[1968firebird455]

I have the original Quadrajet off my 1978 W72 Trans Am that I have on my 455 transplant motor. When I start the car it fires right off but isn't hitting on all cylinders like its flooded until you clear it out. Wide open throttle is great but it seems a little sluggish under part throttle. Now that Cliff is retired who is the go to guy to have this gone through? Has anyone delt with Philip Cancilla at Custom Built Carbs in NJ?

[Ram Air IV Jack]

Originally Posted by 1968firebird455

I have the original Quadrajet off my 1978 W72 Trans Am that I have on my 455 transplant motor. When I start the car it fires right off but isn't hitting on all cylinders like its flooded until you clear it out. Wide open throttle is great but it seems a little sluggish under part throttle. Now that Cliff is retired who is the go to guy to have this gone through? Has anyone delt with Philip Cancilla at Custom Built Carbs in NJ?

I thought Cliff was still working on carbs? Give him a call or email him to check for sure. Cliff is the best and probably could make a good guess as to the problem you are having.

[25stevem]

Don’t keep driving it even to test it if your seeing signs of the plugs getting wet!
You can wash out the rings and cylinder walls in no time if it’s bad enough!

What Cam is in your motor, or do you know how much hot idle vacuum the motor is pulling?

If your cam has close to or over 225 duration @ .050” then that original primary power piston spring that was used on the 400 motor is too stiff which will make for a rich running primary side.

If I recall right that year carb has a fuel bowl vent or some hole on the top that’s real close to the top of the holder for the power piston hanger.
With the motor off stick something down in there and see if when pushing down you can feel the power piston going up and down also.

If yes then do the same thing with the motor at idle and the motors level of vacuum should be holding the piston once again all the way down.

If not then you have just found where a big part of your poor running condition is stemming from.

Don’t just throw that carb away since it’s a 800 cfm version since it was on a 78 TA.

[77 TRASHCAN]

X2 on not throwing it away! (Sell it to me)

Cliff only sells parts now. Www.cliffshighperformance.com he CAN sell you the very best kit and parts, though. Ask him about someone to furnish the labor to properly re- Kildare your carb!!!

[1968firebird455]

Not throwing it away. Just need it to run right so I can beat on this old 29k mile car how it was intended. I have a roller cam in there. I have to look at the specs but it gets **** vacuum so that's probably a contributor. I have rebuilt a few holleys and twojets but only play around on the outside of a quadrajet. I'd rather send it to someone that knows them.

[Sirrotica]

Originally Posted by 1968firebird455

Not throwing it away. Just need it to run right so I can beat on this old 29k mile car how it was intended. I have a roller cam in there. I have to look at the specs but it gets **** vacuum so that's probably a contributor. I have rebuilt a few holleys and twojets but only play around on the outside of a quadrajet. I'd rather send it to someone that knows them.

Chances are good that the vacuum break diaphragms (choke pull offs) on the passenger side front, and rear, are either non operational, due to a bad diaphragm, or just out of adjustment. These, along with cold choke thermostat spring tension, and fast idle adjustments are what give your engine air when it starts. and keeps it running while the engine warms up, and then transitions to WO choke.

Since these diaphragms are pushing 40 plus years old, they could very well have internal leakage. When all is working as it should the cold start to fully warmed engine is seamless, and runs as well as any FI car does. All it takes is one link in the chain to be off, and it will do just as you have described.

If you read over the shop instructions for a Q Jet it tell you exactly how to make the adjustments, (don't skip over any of the adjustments, and do them in the prescribed order) when done it will run perfectly.

Member here, Shaker455, does mail order carb repairs, you might try PMing him.

[bhill86]

For what it’s worth, depending on Cliffs recommendations, you may decide to try it yourself. I rebuild a spare Holley I had that I used while I tinkered with my Qjet. I didn’t do much but replace the primary and secondary rods, power piston spring, accelerator pump, jets, needle and seat assembly, removed, drilled and replaced the idle tubes and down channel restrictions. I also installed new throttle shaft bushings. Those things would’ve all sounded intimidating to me in the past but it really wasn’t hard to do and I’d do it again without question. Knowing what to do is more than half the battle I feel. There are some good YouTube videos showing disassembly.

[25stevem]

If you have successfully rebuilt a 2 bbl Rochester then there’s no reason you can’t do the same with a Qjet!
Most times the hardest thing is getting the choke tower rod back in its lever in the main body or backing the accelerator lever roll pin back in place.

Even that you can eliminate once you get the air horn off.
I just heat up the lever end of the rod red hot and bend the last 90 degree out of it, then with a hack saw I put in two new notches to take a Jesus clip.
Then you never have to deal with that roll pin again!

[sdbob]

Get Cliffs Qjet book.

[1968firebird455]

I have the book. I was really hoping to just send it out. While I do enjoy fixing things I am very short on time and patience at the moment. Between work, house hunting and a baby on the way the car may just sit all summer.

[shaker455]

Originally Posted by 1968firebird455

I have the book. I was really hoping to just send it out. While I do enjoy fixing things I am very short on time and patience at the moment. Between work, house hunting and a baby on the way the car may just sit all summer.

Hello,
I can rebuild your Qjet, PM sent

[77 TRASHCAN]

Originally Posted by shaker455

Hello,
I can rebuild your Qjet, PM sent

Hadn't seen much of you lately...life can be busy....

[shaker455]

Originally Posted by 77 TRASHCAN

Hadn't seen much of you lately...life can be busy....

Hey how are you?
I'm around but are busy.
How you been?