Quadrajet build thread

[Olds 307 and 403]

I plan on building this 800 cfm model that came off a 85 Buick station wagon with a blown up 307 swirl port motor, had it for 23 years to replace the current super lean current 83 carb on the 70S. I plan on totally recalibrating it for a 220ish duration cam. I need to figure out the air bleeds for this carb for primary metering rods, going to get them from Cliff's High Performance. His big kit will have fasteners, the Metric mixture screws that adjust with a standard screwdriver, the removable plug for the APT, I am notching mine like my 78 carb which allows a part throttle mixture change in seconds. I also plan to buy two fast choke pull offs, one for my 78 carb, try and eliminate the bog, thinking that a faster pull off will help. Also extra Metric mixture screws for the 83 carb. Along with a new copy of the book, about $250 US. I had moved the container outside my shop and the main body was full of water for a month but should be OK, I think. I am also planning on rebushing the primary throttle shaft with Cliff's kit, has a self guiding bit, bushing installer and instructions. I am not sure about the suggested sheet of teflon. There will always be the joining gap, so that makes it less appealing. Amazon does have 1/8" thick sheets, just not sure if I should try it. I will contact Cliff and see if he has an extra power piston metering rod hanger to go with parts I am buying.

 

[Olds 307 and 403]

This carb is like my 83 carb, a weird Canadian market decode. It shows it should be a 1980 federal emissions Pontiac carb but starts with a 1708 number which should be a 82 and up model.

 

[Olds 307 and 403]

I just remembered, I will have a Power Piston in my 260 Dualjet carb. It fixed my 78's choke linkage problem, now it will provide a Power Piston for this carb. See a Dualjet is good for something, Qjet parts😁.

 

[Olds 307 and 403]

So I got all the little pieces from the Dualjet including 51B rods and 72 primary jets. Of course this Dualjet had an oddball long rod on the end of power piston that contacts a treadle valve in the base plate. I think it will be cut off wheel time, other a normal power piston. I sprayed the passages with Motomaster carb cleaner and Kleenflo Combustion Chamber cleaner which really dissolves carbon. I soaked NGK XR5 spark plugs that were gunked up with that combo. A quick blast with crushed glass made them look new. I knocked out the aluminum in the air horn and there some play in the primary shafts.

 

[Rocketman269V]

...........I also plan to buy two fast choke pull offs, one for my 78 carb, try and eliminate the bog, thinking that a faster pull off will help. ............

Generally, if you have a "bog", it's due to the secondary air valve opening too soon. Try tightening the secondary air valve spring in 1/8 turn increments, clockwise, and see if that helps. We used that as a tuning tool on our Q-jet on the Stocker.

 

[Olds 307 and 403]

I did tighten it as much as it should be, has noticeable, light tension. Anymore and the secondaries are delayed. It has CV rods and a G hanger. The 88 only has a factory 1900 flash stall but has 3.42 gears.

 

[Olds 307 and 403]

One of the G body site guys claims he has this carb on his 80 301. It idled fine on my 8 to 1 403 with a 204/214 cam.

 

[Rocketman269V]

............ has noticeable, light tension. Anymore and the secondaries are delayed.......

That's exactly what you want. Believe me; we used the secondary air valve spring as a tuning tool. We were at a test session at Gainesville Raceway, on a cool November day, and when I left the starting line I could feel when the secondaries opened. I backed the air valve spring tension off 1/8 of a turn and the car picked up .20 in the quarter. We normally ran the spring fairly tight down here, due to the warm weather. It won't cost you anything to tighten it up just a little and try it.

 

[Olds 307 and 403]

I did and tightened it slightly. I have it about the perfect amount right now. It only bogs sometimes. The current choke pull off is slower than Cliff recommends, worth a shot. The 88 is fun to drive, just need to get the paint and shifter sorted out.

 

[Olds 307 and 403]

Talked to Cliff this morning. The only part he might not have is a used Power piston, he has sold a lot as of late. He told me to cut the rod off mine Dualjet Power Piston, you can't pull it out. He said double check that pin height is the same as a Qjet. He even has extra linkage, the extra linkage I had is on the carb on my 88. He said to toss the rear pull off. They allow unfiltered air in the motor after the 40 year old filters disintegrate. He is going to drill out the idle tubes to .038", I still need open at the mixture screws and idle channel restrictions and is sending his .044" primary rods and suggested 73 jets to start, which I should have. Also he figured his DA secondary rods would also be close. He also is sending his pump rod with the clip and two sets of the metric idle mixture screws. He says they stick past the base so they are easily adjusted with a standard screw driver. He says this is a great starting point for a carb and figures the cam should be in the 230 duration range. I am also going to try and purchase the small chamber Procomp heads Cutlassefi is doing for 350 dyno motor. I am also willing to buy a set of Sanderson shorties and 2.5" and 3" down pipes with an O2 bung to dyno test against each other. I don't think anyone has ever dynoed them.