86'Bowtie

Ok,Ok
This has been a sought out problem repetitively on this board.
BUT, I need some helpful advice and info.

My carb recently has been running extremely rich. Smokes a little when started but after running it goes away but still is rich.
It's a Holley 750 double pumper. I've tried a few things and still can't resolve this problem. I adjusted the 4 corner screws 1 turn out from fully seated(any more and it smokes like crazy)Tried replacing power valve, wasn't the problem. What else could it be?

My spark plugs are fouled black w/ a charcoal sense residue.
And also my oil smells like fuel when I yank the breather off and smell inside the valve cover.I'm not losing water, just running rich.

Can someone please help me out. Thank you DUECE

dankhound

Make sure your float is set properly.

Also what kind of engine is this on. The double pumper is alot of carb and will run rich out of the box on a mild smallblock.

86'Bowtie

Float levels are perfect.
The motor is a 355 and yes it's a mild smallblock.
Any way to lean it out enough not to run too rich and smoke?

Also any solution as to why my oil smells like gas? Can this be bad, or caused by the richness? How can I solve this problem?

xpndbl3

iTrader: (5)

have you changed jets yet?

F-BIRD'88

Change the oil and filter. Oil is cheap, bearings are expensive. Change the spark plugs once a plug is Carbon fouled it will continue to misfire creating more carbon and fuel soaked oil.
Replace the metering block gaskets and put in a new power valve with gasket. Even a small pop or back fire can rupture the diaphram leaking fuel into the motor.
Make sure the PCV is hooked up and opterating. The carb is designed with it and will run exessivily rich at idle (fouling the plugs) without it.
Check the coil , cap rotor and wires. many "carb problems" are actually ignition problems.
What cam are u using? What intake manifold.

86'Bowtie

No, 72's primary, and I believe the secondaries are in the 80's
(possibly 84) or whatever the jets are for a 750 DP'er.

Would jetting down a size or two in the front help out alot?
Say 64 or so?

I'm running a Victor jr, w/ a mild cam close to 500 lift
I replaced the powervalve already and still runs rich.

dankhound

The fuel in the gas is most likely a by product of blowby. The rich condition doesnt help that any.

For the rich condition i would try lowering the float level some and see if that helps any.

Changing jets and powervalves can lean out parts of the rpm range but it sounds like your rich all the time. The only thing all of the circuits have in common is the float so id start from there.

86'Bowtie

By product of blow by?? Can you explain?
How can this be resolved?
Also, my valve cover breather tends to spit oil at times.
I have no baffle or grommet, can this be the reason?
PCV is perfect.

So, lowering jet sizes in the front won't help w/ richness.
Basically, I wanna lean it out as much to still put down the horses, yet stop the smoking from running TOO rich.

dankhound

Blowby is when combustion gas gets by the rings. It happens to the extream on new engines before the rings break in and old ones that have warn rings. Only real solution is to replace rings.

Jetting the carb smaller will help lean out the carb but only in the part throttle circuit. Youll still be rich at idle, off idle, and at wot.

1FastZ

also one good thing to check is to make sure your running the RIGHT power valve. Get yourself a vaccum gauge and check to see how much vaccum your engine is pulling at idle. Choose the power vavle that is closest to half of the vacucum pressure. Also do yourself a favor and get one of those Proform Main Bodies, they make one hell of a difference and they greatly help the holley.

86'Bowtie

Thanks for the replies, I'll check on that power valve, reason I put in the 6.5 is the carb already had a 6.5 PV in place.

I'll check the vaccum and go from there. What size jets would be a good recommendation for the primary swap?DUECE