Rejetting a quadrajet. Stock Qj on a 454.

[lyrikz]

I have a mildly built 454 with a good size cam. The heads are not the smallest factory and not the big ported ones. The medium port heads. Flat tappet cam.

The quadrajet on it is a 81 rochester that was rebuilt and is perfectly stock. Im sure i have to rejet this thing. Any thoughts or suggestions....

[geezer#99]

You could rejet maybe. How does it run. Does it surge at cruise? One cheap way to see if you need richer jets is to make a makeshift limiter that keeps your choke plate partly closed. It'll run richer. Manual choke carbs are easy to do that with buy I assume you have an electric choke.
Another way to richen it is to adjust the adjustable part throttle (apt) on the primary rods. THe power piston the rods attach to has a short tab on it that controls the depth the rods go into the jets. The apt is a special screw that uses a specially shaped tool to turn it. Screw it in makes your primaries leaner. Out makes it richer. Apt is generally 3 turns from bottom.
Here's a link for quad info. There should be apt info there.

http://www.digitalcorvettes.com/foru...ad.php?t=88376

[lyrikz]

Originally Posted by geezer#99

You could rejet maybe. How does it run. Does it surge at cruise? One cheap way to see if you need richer jets is to make a makeshift limiter that keeps your choke plate partly closed. It'll run richer. Manual choke carbs are easy to do that with buy I assume you have an electric choke.
Another way to richen it is to adjust the adjustable part throttle (apt) on the primary rods. THe power piston the rods attach to has a short tab on it that controls the depth the rods go into the jets. The apt is a special screw that uses a specially shaped tool to turn it. Screw it in makes your primaries leaner. Out makes it richer. Apt is generally 3 turns from bottom.
Here's a link for quad info. There should be apt info there.

http://www.digitalcorvettes.com/foru...ad.php?t=88376

No, it does not appear to surge at cruise.. Drives pretty good.

[geezer#99]

Drive it and enjoy it. If you've never worked on a quad they can be intimidating though.
Easy to screw up a good running carb.
Don't fix it if it ain't broke.

[lyrikz]

Originally Posted by geezer#99

Drive it and enjoy it. If you've never worked on a quad they can be intimidating though.
Easy to screw up a good running carb.
Don't fix it if it ain't broke.

Just wondering if its getting enough fuel.
Im debating buy 2 true af sensors and installing them in the truck with an af guage. That way i can really see where i am at. Everything else just appears you would be partially guessing.

[geezer#99]

Excellent idea. Always gather info before jumping in and tearing stuff apart.
Ya' know I'm not far away. We could meet up and have a carb day. Ever been up to the wilds of Canada!! I get over to Langley once in awhile. Not far from you.

[lyrikz]

Originally Posted by geezer#99

Excellent idea. Always gather info before jumping in and tearing stuff apart.
Ya' know I'm not far away. We could meet up and have a carb day. Ever been up to the wilds of Canada!! I get over to Langley once in awhile. Not far from you.

My wife is canadian, so ya, i go there a bit. ahaha. Love it over there.

Im going to price out some cheap a/f sensors. See what i can come up with.