Tunable carb
Thread Starter
Safety Car
Joined: Oct 2005
Posts: 3,570
Likes: 1
From: Algonac Michigan
Tunable carb
I got a Q-Jet carb from a friend and I was wondering if it is considered a tunable carb for street use??? #17057287 Also if someone could tell me what was this carbs original application,it would be greatly appreciated..
Later,
Sly
Later,
Sly
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
There were 94 different secondary metering rods made for the 'Jet. Primary metering rods from 36 to 50 or there abouts. Primary jets from 66 to 78. There were 4 or 5 different float shapes and around 14 or 15 different secondary rod hangers. This, together with 3 or 4 different auxiliary fuel enrichment schemes, 2 different sizes (750 and 800 CFM) and the fact that the carburetor is basically infinitely adjustable, the answer to your question is, no, the Quadrajet is not very tunable so you may as well send it to me. I'll pay shipping.
The Quadrajet is the most tunable carburetor EVER installed on any mass produced automobile. I would say up wards of 25 to 30 million have been made.
BigBlockk
Later.....
The Quadrajet is the most tunable carburetor EVER installed on any mass produced automobile. I would say up wards of 25 to 30 million have been made.
BigBlockk
Later.....
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
There are 2 schools of thought here on the boards. There are those that replace the 'Jet with a Holley and those that learn to tune the 'Jet. The Holley is simply an expensive way to pour gasoline into an engine while the Quadrajet actually meters fuel properly. Yes, I think you should tune the 'Jet.
BigBlockk
Later.....
BigBlockk
Later.....
Racer
Joined: Jun 2004
Posts: 384
Likes: 0
From: freehold NJ
I'm a quadrajet newbie. I just successfully removed and re-installed my distributor and the car fired right up! Now I plan on curving it. But first I want to change the idle speed. Soooo, (Bigblock) where is the idle speed adjustment screw on a 74 L48 Q-jet?
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Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
Originally Posted by BigBlockk
There are 2 schools of thought here on the boards. There are those that replace the 'Jet with a Holley and those that learn to tune the 'Jet. The Holley is simply an expensive way to pour gasoline into an engine while the Quadrajet actually meters fuel properly. Yes, I think you should tune the 'Jet.
BigBlockk
Later.....
BigBlockk
Later.....
Hardest part of tuning later model q-jets is finding those damn primary metering rods. I'm running 47K rods with 75 jets and it runs reeeeal nice. I left the secondaries the way edelbrock sent them as.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
Originally Posted by Kalway
Hardest part of tuning later model q-jets is finding those damn primary metering rods. I'm running 47K rods with 75 jets and it runs reeeeal nice. I left the secondaries the way edelbrock sent them as.BigBlockk
Later.....
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by BigBlockk
Good point. Not all of these are still available. I know Lars has had to make his own metering rods.
BigBlockk
Later.....
BigBlockk
Later.....
Yup, he turned my 48M to the 48K spec. I just switched those out for some original 47K rods this weekend and the throttle response at cruising speeds seems to be a little gruntier. Of course I'm sure the adjusted timing curve and better fuel helped with that, too.
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by sly vette
Well I guess I get to go to Jet school
