dkleather

I'm working on my deceased brother's 72 350/200/4-speed, all stock, for his widow. He was the second owner since 1980. It's been sitting for six years but with a new battery and prime, started right up. There were no brakes so I bled and fixed them. Changed oil and filter. Drained the gas and put in new. Tank looked great inside. Car runs good so carb air mix is okay I think.
The carb (original) ran rich even when he was alive and he had it rebuilt twice but it still had exhaust that smelled like the choke was on. It still does stink! And the choke is full open after warm up.
I'm thinking the first owner may have messed with the jets inside the carb which has caused the problem ever since he owned it and were not replaced by the rebuilders. Is there a way for me to check this? Can original size jets be purchased? Where should I start?

MelWff

have you started by adjusting the mixture screws on a fully warmed up engine?

dkleather

I have and they affect how it idles and revs but doesn't change the rich smell. Thanks.

midigike

When it runs and drives does it hesitate when you put your foot in it? What is it idling at, Rpms? Remember there is no catalytic converter to scrub the exhaust and it will smell like horsepower candy.

dkleather

There's no hesitation when I accelerate hard and it idles at 800 rpm as measured by the tach. I have a 64/327/300 and know that " no converter horsepower candy smell" (). This smell is much richer, similar to my 64 at warm up with full choke, but the choke is off. That's why I'm thinking something inside is dumping extra fuel while it runs warmed up. I don't know enough about the workings of these carbs to figure out what might have been altered by a PO, if anything, or what might be wrong to cause this.
Thanks.

71 Green 454

I would take a hard look at the float and needle valve. When mine ran rich, the original float stopped floating to shut off fuel. Or, you could have a bad needle valve or seat.

dkleather

Thanks, I'll check. Makes sense that those might cause extra fuel to burn. Dave

tfringo

That is the first place I would look. Make sure you get a float that will handle the modern gas and make sure it is not set too high.

There is a person on the internet that specialized in rebuilding all sorts of Quadrajets, stock and performance modifications. You would have to look them up. They have great right-ups on how they work, etc. They had the right parts and such and they were great at answering questions.

I would look closely at the power valve inside also. I don't think it would cause those symptoms but I would look at it anyway and rebuild it as well.

Look for signs of an internal gas leak. If you take it apart, put the main body parts on a flat surface and make sure they are not warped. People over tighten the screws and they get warped. Good news, you can usually fix them. That company that I mentioned had a fixture for that.

As I recall, you an take the air cleaner off while at idle and look down the primaries, it is possible to see if excess fuel is dribbling off the primary venturies. You can't see the secondaries. This is something that might help confirm your problem.

Good luck and let us know how it turns out.


Just adding this. Look at the spark plugs and make sure they are correct. I would consider using a slightly hotter plug. This is something I have heard others doing.

71 Green 454

I found my float problem by looking down into the carburetor and seeing excess fuel dribbling in. If you do replace the float and needle valve, I would also replace the pump plunger that can handle ethanol.

dkleather

Do I look while it's running or after shut off? Running, I assume? ThanksDave

tfringo

Just wondering if it still has its smog system on it. If it does, can you tell me the head stamps you see on the three bolts attaching the smog pulley. Sorry for the side question.

tfringo

Doing it while running. But some cars will do it after you shut them off. This is sometimes the gasoline smell that people complain about after shutting them off.

dkleather

The car isn't here for me to check. I'll look early next week for you. Sorry for the delay.
Sent you a PM.

tfringo

Thanks. I have a very complete 72 smog pump system for a small block. I will be selling it. I just need a few thing for it.

If you can get pictures of it or any numbers off the hoses I would appreciate it. You could send pictures of (509) 953-8992 of tfringo@aol.com Thanks

71 Green 454

Yes, with it running, I could see the plenty of excess fuel going in.

Good luck,

Dave

daustin

Sounds like the float sunk. A lot of the floats in the QJet are "polyfill" or "Nitrofill" and don't take well to the ethanol gas. I just rebuilt one for a friends 72 Buick GS 455 that the poly float sunk. Got a real brass float, carb rebuild kit with the blue or green ethanol accel pump that should take care of that problem for a long time.

Don

dkleather

Can I do that by only pulling the top off the carb? I know I can on an AFB like on my 64 but what about the Q-jet? Dave

71 Green 454

That's how I replaced my float in the early 80's, but now I remove it from the engine when replacing any parts.

dkleather

After posting that I thought about it and decided with my luck I'd probably drop some small part down inside and have to remove it anyway. I'll take it off. Thanks.Dave

MelWff

have you checked any of the ignition basics before removing the carburetor.
Have you checked the physical condition of the cap, rotor, and points?
Have you checked the plug wire resistance with an ohmmeter, 1k per foot of wire.
What spark plugs are installed, manufacturer and part#? Are they correctly gapped?
Did you check the point dwell?
Did you check the initial timing?