MY 1970 CHEVELLE DRINKS FROM A HOLLEY 3310-4 VACUUM SECONDARY 750 c.f.m. with a K&N AIR FILTER.MY PROBLEM IS IT LEAKS INTO MY ENGINE OVERNIGHT AND MY BOWL IS EMPTY. I NEVER HAD A PROBLEM UNTIL I CHANGED MY POWER VALVE FROM 6.5 H.G. TO A 4.5 H.G. MY ENGINE IS A WORKED 350 WITH A LUNATI BRACKET MASTER CAM 230-230 AT 50th WITH A 110 LOBE SEPERATION,VACUUM GAUGE READS BETWEEN 12 & 13 H.G. AT IDLE. FULL MSD IGNITION,HEADMAN HEADERS,2.5 FLOWMASTER EXHAUST,4-SPEED,12 BOLT W/ 331 OR 355'S (NOT SURE).WOULD THIS HAPPEN BECAUSE OF POWER VALVE OR MY NEEDLE&SEAT.

THANKS FOR HELP AND KEEP THE RUBBER HOT

[This message has been edited by MIGUEL (edited 10-01-98).]

[This message has been edited by MIGUEL (edited 10-01-98).]

When you changed the Power vaule did you clean the metering block gasket and clean the surface throughly. I also used the poly reuse able gaskets on the bowls of my holley and I never had a problem with them leaking. I run a 4.5 power valve and Earson Viking 100 cam (about 9-10 H.G. of vac at idle) with a 650 dbl. pump with man secondarys. I have rejetted the carb about 5 times since I got the gaskets and they never leak.

I know this sounds stupid but did you remember to install the power valve gasket and torque it to specs?
Also make sure the metering block gasket is in good shape.

Mark

THANKS FOR THE REPLIES.
ALL SURFACES ARE CLEAN AND ALL GASKETS IN PLACE.TODAY I WENT AND PURCHASED A HOLLY RENEW KIT WHICH HAS EVERYTHING TO BRING IT
BACK FROM THE DRIPS.CARB IS 5 YEARS OLD,GUESS IT'S TIME.
MIG

I have the same carb, and I am having a problem of SEVERE flooding. Can only start it floored, and need about half throttle to keep it going. HISTORY: Last week, primary float sunk. Bought an AED kit and rebuilt it. Put it back on and flooding as bad as before. I just went out and pulled the front block, and tightened the power valve, as I remembered that it had the plastic gasket, & I may not have gotten it tight enough. Rechecked the float level, top of float just about sight plug level. Still dumping gas out the primary venturies. I re-checked all mating surfaces on the block & bowl, with the gaskets and everything looks like a good fit.

I haven't rebuilt a carb before, and I didn't have a referene book, but it's a pretty simple piece of hardware. I compared all the old gaskets to make sure I had an identical match.

Another irritation is that it spews gas through the needle adjuster nut. The kit has plastic gaskets for the nut and set screw. I can't physically tighten it any more and the bowl surface is not obviously burred. Probably just a little more uneven than the gasket will allow. Either that or the pressure is excessive. Don't have a guage though. Do fuel pumps fail & cause excessive pressure? The secondaries are fine(No Flooding). May have to get a conventional type gasket for the adjusters.

Anyway

What the h*** could cause this severe flooding??

Any ideas would be greatly appreciated.
Thanks
Roy

I have an 850 double pumper that drains the secondaries. It starts easily but it looks like a crop duster for the first 30 seconds or so...and stinks like a burning oil derrick. Quite embarrassing. I can't figure out where the leak is. I really don't want to take the damn thing the whole way apart because it'll probably never be the same after that.

PS to Roy-- if a mechanical fuel pump fails you either get little or no fuel pressure, or gas in your oil, or both. Did you replace the needle and seat?

Both of you guys may have plugged idle air bleeds in the metering block. This would allow fuel to siphon out of the bowl. Try blowing them out with compressed air or cleaning with a BRASS or COPPER wire. No guarantees, but that's my off the hip diagnosis. Bryan

Roy go for a stock (Holley) renew kit. I did, and everything went together easy. No more problems. Sounds like needle & seat is stuck (dry o-ring). When you replace apply light grease to protect o-ring. Use the paper gaskets for float adjustment screw. Use very little vasalin to coat gasket, this helps gasket from binding and I get very little gas spray. Hope this helps.

Thanks to all for the thoughts. Worked on it more today. The float level is under control, it stays just below the sight plug while running. Still pours out the venturi's. I've taken the block off and shot carb cleaner through every passage to make sure nothing is blocked. Also blew through air bleeds. The power valve can't get any tighter and it's not blown. Gaskets match perfect. I just don't know what else to check. The only suspicion is the nylon, or whatever they are, gaskets. The needle adjuster gaskets leak, and I wonder if the power valve gasket could be as well. I can see that causing a rich condition, but it wouldn't draw excess fuel through the venturies, would it?

Either A) Buy a Holley kit and rebuild it again or B) take it to a carb shop and pay them to do it, or C) buy a new carb. Just really bugs me that I can't figure it out.

P.S. I went through my Haynes Chevelle manual and they didn't tell me anything I didn't already know, except they said that if there's a lot of miles on it, to just buy a new carb!

Thanks
Roy

I've seen this problem before on a freind's car. I think I remember him having the wrong metering block gasket for the carb he had. I don't know specifics, but I know there are at least two different kinds of gaskets when it comes to the configuration of the passages. I think his was blocking the idle circut all together with gasoline just pouring down the venturis. We switched gaskets and WAA LAA! worked great. Check that out. Make sure you have a gasket on the power valve also.

Ok, I have to admit stupidity. I have compared the metering block gaskets many times and confirmed all the holes line up. Somehow though, I didn't see that the cutout for the power valve had an extra notch that wasn't there in the original gasket, leaving the passage from the acc pump un-gasketed. DUH !!! I went ahead and put the old gasket back in and voi-la, no more flooding. Now I need to get a new CORRECT gasket for the thing.

I haven't been able to get it to idle quite right now, it dies in gear and backfires on quick throttle opening. I will have to get the right gasket and then work on the idle.

Thanks Jimmy and Miguel for making me check & re-check & re-re-check the gaskets.

Roy