428 Dual carbs - flood hot engine

[rcobra427]

I have a 428 in my Cobra with a factory 427 dual quad intake and 600 Holleys that I bought new in 1983. Yes, I've had this car that long.
Lately, when I turn off the engine when it's hot, the fuel in the carbs leaks from the venturis, down the manifold, causing the engine to flood when I try to restart it. If I wait an hour or two, it starts right up. If I try to restart it after 10 or 15 minutes, I have to hold the pedal down to get it going. It's getting annoying. I rebuilt the carbs a couple years ago, and it runs great otherwise.

What causes this, and how do I fix it?

Rick

[Rick Parker]

A couple of distinct possibilities:

1. Float levels are a little high.
2. Needle & seats are faulty and will not hold the residual fuel pump pressure. Current levels of Alchohol in the fuels will attack the rubber on the tips of the needles & seat assy.

[Ron61]

What Rick said is the most likely problem. Also do you know if both cabs are leaking or is it just one of them?

Ron

[DanEC]

I also second float level and/or bad needle/seat. I will add that it also may be fuel boiling over in the float bowl when the engine is shut down. Strange it would suddenly start doing so unless the engine is running hotter than it used to or the fuel line has been re-routed or something. If you have room you might install an insulated spacer under the carbs. Also, check coolant temperature when hot. It could also be a re-formulation of ethanal in your local fuel that pushed things over the edge.

[Archrms]

I had the same problem with my carbs last year. Rebuilt both of them and the leaking stopped. Also, try running an additive to help the rubber parts last longer due to the Ethanol in the fuel after you rebuild them.

[rcobra427]

Thanks for the answers. I looked at the float levels, and although they seemed OK, I lowered them all about half a turn. If I continue to have the problem, new needles will be installed. The coolant temperature is about where it always runs, 180 -190, unless of course I have to sit at a really long red light or something, it might hit 200. That shouldn't be a problem. As far as the ethanol fuel goes, I've always used it, but I see now there are some gas stations around here selling 90 octane ethanol free fuel, for the boaters. I live in Cape Coral, FL and I think there are more boats than people. I'm going to start using that in the car to see if there's any difference.

Thanks again for the responses.

Rick

[acmjg]

Hello Rick!

Let me know where you find the ethanol free fuel. Good to see you here!

Anthony

[davecobra]

Rick I run a dual quad 428 also, I found that I could squeeze a 1/2 wood spacer between the carb and manifold and it cured my problems here in the texas heat, it will depend on how much room you have between the hood and air cleaner.
David

[rcobra427]

Hey Anthony!

I was on my way to Naples last Saturday and I remember seeing a big orange sign in front of a gas station that said "90 octane ethanol free rec fuel available". Now I just have to retrace my route and find it again. I'm pretty sure it was right over the bridge in Fort Myers. When Ford's Boat House opens down at the Cape Coral Yacht club, they're going to start selling fuel again. We should be able to get it there too.

Rick

[rcobra427]

No room for 1/2" wood spacers, but I did put several thick gaskets under the carbs.

Rick

[PANAVIA]

with the heat soak of shutdown it might be pressurizing / boiling gasoline. Carbs probably need a fresh going through. -==-=

[davecobra]

Rick take some clay and make little stand on the air cleaner at the closest contact points with the hood, then close the hood and check your clearance, you might be surprised that you do have room for at least 1/4 inch spacers.
David

[68pony]

I had the exact same problem, I had the Holley 950DP rebuilt , new needle and seat and floats, presto no more flooding. (427, small block) Starts instantly cold and hot now , mine would flood even after sitting for 40 minutes after turning off engine, if I stopped to buy fuel (5 minutes) would start no problem only if left sitting for a while, carby rebuilder said there was a lot of dirt in the bowls so I changed both my fuel filters at same time 1 between the tank and fuel pump and 1 just before carb , I would change your fuel filter aswell, hope this helps.