57 Buick - too much fuel at start when warm?

[lancemb]

I recently drove my recently resurrected 57 RM and had a bit of an issue. The car seems to run great, except that I noticed when shutting it off and then trying to start it soon thereafter it seems to be flooding out. This happened last weekend and when I let it sit awhile it started right up; I took the air cleaner off and the carb seemed to be soaked with gas. I purged the pedal and let it sit about 15 minutes and it started right up. It is as if plunging the gas pedal down the small amount required to start it is flooding it out when it is already primed and warm.

Has anybody else had this issue? Is the carb adjusted for it to run a bit rich to begin with maybe? Although I am very familiar with the car on other levels, I am just getting up the curve on the mechanicals.

Help would be appreciated!

[Guest pfloro]

Hello lancemb:

I ran across this information while reading another related post:

<span style="font-weight: bold">Difficult starting of a hot vehicle from 5 minutes to an hour after the engine has been operated, can be caused by the volatility of modern fuel. If you have this problem; try using the following method to start the engine: DON’T touch the footfeed (VERY important). Crank the engine over from three to 5 seconds (different vehicles will respond to different times); and then GENTLY (so as not to activate the accelerator pump) press the footfeed approximately 1/3 of its travel. The engine should start, and may run rough. Run the engine at a high idle for about 10 seconds. This issue is caused by volatility of modern fuel. Once the engine has been shut off, the gasoline is heated by the latent heat of the engine, and percolates the fuel from the bowl into the throttle area, forming a mixture that is too rich to fire. If you push the footfeed to the floor (as has been the traditional method of “unloading” a flooded engine) the gasoline continues to flow into the engine (again due to the volatility). By not touching the footfeed, you do not open the throttle plates, and the engine will pump the overrich mixture out of the tailpipe. Once the overrich mixture has been alleviated, gently opening the throttle will allow the engine to start.</span>

The link to The Carburetor Shop troubleshooting page...

Perhaps it is the higher volatility of today's gasoline which is causing the trouble.

Please let us know if this procedure helps.

Paul

[Caballero2]

I assume that this is a Rochester carburetor. If it is so, then I have little to offer. However, if it is a Carter AFB, then the early 1957 jobs had a problem very similar to the one you describe. As a fix, Buick did much the same as our modern recall. They replaced the early AFB with a new and improved one. I had this problem with my Caballero and when I replaced the early model Carter carburetor with the later one, problem was gone.

Dan

'57 Roadmaster 76C

'57 Super 56R

'63 LeSabre 4467

[JohnD1956]

I would check the choke heater tube. What may be happening is the tube may have rotted out ( especially in the back where it goes into the exhaust manifold) and the heat is not sufficient to cause the choke to fully open. While driving the choke may be held open by the force of the air being pulled down the carb, but once turned off, the choke could be closing again and causing the flooding condition.

[lancemb]

Hello and thanks for the tips. I will see how it goes this weekend; I will check the choke tube first. In response to the suggestion about not using the footfeed, the problem is that the ignition is tied in to the throttle, so I cannot start it without depressing the throttle a little. I thought maybe I could wire a toggle switch under the dash that would go directly to the ignition to accomplish this, but was hoping it wouldn't be necessary.

I am not sure which carb it has at this time (haven't brought car to its final home yet so I can't go check) but I really would prefer not to switch the original carb. When my father last drove the car (1977), he said he never had this problem...

I'll report back what I find; in the meantime any other suggestions would be helpful.

Thanks!

[Aaron65]

I think you'll find the gas volatility problem is your problem. I tied the exhaust heat riser shut (so no heat to the carb) and lowered my float about 1/8 inch. It helped but it still starts hard hot. Not 15 minutes, but it takes 3-10 seconds to start sometimes.

[Caballero2]

Aaron65 is probably right. The fuel today is not worth the price we are paying for it. I would try some octane booster. I like real lead in my old engines and use it even in my '49 Ford 8N tractor with good results. It is sold by the quart and has been advertised in the bugle. The vendor is Jack Podell.

Dan

'57 Buick 76C

'57 Buick 56R

'63 Buick 4467

'57 Oliver Super 55

'57 John Deere 3010 (Diesel no lead here)

'49 Ford 8N