Hi guy's i have a 600 HOLLEY on my 350 chevy, carb is new i am getting gas sometimes floding the back bowls and down the side's. Took carb apart checked fuel float's , needle and seat's look good no junk in the inside that i could see.I am running a stock fuel pump, in and out, nothing hi volume. fuel pump was new. This has happened 6 or 7 time's before to me, any suggestions? PINCHER
Pincher, quick way to check if it is a needle/seat issue, swap the front to the rear and rear to the front then see if the front now floods. If so, replace the bad needle and seat. If not, swap out the floats and see what happens then. Sometimes switching them will help sort it out...sometimes switching them even fixes the issues!!! Don't know why/how, but sometimes it does.
Check fuel pressure. I've seen stock defective pumps (new and used) go as high as 15 PSI. Should only be 5-7 PSI. Also, see if the float's "sunk". The brass ones can get a pinhole and fill partially with fuel. Remove it and shake it
I wished you lived a little closer... I'd come by and fix it free of charge...... Let me know if you have a bad float... I'll try and mail one out too ya!!
Thank's everyone, HOLLEY does not put the brass float's in anymore, at least not in the 600 vac. secondary. they are made of some kind of plastic. I think the problem might be in the fuel pump, even though it is new.I agree also that it may be pushing to much psi,and over flowing the float's. Will try a new fuel pump tomorrow. THANK's everyone. >>>>>>PINCHER
Put a fuel pressure guage on it first ,,,my two 600 Holeys on my blower will NOT take more than 5 psi with stock needle n seats ,,if you have more pressure than that ,,spend your ,money on a fuel pressure regulator ,,adjust it to 4.5 psi ,,problem might be solved ,,
I had the exact same problem with a 600 Holley and 350 motor and it was the new Summit fuel pump (stock style but tested at 9 PSI) with too much presssue. I bought a fuel regulator out of Autozone (looks just like a Holley one) for $19.95 and with my Craftsman compression tester kit found out the pressure and set the regulator to 4.5 pounds and that cured it . Update= Autozone doesn't carry the $20 one anymore but Summit carries them for about $25 bucks.
Put brass floats in and change Metering valve ,Common problem ,Thats how I fixed mine ,A few times ....Oh and by the way Its the float one fingernail scratch and their done ,Some coating is applied to float .
keeping my eye on this one..have the same problem with both a 600 and 750 both vacuum secondaries,and a carter electric fuel pump
agree with the fuel pump issue..New carbs are close...is it a 80457 carb?? (electric choke, vac. secondary) take screw out and check float level. That will tell you quite a bit... I've seen stock pumps that come from the parts store put out 8-10 psi, WAY TOO MUCH
Thank's carcrazyjohn and Broke Dick, I plan on replacing the plastic or whatever they are made out now with brass float's, and also both needle and seat's, if this does not solve the problem plan on regulator........PINCHER
I have two 600's on mine with a holley mechanical pump. I have on of these with a guage. http://www.summitracing.com/parts/SUM-G3120-1/?rtype=10 Seems like the guage usually reads 6-7 psi. I'm glad....i really didn't know how high was too high.
If it is the carb that has the needles and seats you can adjust from the outside make sure that the float bowl isn't stripped where the needle screws in. I just ran into that on a Holley I have and had to replace the bowl.
I have a Holley Blue Elecric Pump on my T ,,it puts out 9plus psi ,,so i have a pressure regulater to tame it down to 4.5 psi to my dual 600 Holley carbs ,,A fuel pressure regulator doesn't effect fuel volumn ,,just pressure ,,
I had a ton of trouble with daily changing float levels (Road Demon Jr. 525 - a real pain in a$$ problem). Friend suggested I change to steel needle and seat arrangement - get rid of "Viton" tipped needles. It worked right away - the "Viton" was not compatible with the local gas formulation - alcohol or additives made the rubber sticky. Used Holley .130's (cheap for two) - have twice the area of a .097 and I expected trouble with the fuel pressure (5.5 psi on gauge). So far, no worries - set it / forget it.
Any time you change fuel pressure, you change volume. If you push a fluid through a specific sized line, at 10 psi, you'll get a lot more volume than when you're pushing it with 5 psi.
YES tis true the bIGGEST obstacle to fuel volume is the regulator. I now dont use them but use 2 Carter pumps (6 psi on a good day) which gives a free flow value of 140 . Pushing fuel throgh a 1/2 inch line to a tiny 1/4 " opening sealed by a ball and spring and expecting volume is I have decided absolutley nuts. i came to this conclusion doing volume tests on a serious race car which was running out of fuel even though the math said it should have had more than enough. (1/2 pound of fuel makes 1 HP for 1 hour)Discovered once you put a regulator in front of the flow that actual flow goes in the toilet. Also regulators creep unless they have a return line and the pressure varies from run to run. Now I dont worry about it. Just flip the switch and enjoy. Many many years ago Vic Edebrock used to come to Toronto for clinics, He brought an old carb guy with him who spoke to us. The guy always encouraged us to run two Sw or carter pumps with two lines as opposed to a single line big pump with a regulator. I thought he was nuts back then. Why everyone ran a big Holley pump with a huge line and regulator but when you actually sit down and go through the whole mess you begin to realize this fellow was a ahead of the curve. Don
Good info there guys ,,,but I was told by Holley Tech a couple years ago ,,to keep Fuel Volumn constant with two carbs ,,one must run two Regulators ,,one per carb ,,any thoughts there ???
One thing I haven't seen mentioned. If you have the phenolic float, don't touch it with bare fingers. The oils from your hand will eventually break down the sealer they use on them. Seen it a few times, I could actually see the guys fingerprints on the float.
I've always heard this, but I do know that if the fuel pressure stays constant in the fuel log supplying the carbs, the volume will stay constant, and supply the same amount of fuel to both carbs. I'm running a single regulator on my avitar, with no problems. Often wondered why Holley, and all the other regulator suppliers, build 2, 3, and 4 port regulators. Two makes some sense, for dual inlet carbs, but why 3, and 4? Even a single, dual inlet (Holley/Demon) should probably have a regulator for each end, so they'll both get the same flow.
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