a 1970 SBC350 with a manual tranny. First off I don't really see a 450cfm carb being a replacement for a Q-jet but that's holley I guess. Is the holley a squarebore or spreadbore? I would guess square with an adapter?


I am looking to get a 750cfm Q-jet. Any ideas on years compatability. How much should I spend? Anybody have any for sale? Any Q-jet should bolt on, one make (I believe it's oldsmobile but can't remember for sure) has the fuel inlet to the side instead of straight, watch out for that if that's gonna be an issue. They changed a lot of stuff in one year, think it was around '74 or so, can't remember though, and everything before that is the same and everything after that is the same but some parts will not interchange between new and old style. Either one is fine, I prefer the newer style (carb #s start with "70" on the old ones and "170" on the new ones) just be sure of which you get and get parts for that style. Are you looking new or used? For a good core at a junk yard I wouldn't spend anymore than $30-35. If they want more tell them they can keep it, it's a core.


On a somewhat related topic. can you use the holley pro-jection with a spreadbore manifold?Yes you should be able to but you will need a spreadbore to squarebore adapter.

Anthony

[ September 23, 2003, 07:43 PM: Message edited by: Cecil14 ]

[Tad]

Get the Qjet, you will be happy you did.
The side inlet thing (did not know those were specifically an Old's thing) can be a PITA depending on your existing setup.
Been running Qjet's for years and have also tried a few Holley's, and Carters, was not the same on any level.

[waggin'ear]

Thanks,

The current carb I have is a Holley 4360. It is a spreadbore carb and it is 450CFM.. Go figure...

I will start hunting for a Q-jet.

Which Q-jet book is the best? Or does anyone know a good website?

[1BDWAGN]

There is a book by Doug Roe that explains a lot of information about Q-jets including rebuilding and modifying them. They came in two sizes 750 cfm and 795 cfm. The book explains how to tell the difference. Also most Chevy Q-jets have the inlet to the side while the BOP (and Caddy) have the straight inlet. Several people I know prefer the later style Quadrajets that have the adjustable part throttle (APT). Because they are smog carbs they have lean jetting from the factory but after some new rods and jets are installed and some modification to the idle air circuits they perform awesome.