1980's Truck Quadrajet
04-26-2017, 01:56 PM
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Car: 1985 Trans Am
Engine: 350
Transmission: T5
1980's Truck Quadrajet
The previous owner of my Trans Am removed a lot of parts off the stock Q-Jet, so I bought another to rebuild as a replacement. The number is 17081283, which comes up as a 1981 Truck/Van carburetor.
In Lars' Tuning Papers, he says that 1980's truck carbs should not be used in a performance application. Can anyone back that up? I don't want to go through the trouble of rebuilding it just to have a carb as bad as mine currently is.
In Lars' Tuning Papers, he says that 1980's truck carbs should not be used in a performance application. Can anyone back that up? I don't want to go through the trouble of rebuilding it just to have a carb as bad as mine currently is.
04-28-2017, 06:48 PM
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: 1980's Truck Quadrajet
I fed a 400 HP 350 with a 1983 305 Van Q-Jet. 17083226
It had 72 primary jets, 50m primary rods, DR secondary rods and a F-hanger from the factory. Ended up using 74 jets, 46m primary rods, DR rods and the F-hanger. Ground the tab down so the air door would open 90° and used a high flow needle and seat for a 70s big block application. Was a great carb. You have to resize some of the idle limiting passage ways but it worked great otherwise. Other than that the primary power piston spring is pretty weak to keep the primary sode out of power mode for emissions but that actually works in your favor when you have a nice cam and reduced idle vacuum. The 80s truck carbs also had an APT screw from the factory that was set pretty lean. You can adjust it out a little and richen the cruise mixture a bit. Helps to stay a little richer with a cam that has alot of overlap. Finally the secondarys have a hole right in front of the air door that could stand to be a little larger. It funtions as an accelerator pump for the secondaries. You can grind a transition slot into the chevy aor doors like the 400 and 455 pontiacs had. Really helps the response when the secondaries open by pulling more fuel from that passageway
It had 72 primary jets, 50m primary rods, DR secondary rods and a F-hanger from the factory. Ended up using 74 jets, 46m primary rods, DR rods and the F-hanger. Ground the tab down so the air door would open 90° and used a high flow needle and seat for a 70s big block application. Was a great carb. You have to resize some of the idle limiting passage ways but it worked great otherwise. Other than that the primary power piston spring is pretty weak to keep the primary sode out of power mode for emissions but that actually works in your favor when you have a nice cam and reduced idle vacuum. The 80s truck carbs also had an APT screw from the factory that was set pretty lean. You can adjust it out a little and richen the cruise mixture a bit. Helps to stay a little richer with a cam that has alot of overlap. Finally the secondarys have a hole right in front of the air door that could stand to be a little larger. It funtions as an accelerator pump for the secondaries. You can grind a transition slot into the chevy aor doors like the 400 and 455 pontiacs had. Really helps the response when the secondaries open by pulling more fuel from that passageway
Last edited by Fast355; 04-28-2017 at 06:56 PM.
04-28-2017, 08:00 PM
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: 1980's Truck Quadrajet
I fed a 400 HP 350 with a 1983 305 Van Q-Jet. 17083226
It had 72 primary jets, 50m primary rods, DR secondary rods and a F-hanger from the factory. Ended up using 74 jets, 46m primary rods, DR rods and the F-hanger. Ground the tab down so the air door would open 90° and used a high flow needle and seat for a 70s big block application. Was a great carb. You have to resize some of the idle limiting passage ways but it worked great otherwise. Other than that the primary power piston spring is pretty weak to keep the primary sode out of power mode for emissions but that actually works in your favor when you have a nice cam and reduced idle vacuum. The 80s truck carbs also had an APT screw from the factory that was set pretty lean. You can adjust it out a little and richen the cruise mixture a bit. Helps to stay a little richer with a cam that has alot of overlap. Finally the secondarys have a hole right in front of the air door that could stand to be a little larger. It funtions as an accelerator pump for the secondaries. You can grind a transition slot into the chevy aor doors like the 400 and 455 pontiacs had. Really helps the response when the secondaries open by pulling more fuel from that passageway
It had 72 primary jets, 50m primary rods, DR secondary rods and a F-hanger from the factory. Ended up using 74 jets, 46m primary rods, DR rods and the F-hanger. Ground the tab down so the air door would open 90° and used a high flow needle and seat for a 70s big block application. Was a great carb. You have to resize some of the idle limiting passage ways but it worked great otherwise. Other than that the primary power piston spring is pretty weak to keep the primary sode out of power mode for emissions but that actually works in your favor when you have a nice cam and reduced idle vacuum. The 80s truck carbs also had an APT screw from the factory that was set pretty lean. You can adjust it out a little and richen the cruise mixture a bit. Helps to stay a little richer with a cam that has alot of overlap. Finally the secondarys have a hole right in front of the air door that could stand to be a little larger. It funtions as an accelerator pump for the secondaries. You can grind a transition slot into the chevy aor doors like the 400 and 455 pontiacs had. Really helps the response when the secondaries open by pulling more fuel from that passageway