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Author Topic:   Qudrajet Carberators
Gordon3E
Dirt Full Roller

Total posts: 67
posted January 24, 2003 10:35 AM
Just bought 4 Qudrajet Carberators. Got the numbers off of them and found rebuild kits for them. But i can't find out how many CFM's they are. Is there a web page that carries these Numbers. Also for Jammin,,, there is a web page that lists "All Block" numbers along with "All head numbers" the web page is 'Mortec.com. they say you can post that site to "OUR's" Just thought i'd let ya know.

KPLugnut
Dirt Freak

Total posts: 408
posted January 24, 2003 08:41 PM
Shoot me the numbers and I can decipher them for you.
Basically, the only quads that were made were either 750cfm or 800cfm. The only ones that were 800cfm were ones that had the fuel inlet coming out straight forward and not to the side. But not ALL quads with inlets like that are 800cfm rated.
FWIW, a well built 750cfm more commmonly found quadrajet is plenty of carb for almost any class that would allow quadrajets.
The trick is in the tuning and internal work.
If you'd like to attempt building them yourself, start by getting a copy of Doug Roe's book titled "Rochester Carburetors". It's available on Amazon.com. Usefull starter info for beginners.

Hope that helps,

Dayton Umholtz, owner
Kinetic Performance

p.s. - on the links page of my website there is a link to a page that tells what the Rochester # scheme means.
here: www.kineticperformance.net

[This message has been edited by KPLugnut (edited January 24, 2003).]

o5racer
Dirt Maniac

Total posts: 115
posted January 25, 2003 11:00 PM
KP you are 99% right. I had a quad off of a 79 vette a few ears back and it had the side inlet with the big throttle bores. I had to compare it to three other carbs to be sure i was looking at it right. But that was the ONLY side inlet big bore that I have seen.

Gordon3E
Dirt Full Roller

Total posts: 67
posted January 27, 2003 07:23 AM
quote:
Originally posted by KPLugnut:
Shoot me the numbers and I can decipher them for you.
Basically, the only quads that were made were either 750cfm or 800cfm. The only ones that were 800cfm were ones that had the fuel inlet coming out straight forward and not to the side. But not ALL quads with inlets like that are 800cfm rated.
FWIW, a well built 750cfm more commmonly found quadrajet is plenty of carb for almost any class that would allow quadrajets.
The trick is in the tuning and internal work.
If you'd like to attempt building them yourself, start by getting a copy of Doug Roe's book titled "Rochester Carburetors". It's available on Amazon.com. Usefull starter info for beginners.

Hope that helps,

Dayton Umholtz, owner
Kinetic Performance

p.s. - on the links page of my website there is a link to a page that tells what the Rochester # scheme means.
here: www.kineticperformance.net

[This message has been edited by KPLugnut (edited January 24, 2003).]


KPLugnut; Thanks for your advice... The Numbers for those 4 Quadrajet Carberators are. There is a top # and a bottom #.
1.) Top# 7044207FB Bottom # 1624
2.) """" 17058213 """"" 3127BJB
3.) """" 7043202FS """"" 0733
4.)"""" 17082253 """"0672DTK
KPLugnut number 4 is a Computor Controlled Carberator. Also don't know what any of these came off of.

DEEDDUDE
Dirt Maniac

Total posts: 111
posted January 27, 2003 04:13 PM
guys, From what I understand, When you look down the primary throttle bores; the 800 cfm has a little bump and the 750 cfm doesn't. I could be wrong... I just found it in Roes book, Yes the 800 cfm does have the bump. I have one of the 800's that came off a chevy what? but, it has the side fuel inlet. Good Luck, Hope it works for you.

[This message has been edited by DEEDDUDE (edited January 27, 2003).]

KPLugnut
Dirt Freak

Total posts: 408
posted January 27, 2003 09:40 PM
Yes, guys, I stand corrected. There WERE a few 800cfm quads that had the side inlet fuel fitting. Corvettes were a prime candidate.
The large Caddy motors had front-facing inlets on their quads and many of them were the large cfm ones.
The main point is, for oval track racing one does NOT need the 800cfm carb to be able to come up with a great racing quadrajet.
The above posts are right, too, in that the primary venturi are shaped differently on the 800cfm ones. The 750cfm ones have a "ring" of sorts around the narrowest part of the venturi area, while the 800cfm carbs do not have that, they only have a "bump" in one spot and not all the way around the circumference of the venturi.
To the best of my knowledge, the secondary size is the same on both carbs. That's mainly why I feel that the 750cfm carb is plenty of carb for any class that allows the quadrajet.
As for the carb numbers supplied above, here's what they are:
#1: 1974 model, standard tranny
#2: 1978 model, standard tranny
#3: 1973 model, automatic trans.
#4: 1982 model, standard trans. computer controlled off a 305 car, probably a Camaro or Firebird. (I have several of these in stock). This one is useless for oval track racing.

Hope that helps,
KPLugnut

Gordon3E
Dirt Full Roller

Total posts: 67
posted January 28, 2003 03:56 AM
Thanks KPLugnut, all of those carbs are 750 cfm's. So i take it that Rodechester carberator company does not excist any more.?

KPLugnut
Dirt Freak

Total posts: 408
posted January 29, 2003 07:07 PM
Rochester Engineering stopped operations some years ago. The carbs everyone hunts for to make into racing carbs (whether 2bbl or quadrajet) haven't been made since the late '70's/early '80's.
However, there are aftermarket sources for ALL parts except for the castings of the bodies, baseplates and tops. Those are no longer made. There are still many floating around out there, tho, and carb rebuilding houses still recondition them and sell them as "factory reconditioned" pieces with healthy over the counter pricetags at parts stores.

We stock all Rochester pieces, and also have some carbs in stock as well.

We do the same for Holley, too.

And not that anyone ever wants them, but we also have access to Carter parts. (pausing to gag)....LOL.


Hope that helps,
KPLugnut

flywheel
Dirt Roller

Total posts: 9
posted January 30, 2003 12:49 PM
how can you distinguish between a 750 and 800 cfm, is it primarys or secondarys that makes the difference.

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