Quad jet replacement

Have a 305 in my model t, has a quad jet, think it may need a rebuild or replacement suggestions?

 

A Holley 600 cfm w/vac secondaries dressed up to look like a 750.... I did one up and included a secondary metering block....
Runs like a champ after a "little" fine tuning...

 

Thanks for the info!

 

I have someone local that does a nice job on the Q-Jets, they're really a nice carb if they work right. I also have a spreadbore Holley that I like quite a bit.

Bob

 

What's your thoughts on tell tale signs it needs replace/rebuild, runnin rich, hard start, stalling.

 

I concur

 

The q-jet really is a good carb for your 305. The small primaries match the lower speed aspects of the 305 well, and you have the large secondaries when you want full power. I would just rebuild it, unless it is one of the later 70's feedback carbs. Feedback style have an electrical connector, avoid them. Use the number stamped on the body to get the right kit. It can be a bit overwhelming, just pay attention to how it all goes together and comes apart. Or send it out to a q-jet specialist and you will be happy with the result.

 

Here's a lenghty read on troubleshooting your carb.
http://www.digitalcorvettes.com/forums/showthread.php?t=88376
Here's a source for rebuilt ones and kits.
http://www.carburetion.com/CarbID/RochesterID.htm
Or here.
http://quadrajetparts.com/

 

There's a great Q jet rebuild video on youtube.

 

Appreciated gentlemen.

 

I had this guy in Phoenix rebuild my Q4. He did an outstanding job. Here is his contact info:
bruce benner: [email protected]

 

Take the old carb to Auto Zone for core. Get new carb. 130$ish?? I've done it more than once. You may have to set the idle. Done! Best carb on the planet. Period!!!


Posted from the TJJ App for iPhone & iPad

 

Forgot to add. They will give you a fresh rebuilt Q-Jet carb in return. A buddy of mine just bought a junk one for 5$ for the core.


Posted from the TJJ App for iPhone & iPad

 

Try adjusting your idle mixture screws first.

 

Q jets have pressed in plugs in the bottom of the jetwell, and they are prone to "seepage". Rochester's "fix" was to put a a piece of absorbant material in the base cavity , directly under the jetwells. Theory was, that manifold vacuul would draw off the fuel. The "seepage" would become "leakage",..and the engine ran rich.

One fix was to remove the carb base, clean the area thoroughly, and coat with epoxy. Another was to tap out the plugs, thread the holes, and screw threaded plugs in, using LocTite. Or, buy a replacement Holley spreadbore.

4TTRUK

 

Learn your Q-jet. You won't beat the mileage and once it's fixed and tuned in correclty, you'll go years.

And I feel like quoting Smokey Yunick but I'll spare you.

 

Timing chain changed, gasket new valves new. But no matter what I try the carb is done..may try the suggest Holley 600 cfm w/vac secondaries

 

the throttle shaft bores are probably worn out. large air leak if they are.

 

Local guy got one from cliffs Q jet. Has it on 400 Ponitac. Works very well.