Trouble with brand new Holley Carb - Team Camaro Tech
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post #1 of 17 (permalink) Old Apr 6th, 06, 03:42 PM Thread Starter
 
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Trouble with brand new Holley Carb

Put a new Holley 4150 750 DP and Edelbrock Air Gap intake on last weekend and it seemed to be doing great. The last two times I have driven it though it has a problem. After I get it out on the highway and then slow to a stop it dies. The first time I started it back up and reved it up a few times and all was well. This time it acted as if it were flooded, I got out and pulled the breather and there was so much gas on the primary
butterflys it was pooling with more still coming out but from were I could not tell. After the gas drained down I started it back up a limped it home with what I could tell the carb was still dumping gas. When I got it home I checked it again and it was still doing the same thing. It acts like there is to much pressure and it is forceing gas out of the carb. After it cooled down it started back up and idled fine.
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post #2 of 17 (permalink) Old Apr 6th, 06, 04:17 PM
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Re: Trouble with brand new Holley Carb

float is to hi or piece of dirt in needle and seat///
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post #3 of 17 (permalink) Old Apr 6th, 06, 04:33 PM Thread Starter
 
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Re: Trouble with brand new Holley Carb

When adjusting the float level should there be gas spraying out from the adjustment nut?
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post #4 of 17 (permalink) Old Apr 6th, 06, 07:28 PM
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Re: Trouble with brand new Holley Carb

Quote:
Originally Posted by KC406RS
When adjusting the float level should there be gas spraying out from the adjustment nut?
It will until you learn the feel for doing it.

...Dennis

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post #5 of 17 (permalink) Old Apr 6th, 06, 07:48 PM
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Re: Trouble with brand new Holley Carb

Check the float level first,..the clear 'sight plugs' are great,..they keep gas in the bowl and not dripping on your hot intake,..but after the adjustment, I go back to the brass fittings.

If ok, you probably have too much fuel pump pressure and it's over-powering the needle & seat assy,..six psi is about max for a street carb. What fuel pump are you running?
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post #6 of 17 (permalink) Old Apr 7th, 06, 08:54 AM
 
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Re: Trouble with brand new Holley Carb

Does Holley make clear sight plugs?? If not were can you buy them to fit??
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post #7 of 17 (permalink) Old Apr 7th, 06, 09:24 AM
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Re: Trouble with brand new Holley Carb

yes floats too high
or fuel sytem pressure too high.
holley recommends 7 psi max.
clear plugs are avail. from summit or jegs.
sight plugs here:http://store.summitracing.com/partde...5&autoview=sku


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post #8 of 17 (permalink) Old Apr 7th, 06, 10:20 AM
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Re: Trouble with brand new Holley Carb

A word of caution when using the clear sight plugs, they soften up and deteriorate to the point where they either leak or fall out.

The blended fuels we get from the pump is the culprit.

Don ~ TC Member #15 ~
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post #9 of 17 (permalink) Old Apr 7th, 06, 12:51 PM
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Re: Trouble with brand new Holley Carb

To add to what ZZ430 said, clear plugs are fine to use as a diagnostic tool. But many guys have learned the hard way that you need to restore the brass plugs once you get things set.

Dave
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68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #10 of 17 (permalink) Old Apr 7th, 06, 03:53 PM Thread Starter
 
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Re: Trouble with brand new Holley Carb

Update.....

Made sure float level was not to high and even droped it so I could just barely see fuel. Took it out drove it around town for a good 30 min. and it ran like a top. When I got back close to the house I took it down an outer road for a couple full throttle blast. First one no problem, slowed down turned around were it had started flooding before all was well.
Second one got it up to around 80 and let off and slowed to 35 felt it stumble and as I slowed it died. Pulled to the side and I could hear the gas coming out. This time I could see were it was coming from, it was coming out one of the air bleeds on the primary side like a little stream. When I got it back home this went on after I shut off for a good five minutes. Called Holley tech support and they say it has to be the carb getting so hot it is bolling the gas and that is why when it cools down it works fine. The thing that gets me is the car runs no more then 180 when moving and 190 at a stop light, so why does it only do this when it has been run at higher speeds? They said to get a carb spacer and heat shield but I hate to do this without being sure.
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post #11 of 17 (permalink) Old Apr 7th, 06, 05:43 PM
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Re: Trouble with brand new Holley Carb

Ahh,..could be. Sounds like your EGR system is alive and well. Are you running headers?..or the original exhaust manifolds with a heat riser valve?

If you have a heat risor it could be stuck which will cause the intake and carb to get too hot.

If you don't have a HR, try a thicker carb gasket.

Or you can purchase and install an intake gasket set that blocks the EGR passage which is the best way,..a hot intake and carb are no good for performance.
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post #12 of 17 (permalink) Old Apr 7th, 06, 08:34 PM Thread Starter
 
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Re: Trouble with brand new Holley Carb

Headers, no egr. The carb is cool enough I can put my hand on it when I am watching the gas bubbling out. I would think if it was so hot it was boiling gas there would be no way I could put my hand on it. I think I will pull off the primary foat bowl and see if it looks like the float is sticking.
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post #13 of 17 (permalink) Old Apr 8th, 06, 04:54 AM
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Re: Trouble with brand new Holley Carb

ive seen guys using wrong metering block gasket have same problem.
ensure you are using the correct kit.
also the heat sheild isnt too expensive and itll give you a couple HP to boot.


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post #14 of 17 (permalink) Old Apr 8th, 06, 09:24 AM
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Re: Trouble with brand new Holley Carb

I don't see how an "Air Gap" manifold could possibly be heating up the carb to the boiling point. I mean, look at the pic of this manifold:


There's just no way for the heat to conduct all the way to the carb, especially not with the engine operating at only 180 degrees.

I'm kinda thinkin' maybe you got a fuel line with too much pressure, either from fuel pump or maybe the line is getting hot. Do you have a portion of the fuel line that is close to the exhaust?? That would certainly cause fuel pressure to build above 6psi.

If possible, drive car around (stay close to your garage) until the problem starts, then as soon as you start noticing the problem, get vehicle into garage, disconnect fuel line (careful of excess fuel spray) and hook the line onto a fuel pump pressure gauge. Then start car and let run for a few seconds from fuel left in bowls and see what the gauge reads.

Also, when you disconnect the fuel line, if there's a lot of excess high-pressure fuel spraying out, then that's a good clue the fuel pressure is too high. Keep fire extinguisher handy. Gas spraying on hot engine is never a good thing!

The problem really sounds heat-related, otherwise it would be flooding out at all times.......................

-

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970

Last edited by Chevy-SS; Apr 8th, 06 at 10:27 AM.
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post #15 of 17 (permalink) Old Apr 9th, 06, 06:13 PM Thread Starter
 
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Re: Trouble with brand new Holley Carb

It seems as though the problem is fixed. What I think was the problem was the gasket that seals the float bowl was pulled apart at the top and pushing down on the float. I am not sure but ever since I replaced it the problem has not shown back up. I am starting to think the car is messing with me after the carb problem was fixed now the starter will not disengage about 50% of the time.
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