Quadrajet Problems
Thread Starter
Racer
Joined: Oct 2006
Posts: 396
Likes: 3
From: Buffalo New York
Quadrajet Problems
I rebuilt the q-jet on my '76 last year. It runs much better, but still has a few issues:
1. The choke seems to function ok, goes from fast idle to slow, and the kickdown works. But I can't start it and go on a cold engine, as soon as I put it in gear and go, it dies. If I let it warm up for 5 minutes, it's ok.
2. When I shut off the engine, I get a few wisps of smoke out the top of the carb.
3. If the car sits for 15 minutes or so warm, it's hard to start. It starts quicker when it's cold!
It looks like I'm in for another rebuild. Now that I've done it once, I feel confident about doing it better this time. I did not replace the float, jets, or seal the well plugs last time. What should I look for?
1. The choke seems to function ok, goes from fast idle to slow, and the kickdown works. But I can't start it and go on a cold engine, as soon as I put it in gear and go, it dies. If I let it warm up for 5 minutes, it's ok.
2. When I shut off the engine, I get a few wisps of smoke out the top of the carb.
3. If the car sits for 15 minutes or so warm, it's hard to start. It starts quicker when it's cold!
It looks like I'm in for another rebuild. Now that I've done it once, I feel confident about doing it better this time. I did not replace the float, jets, or seal the well plugs last time. What should I look for?
Burning Brakes
Joined: Sep 2009
Posts: 1,124
Likes: 140
From: Western New York
Hey Billsfan,
Sounds like your choke needs some fine tuning. Check, also, to make sure your choke pulloff is working. You shouldn't be out in this cold weather on those salty roads, anyway, at least until sometime in April. Sit back, today, and enjoy the Daytona 500 and wish for warmer weather. Good luck, dude. Go Bills!
Sounds like your choke needs some fine tuning. Check, also, to make sure your choke pulloff is working. You shouldn't be out in this cold weather on those salty roads, anyway, at least until sometime in April. Sit back, today, and enjoy the Daytona 500 and wish for warmer weather. Good luck, dude. Go Bills!
Thread Starter
Racer
Joined: Oct 2006
Posts: 396
Likes: 3
From: Buffalo New York
Thanks, guys. It's Monday morning and the Daytona race just finished! I put in a new choke pulloff, and adjusted it with my vacuum gauge according to the manual. I'll try to fine tune it. I still am looking for an answer to the smoke out of the carb. I read somewhere that it indicates that something is leaking, but I can't find that reference. By the way Duane, all those wimps in Philly and Washington will have to hibernate until the snow melts. In Buffalo, a storm like that means we might be a little late for work!!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
How can you see 'smoke' out the carb with the air cleaner on it? Oh...the air cleaner was off! Well, that's your problem....leave the air cleaner on it. Your 'hard start' problems with a warmed up car are likely due to your starting procedure. With a warm engine, I will just hit the key to see if it starts; most of the time it does. When it does not (on infrequent occasion), I'll depress the accel pedal ONE time and it always starts. For cold starts, depress pedal fully one time to set the choke, then crank.
If your carb is built properly and you set it up according to the procedures in the Chevrolet Chassis Service Manual, it will work as intended.
If your carb is built properly and you set it up according to the procedures in the Chevrolet Chassis Service Manual, it will work as intended.
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Instructor
Joined: Dec 2009
Posts: 107
Likes: 0
Q-jet probs.
Most likely the smoke you see rising from the carb is actually fuel vapor
created from a hot engine. Your fuel level in the Q-jet maybe too high and with a hot engine the carb becomes heat soaked which expands the fuel inside the carb causing it to overflow into the primary tubes and down into the hot intake manifold. The puddle of fuel on the inside of the hot manifold turns into vapor and also cause a flooding condition making it hard to start.
created from a hot engine. Your fuel level in the Q-jet maybe too high and with a hot engine the carb becomes heat soaked which expands the fuel inside the carb causing it to overflow into the primary tubes and down into the hot intake manifold. The puddle of fuel on the inside of the hot manifold turns into vapor and also cause a flooding condition making it hard to start.
Thread Starter
Racer
Joined: Oct 2006
Posts: 396
Likes: 3
From: Buffalo New York
Most likely the smoke you see rising from the carb is actually fuel vapor
created from a hot engine. Your fuel level in the Q-jet maybe too high and with a hot engine the carb becomes heat soaked which expands the fuel inside the carb causing it to overflow into the primary tubes and down into the hot intake manifold. The puddle of fuel on the inside of the hot manifold turns into vapor and also cause a flooding condition making it hard to start.
created from a hot engine. Your fuel level in the Q-jet maybe too high and with a hot engine the carb becomes heat soaked which expands the fuel inside the carb causing it to overflow into the primary tubes and down into the hot intake manifold. The puddle of fuel on the inside of the hot manifold turns into vapor and also cause a flooding condition making it hard to start.
