QWKDTSN Posted March 18, 2004 Share Posted March 18, 2004 My car's been parked for just a couple of days, had no problems before parking it. Went and started it up today and have been having some weird problems... Essentially what's happening right now is this - engine is warm and should start up right away, but it takes a while to crank over. Cranking, cranking... eventually starts to catch... sputters into life. Then, idles normally for about 20 seconds or so. Fuel pressure normal, everything sounds fine... Then, I see a bit of gas leaking out from somewhere on the carburetor. It leaks out, then starts pouring, increasing in strength, across the front float bowl from either the gasket or from 'somewhere' underneath the lip the air cleaner is supposed to sit on. As this happens, the car begins to stumble - more gas leaking - running worse and worse - until it stalls with a FOOF of white smoke puffing up from the main carb barrels. It seems that WAY too much gas is pouring into the main barrels for some reason? The carb is a 4150 dp, brand new, never given me any problems... the car was recently dyno tuned and has been running like a champ. Haven't made any timing adjustments and the MSD, ignition et. al. seem fine. WTF is up with the carb? Way too much gas, sudden weird leaking that almost looks like an emergency overflow is opening underneath the air cleaner lip? Could this be caused by a blown power valve, or float level too high? Sticky float? Help me, fast! Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted March 18, 2004 Author Share Posted March 18, 2004 Checked the float level, it is perfect, tried lowering the fuel pressure from 5.5psi to around 4, same problem occured. Blew through both tubes sticking up (emulsion tubes? not clear on this) and they were both clear, spat fuel into the barrels. Something possibly blocked up somewhere else? What do you guys think? Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted March 18, 2004 Share Posted March 18, 2004 New Holleys should no longer have the power valve problem; the factory now installs a valve to keep backfiring from blowing them out. Front float bowl is secondaries, right? Ordinarily no Power valve on the secondary side. If nothing is leaking at the primaries, you only have one bowl to pull. Sounds like a float is either stuck, sunk, or you have a piece of crud between the needle valve and seat (preventing its' closing--- this is my personal favorite). With the needle valve held open the gas just keeps coming in, eventually flowing out of the carb at the lowest hole (May be the nozzle in the middle of the venturis). I don't think loose bowl screws would act like this, should just leak, but you might make sure before you pull it. Man I'm slow composing these things--oh, well. Those are just vent tubes that you blew into; you pressrized the float bowls (forcing gas out the center of the venturis, right?). Quote Link to comment Share on other sites More sharing options...
John Scott Posted March 18, 2004 Share Posted March 18, 2004 John Quote Link to comment Share on other sites More sharing options...
John Scott Posted March 18, 2004 Share Posted March 18, 2004 Correct, new holleys don't have the PV blow out problems of old. Front bowl is primary. A blown PV causes a dead rich condition, but won't cause gas leakage. A good needle and seat will hold 10+ psi. My bet is needle and seat. Take the screw off the needle and seat adjustment, pull off adjusting nut(don't unscrew) note how far the needle assembly is protruding above top of float body by counting threads. This will give a reference for reinstallation. Then replace adjusting nut, screw counterclokwise until needle and seat assem is free. Check if there is any crud holding needle open or damage to needle due to setting float too low. It doesn't take much to create a problem. Before reinstalling, I usually put a rag over the float bowl and start the fuel pump momentarily to blow out any other debris. Worth a try. Also check to see if float is still in good shape and, if brass, not leaking. Have a good pre carb filter? John Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted March 18, 2004 Author Share Posted March 18, 2004 Front barrels are primaries, rear barrels are secondaries. Thanks for the tips, as soon as my dad gets home I'll go through the needles etc. with him... I have a good filter but it's probably a good idea to check it around this point I think. Quote Link to comment Share on other sites More sharing options...
labrat Posted March 18, 2004 Share Posted March 18, 2004 Try tapping the carb near the needle adjustment with the handle of a screwdriver a few times. The couple of times this has happened to me, this cleared it up without disassembly. When the needle sticks open like this, a good tap usually clears it up quickly. Bill Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted March 18, 2004 Author Share Posted March 18, 2004 I did try tapping it before and didn't have any luck... Well, killed the battery and bungled the float measurement (got the screw and nut mixed up... as always) but I'm sure I'll get it going tomorrow morning. All I really needed to know was that the float/float needle were messed up as the symptoms were very strange and didn't correlate with anything I could think of. Well, this explanation works so I'm sure I'll get it sorted out. Thanks, everyone, for the advice Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 18, 2004 Share Posted March 18, 2004 I have had that exact problem (but with a POS 74 Impala) and it was debris on the needle valve preventing it from closing. The bowl simply overflows. The hammer fix didn't work for me, but I did find a bunch of crud in the bowl when I disassembled the carb. Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted March 18, 2004 Share Posted March 18, 2004 I'll add to the list of people saying it's crud on the needle. There's nothing worse than to be in traffic and the car dies and you hope you can roll into a parking spot!!! That's what happened to me and then opened the hood and find gas running down the carb. I then took the air cleaner off and just turned the key to run the fuel pump and gas shot up out of the carb. A small piece of crud was on the needle, that's all it took to cause my situation. LARRY Quote Link to comment Share on other sites More sharing options...
iaconsultants Posted March 18, 2004 Share Posted March 18, 2004 If you decide in the future to supercharge or Turbocharge your car with the Holley, drop me a line and I'll make sure you know how to set it up right, explain where to drill, and let you know how to make your secondaries work for your power range. I have done many Holley Carbs on turbo and supercharged cars. They are actually very good carbs. Have fun Robert Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted March 18, 2004 Author Share Posted March 18, 2004 Got 'er started, re-set the float level and all is well! Thanks very much for the fast responses and the accurate help, guys! Learn something new every day! Quote Link to comment Share on other sites More sharing options...
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