Flooding during shutdown

[joeflip]

My 65 300hp just started flooding when shut down for a few minutes. Clears up a few seconds after restart but something is wrong. Never had issue before. Any ideas?

[AUTOHOLIC]

Originally Posted by joeflip

My 65 300hp just started flooding when shut down for a few minutes. Clears up a few seconds after restart but something is wrong. Never had issue before. Any ideas?

When you say flooding, do you mean that you have to hold the accelerator pedal down in order to restart it after it’s warm? If so, it sounds like fuel percolation to me. This comes from the ethanol and the gas today and there’s really nothing you can do about it. The best thing to do is to hold the accelerator pedal about 3/4 of the way down to get it to start and then you may have to read it a little to keep it running before it clears up. This is far more common in the summer with the summer blend of ethanol.

[joeflip]

Do you mean the fuel is seeping into the cylinders when it's shut down?

[AUTOHOLIC]

Originally Posted by joeflip

Do you mean the fuel is seeping into the cylinders when it's shut down?

No. Percolation is when the fuel percolates in the carburetor from the heat after you shut it off. When it percolates it causes this problem of starting.

[roadpilot]

If it is peculating some guys put a spacer between the carb and intake.

[Yadkin]

Rebuild the carburetor.

[AUTOHOLIC]

Originally Posted by Yadkin

Rebuild the carburetor.

That won’t cure the percolation problem. It’s just a problem of our times with this ethanol fuel.

[LATB]

Originally Posted by AUTOHOLIC

That won’t cure the percolation problem. It’s just a problem of our times with this ethanol fuel.

Don’t use the ethanol fuel.

[AUTOHOLIC]

Originally Posted by LATB

Don’t use the ethanol fuel.

That’s great if it’s available to you. In my town, there’s one station that has it and it’s more expensive than premium. In the summer of2018 when I did a route 66 road trip from Chicago to California I had a lot of problems with percolations on the trip until I got to Oklahoma, where I was able to buy non ethanol, gas there and through Texas. As soon as it was not available again. The problem started right back up. That was in my 65 which did not have any type of thermal barrier between the intake in the carb. I did more than half the trip with the 65 but when I reached Arizona I switched to my 57 that I had at the time that had dual quads on it with thermal barriers on both carbs, but it didn’t seem to make much difference.

[Yadkin]

Originally Posted by AUTOHOLIC

That won’t cure the percolation problem. It’s just a problem of our times with this ethanol fuel.

I didn't get that from the OP's remarks. I see another poster addressed that, thanks.

[Dreaming 60's]

Seems all the newer fuels percolate or dry up and require extended starter run time with the old carbs, at least my cars and my area (OKC).

I always buy non-ethanol fuel, but if the car sits for more than a few days, both the 62 (AFB) and the 66 (Holley) require additional starter time to get fuel to the carb and then start up.

Once I go past 3-4 weeks, the 62 can take 4-5, five second bursts of the starter and then it starts and runs smooth. The 66 can take 3 bursts. Both carbs are good with recent OH's and no running or idling issues.

I don't remember this problem back in the day, but back in the day my cars were driven daily or every other day. Maybe fuel always percolated away and I just never realized it.

[LATB]

Originally Posted by AUTOHOLIC

That’s great if it’s available to you. In my town, there’s one station that has it and it’s more expensive than premium. In the summer of2018 when I did a route 66 road trip from Chicago to California I had a lot of problems with percolations on the trip until I got to Oklahoma, where I was able to buy non ethanol, gas there and through Texas. As soon as it was not available again. The problem started right back up. That was in my 65 which did not have any type of thermal barrier between the intake in the carb. I did more than half the trip with the 65 but when I reached Arizona I switched to my 57 that I had at the time that had dual quads on it with thermal barriers on both carbs, but it didn’t seem to make much difference.

Non ethanol is readily available here. I assumed it was elsewhere.

Question:
Is it better to up the octane in the non ethanol with an additive? or use an additive to offset the ethanol in the premium?

[AUTOHOLIC]

Originally Posted by LATB

Non ethanol is readily available here. I assumed it was elsewhere.

Question:
Is it better to up the octane in the non ethanol with an additive? or use an additive to offset the ethanol in the premium?

Of the seven fuel stations in my town only one offers non ethanol and it is 87 octane atthe Maverick station. So on my 65 with 11 to one compression pistons and aluminum heads, I have to use 91 octane ethanol fuel with VP racing fuel additive.

Depends on the octane rating of the base fuel that you’re using whether it’s ethanol or non-ethanol fuel. If you need to up the octane start with the highest octane rating, regardless of whether it’s ethanol or non-ethanol.