Need Help adjusting carb

[Steven Harris]

Thanks gxr02190.

It has been a long time since I adjusted a Holley and do not have one handy to reference. I knew it would just be a matter of time for someone knowledgeable to come along and help us out.

PsychoThruster,

All the best as you tune in your ride. Enjoy.

[ylwhrse]

PshcoThruster, I would check for vaccume leaks as stated earlier.Before you get to far I would get a good handheld tach/dwell meter or just tach for testing. You can find them inexpensive at oreilly or any good autoparts store. You can also check for vaccum leaks at the vaccum hose conections with carb cleaner sprayed around them as well or a little safer to use is a good old fashioned propane torch unlit and barely open the valve and run the propane at the suspected points.If you use propane be sure none gets sucked in the mouth of carb or you will get a false reading. Any change in RPM's up or down indicate a leak at that point. I would also spray along each side of the intake manifold were it meats the head, a fairly commom place for clevelands to leak. Next I would pull the site screws on float bowls and verify the fuel level is correct. You should be able to take them out and fuel should be at just the bottom of the hole and at most barely dribble out (BARELY ) I prefer to set mine just so it does not come out of the hole and thats even on my 725 horsepower stroked cleveland. Next i cant tell what kind of carb it is, if its a holley depending on size, there will be two idle mixture screws on the front metering blocks and maybe two on the secondary metering block. The metering block is the piece of metal between the carb body and the float bowl. The idle mixture screw will be on each side of the block. A good place to start would be 1-1/2 to 2 turns out each. Remember to keep them even. Now the fun part, with the car warm and please do all tests / adjustments with the car warm, hook up your tach and slowly turn the screws in (tighter ) by say 1/4 turn watching your tach. If the idle drops move back to starting postion and try 1/4 turn out.Hopefully you will see a idle increase turning the screw one way or the other. Do 1 screw at a time till you achieve best idle then move on to the next, going round and round until you reach the smoothest best idle. At some point your idle may be to high and your carb will overide the idle circuit and you may have to adjust the curb idle down. the curb idle is a larger screw typically in the baseplate next to were your throttle cable is attached. Tightening the screw typically increases idle while loosening it decreases the idle. Depending on camshaft your engine should idle in neutrol somewere around 650-700 RPMs and if automatic in gear 550-650 RPM's however camshafts can and do effect idle. My stroker motor with a solid roller cam idles at 1050 RPM's. So all is relevant. Before making ANY carb adjustments find and fix your vaccum leaks first. Lastly check your ignition timing. Depending on were you live it should be from 8 to 10 degrees BTDC. But even stock clevelands like timing so dont be afraid of 10 to 12 degrees as long as you get no pinging.
Hope this helps if you have any other questions please msg me.
YLWHRSE

[Oztrailer]

I have just recently had problems with my car running really rough at idle and feels like missing on accelerating when cold. Have adjusted dwell (points), plugs, timing .........all spot on where it should be. Adjusted the idle screws on the Holley, still couldn't get it to run right. Last night noticed on the inlet manifold a spot on each side where it looks like the gasket has slipped out. Could hear it sucking air there and plugged with my finger ... ouch, hot : ) ....and noticed the revs drop off. So this morning used some engine silastic and stuck some on each spot to seal it. Will give it a run tomorrow after the gasket stuff sets to see how it goes now. I suspect I may have to adjust the carb again now that the air leaks are sealed.

Would running with air leaks on the inlet manifold have leaned it out to much? Hope I haven't burnt any valves.

[gxr02190]

Vacuum leaks will definately cause a lean-out condition.