Sticky float on 850 DP?

[HHStang]

Sorry for an amateur hour question, but...

I've been fighting 5 weekends with my Holley 850 DP and I read all the symptoms as a sticky float, but.....

The car was running fine (maybe 10 miles on it), when, in the garage fortunately, demons possessed it or something,

Here is what happens:

-Car will start and run well, then start missing, then die, then not re-start,
- Gas is running down carb throat from vent tube and squirters and plugs foul,

Here is what I've looked at or done:

- replaced both needle/seats (center hung floats),
-spay cleaned innards and replaced float bowl and body gaskets,
- Fuel pump is mechanical Holley with 6 or 7 lbs pressure,
- I swapped a brass float from an extra Holley I have and for a brief moment, it ran and didn't flood. I started again and, you guessed it. Same problem as before.

I clean plugs each time and have already changed oil and filter once with gas contaminated oil trying to figure this out.

HELP..........PLEASE........... IT'S KILLING ME..........

Thanks all.

 

[351w_swap]

sounds to me like you have too much carb for the engine. is the carb new?

 

[brianj5600]

Powervalve blown?

 

[HHStang]

Power valve

I though power valve was mid-range and up. ??? This is at idle. Thanks...

 

[brianj5600]

The can go bad and leak fuel all the time.

 

[brianj5600]

If it is a float/needle seat issue it should leak out the sight plugs. Do you have a fp gauge on it? I misread the original post, thinking it was not leaking fuel. I had to adjust mine down until the nut was barely catching theseat assembly.

 

[D.Hearne]

Put a regulator on it, 6-7 lbs is too much.

 

[HHStang]

This pump isn't supposed to need a regulator, but I'll try it. I have one from the former electric set up I had, so no harm in trying.

 

[pabear89]

Sounds like the needlevalve seat is too low.
If you screw it in too far when the float lowers to allow fuel in it hangs up the needle when the float rises and causes the overflow that pours fuel into the carb.

pull the sight plug and reset the levels so it just comes out of the bottom of the hole when you shake the front of the car.

PB

 

[iskwezm]

my 750 HP was doing the same thing.The needle and seat has something so small i couldnt see it, but it would run then sputter then start and shoot black smoke. I pulled the needle and seat a few times and cleaned them and would also trun the pump off and run the carb dry. After a few times it cleared out.

I also run 6-7 psi.

 

[HHStang]

Thanks!

I set the floats by the Holley book (bowl upside down- horizontal, and pencil from bottom).

Still think it could be a needle adjustment?

 

[D.Hearne]

Yea,, and still try a regulator, it doesn't take much pressure to overwhelm the float and sink it.

 

[HHStang]

It was a float problem after all this. The float was binding so adjusting it did nothing. One more lesson learned. Thanks all.

 

[hurt]

I've never opened one up - how do you fix it so it doesn't bind?

My 600 is doing the same thing on my 66. It never did it before I got it tuned and after I got the car home from the dyno (only revved it to 5000) I took it on a quick trip to the store and it sputtered and died. Took a little to get it started again. Limped it home and watched fuel pour out of the hole shown in this picture:

Called the dyno shop and he said it was a float sticking and to tap the side of the carb with the wooden handle of a hammer. He said it's normal for a new carb (mine's rebuilt) and it takes some breaking in but it'll stop. So I tap on it and sure enough it runs like a champ and away we went. My wife was not happy about taking it. She was right, it happened three more times before we got it back. I about beat the ***** out of it the last time.

Should I try to fix it myself or get another carb? I've swapped engines, transmissions, rewired the car, so I could probably do it but I have to wonder if it's worth it. I bought it rebuilt but who knows how good it is.

 

[D.Hearne]

Sticking float is usually the result of dirty fuel. Never had a new or fresh rebuilt carb with a stuck float. A bad needle/seat assembly will also do it.

 

[hurt]

Thanks, I may try my hand at rebuilding it. Can't get much worse.

 

[HHStang]

D Hearne makes a good point. It may just be a dirty needle/seat which is very common. Get a Holley book. This is pretty easy to clean/repair.

Are you sure the shop just didn't adjust your float (floats) too high? Before I tore it apart, I'd adjust it (them) down and see if the fuel stops coming out the top. This adjustment should be in most any manual.

Whichever side is pouring gas, loosen the nut (I think its 5/8") with the large screw in the center that sits on top of the float bowl. You might measure how high the screw is off the float body and write that number down before you go adjusting. Anyway, loosen the nut and turn the big screw clockwise and see if the fuel stops pouring. Do this all while its running by the way. If it stops, you'll need to do a more precise float adjustment that's covered in the repair manual. I don't have time now to explain, but try adjusting the float before you tear it all apart. Also, depending on how much fuel you've dumped into the carb, you might want to change the oil and filter. That gas has been pouring straight into your oil pan.

 

[hurt]

The shop only adjusted the A/F screws, the carb is the Non-Adjustable float one:

Holley 4160

I think I may have to throw on a fuel pressure regulator.

 

[HHStang]

oh. never seen one of these in real life before. You shouldn't need a regulator on a mechanical fuel pump system. Do you have an electric pump? Try popping the bowls off and see if you don't see debri in there. Look at the needle and seat and see if these is anything in there. If anyone used teflon tape in your fuel line, you'll probably find it in your needle and seat. Just loosen those four little bolts on each side and peak in. Worst case, you'll have to buy a couple bowl gaskets. Advanced, Autozone and Pep Boys all sell them.