Quadra-Jets, all the same?

Reply Subscribe

Thread Tools

Search this Thread

Oct 13, 2003 | 03:56 PM

467-Ratman

Thread Starter

Burning Brakes

Joined: Aug 2001

Posts: 1,002

Likes: 0

From: Bay City MI.

Quadra-Jets, all the same?

I am looking for a Quadra-Jet for my motor, question are they all the same or is there one that would be better for my big block? Also was told that a marine Q-jet was good too for performance, but does not have a choke.

Oct 13, 2003 | 04:03 PM

Gordonm

Race Director

Joined: Dec 1999

Posts: 19,610

Likes: 778

From: Forked River NJ

Re: Quadra-Jets, all the same? (467-Ratman)

No they are not the same at all. Different size jets, oumps and there was even different cfm. Normal is 750 cfm and I think it was 800 or 830 was the bigger one. Check with Lars on this. Qjet guru.

Oct 13, 2003 | 04:07 PM

Fevre

Race Director

Joined: Mar 2001

Posts: 11,322

Likes: 1

From: Living in the Hartland

Re: Quadra-Jets, all the same? (467-Ratman)

Wish you where closer to me, I'd let you try out my 750 dp to see if you like it any better.

Oct 13, 2003 | 04:27 PM

Larry B.

Le Mans Master

Joined: Sep 2000

Posts: 5,635

Likes: 4

From: Orlando Floriduh

Re: Quadra-Jets, all the same? (467-Ratman)

There are literally hundreds of different Q-jets. Many have the fuel inlets in the front. Some have chokes on the carbs while others use a divorced choke. Over the counter Q-jets are absolute junk and may never work. You can get a new Q-jet from edelbrock. Pick one from ther list. Then get Lars Q-jet tunning paper from http://www.corvettefaq.com and set it up for you application. It is worth the effort.

Oct 13, 2003 | 05:26 PM

467-Ratman

Thread Starter

Burning Brakes

Joined: Aug 2001

Posts: 1,002

Likes: 0

From: Bay City MI.

Re: Quadra-Jets, all the same? (Fevre)

Fevre, Appreciate the thought, I may end up with a 750DP, I have been talking to a lot of guys lately about the Q-jet and when tuned right it sounds like a great carb. The place I bought my 850 from said they would let me trade it back on any other carb so thats most likely what is going to happen. It will make a good winter project to change it!

Oct 13, 2003 | 09:01 PM

74ZZ430

Instructor

Joined: Aug 2000

Posts: 177

Likes: 0

From: Toledo,Ohio,USA

Re: Quadra-Jets, all the same? (467-Ratman)

I've been doing a lot of research on quadrajet recently,since I'm still using one on a ZZ430 clone and very happy with it. From what I can tell most q-jets were 750 cfm except the ones used on big block Buicks, Pontiacs and Oldsmobiles beginning in about 1971 which were 800 cfm, larger primarys. The problem with these units they are all center fuel inlets, although I have seen adapters to make them side inlet, and you would have to modify your linkage for a chevy.
You also want to get a 1974 earlier Q-jet , since 75 and later are harder to modify for performance. Most Q-jet shipped on small blocks the secondary air valve is limited to 70% opening and the big blocks open to 80 to 85% , although this can be easily modified by grinding the factory stop. Lars has been extremely helpful with answering some questions I had.

Oct 14, 2003 | 09:22 PM

LT1driver

Le Mans Master

Joined: Oct 2000

Posts: 6,209

Likes: 33

From: Texas-out west

Re: Quadra-Jets, all the same? (74ZZ430)

The cfm was determined by how much the rear secondary was allowed to open, higher cfm used full opening and lower cfm had linkage set so secondary was restricted. :cheers:

Oct 16, 2003 | 07:52 PM

Kevin Mason

Burning Brakes

Joined: Nov 2000

Posts: 1,123

Likes: 145

Re: Quadra-Jets, all the same? (LT1driver)

Stupit questions, but:

Can a quadrajet designed for an auto be made to work on a car with a manual?

Which quadrajets will work with '69 small block fuel inlet, linkage, etc.?

[Modified by Kevin Mason, 6:55 PM 10/16/2003]