ok guys, i dont know jack about carbs. and im having a heck of a time here. im working on a truck for a guy, its got a buick v6 with a holley 4 bbl on it. when he gets down on it, its pumping black smoke. means its running rich right? i adjusted the idle mixture screws all the way in, and all the way out, and does make much difference. what do i need to do to get it right? id appreciate any help. thanks guys trey
1) Remove holley 4bbl 2) Discard 3) Purchase and install edlebrock (afb) carb 4) drive it and forget it. Done!
Most Holley 4 barrels work best at 1 and 1/2 turns out....or so. I always base line mine there. With a vacuum gauge..........I adjust the screw in and out to find the highest reading....back off slightly. Repeat on the other side. I do this a time or two until I am satisfied. The jets may be too large for the V6. Changing them is very simple.
do i just pull the float bowl off to change the jets? or do i have to pull the block behind that off too? the jets are in the one facing the front, right? man, im a carb idiot. trey
[ QUOTE ] sounds like a blown power valve to me.or do what burndup said. [/ QUOTE ] <font color="black"> Yeah...they are cheap and easy to change........I would try that too.... </font>
Go to the holley web site. They have a bunch of good info on there. Its really easy to change jets and power valves on holleys. Both are located behind the front bowl. 4 bolts. Remove one of the lower ones first. You will have a bunch of gas come out of it (everything thats in the bowl) so be ready with something to catch it with something. The jets will be on the front of the metering block, the powervalve on the back.
It may be too much accelerator pump also ,does it just black smoke for a couple seconds or for all the time your jumping on it?
ok, i ****ed with this stupid thing some more today. checked the power valve, looked fine. jets were #99's. went down to 64, its still bellowing smoke under load. the next size down i have is 49, should i keep going down? i looked around on the holley site, didnt find much of what i needed. thanks guys trey
hahaha,you can't just look at a power valve to see if it's bad or not.now go change that ****er like we told you to!
Get a rebuild kit for it. Go through it & clean it really well. Pay close attention to the idle air bleeds (little br*** jet-looking things facing up on the top of the carb just inside the air cleaner base at each end near the booster venturis). Run some good carb cleaner through each & every orifice (wear goggles!) If it's never been apart - take your time to get all the factory gaskets off the bowl & metering block - a good overnight soaking in any type of solvent will help. Check your jets - as a WAG for a V6, I'd ballpark you somewhere between 58-62 without knowing anything else. I'd ballpark your powervalve at 8.5 - replace it & put in a powervalve check valve avail from about a zillion places like Summit & Jegs for about $3. Set the initial float height by putting the bowl upside-down & making the top of the float (now at the bottom) level with the top of the bowl (also at the bottom). Put it back together. See where you're at. When you get it so it isn't blowing black smoke all the time, let us know & we'll get you closer. Ryan won't like this, but search the archives - lots of good info on Holleys here. They aren't any better or worse than the Carter/Weber/Edelebrock - but lots of folks seem to favor one over the other - I prefer the Holley because I personally find them easier to tune & work on (and parts are easier to find/cheaper). Good Luck!
What size carb is it? It may just be the wrong carb for that motor. When you say it has black smoke under load, is that when the 4 barrel is open? If it isn't a 390cfm, I'd take it off and replace it with a 350, or 500cfm two barrel.
check the float level,you can do this easily with the car running.There are sight screws on the side of the carb ,take these out and there should be no fuel coming out of them as the level is up to the bottom of the screw hole.If fuel is poring out adjust level to the bottom of the hole and it should work.Also you may need to check the fuel pressure as holly's are real sensitive to it apparently...........Marq
Yeah change the power valve. You can't look at it and tell if its ok. You wanna learn more than you need check out http://www.bob2000.com/carb.htm 99 on the jet was WAY too big. 62s may even be to big, but its a better place to be around. http://www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html has good info on the different parts of the carb.
The Jalopy Journal
