Help! Rochester Quadrajet Choke problem

Reply Subscribe

Thread Tools

Search this Thread

Apr 22, 2007 | 06:56 PM

Mikeg72

Thread Starter

Advanced

Joined: Oct 2006

Posts: 66

Likes: 0

Help! Rochester Quadrajet Choke problem

I have a "72" 454 with a Rochester Quadrajet. The car starts fine when cold and runs great until I shut it off. (vacuume choke). When I try to restart (warm engine), the coke plates close and it refuses to start. I have to take off the air cleaner and hold the choke plates open and it starts right up. (hard to look cool when you have to ask a stranger to hold the choke plates open at the local Ice Cream stand)
If I wire the plates open, (yea you guessed it) it won't start when cold.
Ouch! Kinda takes the fun out of driving that beautiful beast.

Any helpful tips? P.S. I'd love to junk the carb for a new Holley or Edelbrock carb but I'd like to let the credit card cool off until next year and find a fix for the current carb for this year.

Thanks!!

Mike

Apr 22, 2007 | 07:08 PM

wombvette

Le Mans Master

Joined: Jan 2000

Posts: 8,918

Likes: 27

From: New Hill NC

The choke pull off is bad.

Apr 22, 2007 | 07:10 PM

tellcom2001

Instructor

Joined: Mar 2006

Posts: 246

Likes: 1

From: west melbourne florida

i put an edelbrock on mine with a 350 hp motor the edelbrock isnt my first choice for a carb im going to rebuild my q-jet my edelbrock 600 cfm had to change the main squirt,metering rods,springs,and now the accelerator pump,and who knows what next..dosent get enough fuel

Apr 22, 2007 | 08:02 PM

dgruenke

Drifting

Joined: Apr 2002

Posts: 1,716

Likes: 4

From: New Baden Illinois

Have you tried adjusting the choke? I believe there are a few screws that hold the choke onto the carb. You can loosen those and rotate the choke until the plates are in the correct position.

Apr 22, 2007 | 08:55 PM

noonie

Race Director

Joined: Mar 2006

Posts: 14,112

Likes: 28

From: Florida

It shouldn't close if the engine is still warm.
Check the bimetallic adjustment and operation of the pull off.

Apr 23, 2007 | 05:26 AM

aussiejohn

Drifting

Joined: Jul 2002

Posts: 1,944

Likes: 20

From: The only Corvettes in Highett Victoria

Stick with the Q-jet

Mikeg,
General Motors knew what it was doing when they decided to put a Q-jet on your 454. Just follow the advice of noonie and others and a simple repair will fix your problem. Your car is 35 years old!!! So is the carby!!! Some things just wear a little bit and throw the whole "balance" off. Fix the choke and the "balance" of the whole carb will return to where it was before this problem reared its head. Spend a little more and get the whole carb freshened and the car should run like new.

Regards from Down Under

aussiejohn

Apr 23, 2007 | 12:41 PM

427-390

Drifting

Joined: May 2006

Posts: 1,425

Likes: 0

From: Seattle Wash.

Quote:

Originally Posted by aussiejohn

aussiejohn

Excellent advice!

Apr 23, 2007 | 02:02 PM

lars

Tech Contributor

Joined: Aug 1999

Posts: 14,380

Likes: 6,391

From: At my Bar drinking and wrenching in Lafayette Colorado

The 72 Q-Jet uses a choke pulloff with a spring wound around the pulloff arm. This spring causes the choke to close any time the engine is shut off - even if the engine is hot. The intent was that by closing the choke on a hot engine, the engine would re-start without touching the gas pedal, followed by the pulloff retracting and pulling the choke plate open. But I see this not working very well in many applications. To fix it, simply take a pair of snips and cut the spiral-wound spring off of the choke pulloff arm. This will allow the choke to stay open when the engine is hot. It will close normally when the engine is cold. (This all assumes that your choke pulloff is functional... suck on it to check it).