New holley 750 problems.....need help

[rsd859]

I'm the 2nd owner of this Holley, traded straight across for a tree stand on craigslist, it was flooding real bad. So I changed the o rings on the needles, changed my oil, pulled all of my plugs and cleaned them they were coal black and soaking wet.

So I started it today checked out float levels (good), 5" of vac. There was lots of white smoke on the drivers side tailpipe, it cleared up after 3 or 4 minutes. Put it into gear, and the idle didn't drop.....I thought that was weird. So I turned it down slowly and it died. I immediately stuck my face over the carb to see if there was fuel dripping and I didn't see any, but there was lots of vapors comming out of the primary side. I also noticed that the fuel pressure was holding in my clear filter, yesterday it bled off fairly quickly.

I'm wondering if my spark plugs are shot, or if there is still some tweaking left to do on the carb. Any help or guidance would be greatly appreciated! Thanks, Rich

 

[mopar367]

How is the power valve? is it the right one? Did you blow it by having a big backfire when tinkering with the carb?

 

[rsd859]

I have #68 jets, and a 3.5 pv I am happy to report there were no backfires and this Holley has the check valve.

 

[mopar367]

I would keep messing with the carb. I don't think its your spark plugs.

 

[rsd859]

Well, the reason why I think it's the plugs is I tryied to start it back up after it died and it just turned over, didn't even act like it was getting fire.

 

[mopar367]

probably flooded, double check for a stuck float. or too high of a float level

 

[rsd859]

Well, I put a fresh metering plate gasket on this morning and while it was off I hit to with the air hose and also the main body. And I didn't get the vapors comming out of the choke tower. After I shut her down, so I thought I had her fixed. I went in the house did some things came back out and noticed that the side of the intake was wet. So I touched the peice of gasket that was hanging out and it's totally saturated with fuel. So now what? Floats are set, pressure is good, I don't know what else it can be.

 

[Street fighter]

Are you using the right intake with the correct carb?Are you sure you have the floats ajusted correctly. Did you remove the sight plugs and adjust them or did you leave them in? I remove them, but I make sure I am on level ground.I start by lowering the gas in the sight glass lower than the sight glass.start the car and raise the level slowly until you can just see it in the glass, watch and see if it gets higher, if it does you may have too much fuel pressure or trash in one of the needles.remove them one at a time and check them for trash, I usually blow through them.reinstall them just as we stated before.starting low and coming up slowly until you can just see the gas in it, if it stay running you can let it stay there and see if it flows once shut off. If it don't flood you can raise the level until it barley spills out.If this don't work you may need a rebuild or just get a new carb. I build the holley all the time easy to do.

 

[Budnicks]

Might need more info, for someone to help successfully... What specific Holley Carburetor is it ??, Are you sure you have the float adjusted correctly ??, hopefully you don't have a crack somewhere either... Vacuum leak maybe... Don't over-tighten the screws on the bowls or base plate either & crush the gaskets, causing fuel leaks or crack/break/warp something... Is it a center pivot float or side, a 4160 or 4150 style or what ??, Use the blue gaskets & make sure you have the correct ones, for the specific carb, they aren't all the same... kind of sounds like crap in the fuel system, causing intermittent problems.... also What kind of fuel pump & what pressure is the pump putting out ??, electric or mechanical pump ??, any regulator ??, do you have a fuel pressure gauge inlne to reference ??, most Holley style carb needle & seats, for the fuel bowls, can't handle over 7psi max, with out specially needle & seats... I'm not sure if any of this will help, but I would highly suggest, you get a book/DVD on "how a Holley Carb works" & how to properly tune them... Good luck

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what kind of vacuum does the engine make at idle ??, a general rule of thumb, is a power-valve #, 1/2 of what your vacuum is...

 

[Budnicks]

very well could be fuel-fouled plugs on-top of the carb issues making it hard to start, are they new or old plugs, I say, just change all of them if they are old, it couldn't hurt anything...

 

[rsd859]

Alright guys, floats are properly set and they are center pivot, there is no trash in the bowls, the carb is a 4160 electric choke, shiny finish #80508-s yes the gaskets were smashed and I replaced them. I'm very familliar with volleys, but this one has me baffled. I'm running a mech. fuel pump, the 650 I had on previously had no problems with flooding so the psi shouldnt be too much for it to handle. I have 5" of vac at idle, I got the 3.5 pv because it was the smallest one oreillys had and on the 650 I was running it did just fine.

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Also no vac leaks

 

[rsd859]

Put new plugs in, today but I didn't start it yet, wanna try to fix the flooding, before I ruin another set of plugs.

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I've also sent an email in to Holley.

 

[Budnicks]

If your very familiar with the "Volleys"...LOL... sorry I couldn't resist.. you should well know, that the float level &/or the needle & seat is what regulates fuel levels... Maybe ask the original owner of the carb, what he changed, maybe it has the wrong metering block/blocks & gaskets or some other weird/strange issue... do you know the guy ??... Or even maybe completely rebuild the damn thing, it's not that much $$$ for a complete re-build kit, than you will absolutely know you have all the proper gaskets, in the proper place, if you know "Holley's"

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I'm running out of ideas

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are you sure it's a fuel problem ?? making it not start, you need all three, compression, fire & fuel

 

[rsd859]

Thanks Bud lol! I was typing on my phone when I wrote "Volleys". I contacted the orginal owner and am still waiting to hear back.

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[Budnicks]

Yeah I figured as much...LOL... accelerator pump leaking maybe ?? throttle shaft worn & leaking maybe ?? fuel supply line leaking ?? I wonder if the air-bleeds are clogged in the metering block ?? also does fuel come out the vent tube on top of the carb ?? {perfect situation for the needle & seat sticking or bad}, idle passages clogged ?? either of the last 3 could/would possibly cause flooding or bad running issues... like I said "I'm out of ideas", really just spit-balling now

 

[rsd859]

I blew out the air bleeds and every hole I could find. The metering plate gasket I replaced matched up perfect but that doesnt mean anything, it could be the orginal owner put the wrong one on and I matched it. Im trying to find which gasket is the correct one.

No fuel comes out of the vents, Im leaning towards the throttle shaft, or a crack some where.

 

[rsd859]

Jegs has a rebuild kit for 20 bucks, I think I will just go thru the whole thing and see what happens.

 

[Street fighter]

what is all of that under the base of the carb? How many gaskets do you have on it. Also is that a adapter plate under the carb?Is that gasket sealer on the gasket? If you are running a adapter plate they a bad at causing vac. leaks.and anything other than a good base gasket will do the same.If I were you I would rebuild or buy a new one.Change plugs and try again.If you keep running the car with the flooding problem you my find yourself rebuilding that engine.I am willing to bet you have a bad vac. leak.And fouled plugs.

 

[rsd859]

I was waiting for that question, Its a mr gasket phenolic spacer, then there is the holley heat shield, w/ a 3/8 thick gasket. I dont use sealer on my carb gaskets. I put new plugs in yesterday, and only started it once and it ran for maybe 4 minutes while i checked float levels, so im hoping my plugs are still good.

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Cant see it real good but the heat shield works wonders in the summer time. Best 30 bucks i spent on the engine.

 

[rsd859]

Alright guys, I think I found the problem. When I switched pwr valves the gasket wasn't seated around the valve properly and was slightly canted causing the leak. Getting ready to put it back on the car and fire her up. I'll post the results of the start up.