My chevy 350 is running rich,black smoke,burning eyes the hole 9 yards. the 4bbl. holley is a dual feed 650,it has 4 screws total on the metering plates.do you guys remember which way i turn the screws? I think it's out 2 1/2 turns after the engine is completly warmed up.i didn't have this problem till i switched intake and carb set up.thanks guys JJ
ouch! my eyes are burning
- Thread starter jjsticks
- Start date
Sounds like it could be a blown power valve. Screw the mixture screws all the way in with the engine running. The engine should die. If not you have internal carb problems. Blown power valve, float level wrong, stuck needle and seat, or even a bad float. Also with the air filter off and the engine running, do you see any fuel going into the carb, down the barrells? There should not be, any visable fuel at idle.
one finger john
Active Member
The idle adjusters for Holleys have been known to lean out or richen up the idle mixture, depending on the carb and year manufactured. I believe turning the idle screws in leans them out most of the time. Screwing them out richens them. Set the throttle plates at just a hair open (approx. .010), screw the adjusters in until the car dies, then slowly screw them out 1/4 turn at a time until the idle is at its highest rpm. Vacuum should also be at its highest. Then go back to the throttle plates and readjust for idle speed. Start with the idle adjusters 3/4 of a turn out. Turn them in til it dies, then out til its smooth.
If the carb has been modified, buy a book, set everything to stock and follow their instructions to set idle.
Un-known modifications are the bane of all carb tuning problems.
John
If the carb has been modified, buy a book, set everything to stock and follow their instructions to set idle.
Un-known modifications are the bane of all carb tuning problems.
John
Screaming Metal
Active Member
RPM said:
Yep, what he said..............Also try what that other dude told ya. If that fails......take your air cleaner off.....look into your airhorn your gonna see 4 sets of really small air bleed holes......with your engine idling......either use your fingers or you can use toothpicks....but be careful not to drop them onto your carb or break them off into the bleeds.
What you want to do is block off the 2 inner holes closest to your vent tube. If you block these off and your car smooths out......its your power valve circuit.
You gotta lot of carb on that engine........gotta single plane, Cam and headers??????
If all else fails.....do one thing at a time:
1. Set your floats.
2. If your running a HiPerf fuel pump, set your regulator at 4 to 7 psi......no more. Look into your carb throat if you've got electric pump....if you see fuel....you seats are leaking.
3. Idle your car to 750 rpm......crack the throttle fast....if its good and chrisp......your low to mid is OK, if it stumbles.....either the accl. pump is at fault mid's too rich......check your jets. If your running a whole LOTTA cam......Idle it to 1000 and try it.
If the carb was fine on your engine and all of a sudden started this....check your fuel filter....you might have sucked up some trash. Make sure your not flooding, ie, float too high.........might simply try a good strong card cleaner and wash the crap outta it.
I could be something as simple as your carb is fine and your losing spark......I had this happen to a new Mallory no too long ago.
Take your time and go one step at a time....these things can be very frustrating at times..................................
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