Holley flooding at idle

[Jerry Weidner]

66 coupe 427/425 HP, 4speed. Stock engine. I finally got the car running good after chasing my tail for weeks trying to get the timing set, turned out to be dirty air passages on the carb, Go figure. brand new Holley replacement carb.
Now the cars runs great except after it warms up after driving for 5-10 minutes it STALLS when idleing. It is flooding out as I have to put the gas peddle to the floor to get restarted and the primary butterflies are wet when I shut off the car and look down the carb. I have lowered the float level as low as it will go, I took the body off and checked the float operation and it looks ok, no binding. I also put a heat shield on the intake and a heat spacer under the carb, still does the same thing.
Looking for suggestions what to check first.
Power valve is correct 4.5 , car dies when turning in screws so I dont think its leaking.
Can the fuel lines be getting that hot that they would boil the gas?
Fuel pump? It is a stock fuel pump. What are other signs of high fuel pressure.
Bad metering block?

Regards,

Jerry

[Phil P.]

check for FOD on the main jet

sometimes there is residual dirt or ? that will hold the main jet open enough to cause flooding---good luck,phil

[Clem Z.]

the 4.5 PV is not correct BUT that is not your

problem.lower the floats till the fuel level is about 1/16" below the float bowl opening.

[Jerry Weidner]

Re: the 4.5 PV is not correct BUT that is not your

Clem,
That is the first thing we did, still have the same problem only after it heats up. It will idle for the first few minutes then when hot it floods itself out. I lowered the float level down in 2 notch increments over several days and continue to have the same issues.

Jerry

[Clem Z.]

Re: the 4.5 PV is not correct BUT that is not your

i would remove the float bowls turn them upside down and pressurise the the needle/seats with 5/6 PSI of air and see if you have a leak thru using a soap solution. also check the floats for containing gasoline by shaking them. if the carb is brand new warpage should not be a problem but if it is a rebuild i would check all the flat surfaces for warpage. also i would recommend blocking the heat riser crossover in the intake manifold to get rid of the excess heat the carb sees. you will lose the heat to the choke but just disconnect the choke rod. if it is a corvette carb the bowl vent should be cut on a angle to allow the proper venting of the float bowls. holley carbs with flat cut vents will cause excess pressure in the float bowls because the top of the air cleaner is too close to the vent tube opening

[Paul G.]

Re: the 4.5 PV is not correct BUT that is not your

I just went throught this on my 65 365hp. Engine would stall after a couple of minutes of running, fuel would pour out of the sight plug holes on both the primary and secondary. Adjusted float level way down and same situation. At first I thought the fuel was getting too warm but I let the car sit over-night and fuel poured out of the sight plug holes on a cold engine, idling. Checked cranking fuel pressure and saw 8-10 PSI........bingo, high fuel pressure was the problem.

[Gerard F.]

Re: the 4.5 PV is not correct BUT that is not your

Jerry,

If it has side hung floats, check the looseness of the floats on float pivot pin, as to whether you have a back and forth movement. With too much slop here, the floats would tend to move back and forth under accellation and braking (especially braking) and possibly hang up on the metering block or back of bowl. I had this happen to me on a 3810, with flooding into the secondary side after a hot run, from the float hanging up against the metering plate.

I just bent the float back and made sure the float was tight in the pivot and that solved the problem.

In any case, I think it is either the floats hanging up or the needle seats not holding under gas pressure. Could also be blocked vents in the air horn, with fuel siphoning into the intake at low speed and after shutdown.

Glad to see you back and on the job, Clem. I tried to cover for you while you were in Carlisle.

Jerry Fuccillo
#42179

[Jerry Weidner]

Re: the 4.5 PV is not correct BUT that is not your

I changed out the power valve for a new one today and also changed out the float in the primaries for a new one , wrapped all the fuel lines and carb with high temp heat wrap , drove it for 10-15 and the problem started again? I am taking it back to the mechanic on wed, I give up. I think it is a bad carb, only happens when it gets heated up but I have wrapped everything with high temp heat tape , put on on heat shield and gasket and it still floods out after warming up, by the way the choke is disconnected because of the heat shield gasket I installed.

Jerry

[Clem Z.]

thank for covering BUT mrs clem never said

a word. she can sure keep a secret.

[john daly]

Re: the 4.5 PV is not correct BUT that is not your

Jerry,

I am having the exact same problem with my 67 at the moment. I took Clem's advice and tested the needle and seat with some soap and a air hose. The needle and seat held air but air was leaking around the valve seat where it screws into the bowl (to set the bowl height). It seals to the bowl with an O-ring which was old and cracked. I replaced the O-ring and retested with no air leak.
I'll put in back on the car tomorrow.Hope this helps.

John

[Gerard F.]

On the floor laughing, Clem *NM*