my car is running horrible, first, some backround. it was a 305 tbi 1988 trans am. i swapped in a gm 350 h.o. crate engine. holly 650 dp carb. timing is at 16 btdc. i have 4000 mi on the combo, all parts were new and ran fine before today. i drove to work today fine until i stopped at a stop light, and the engine quit. i started it and i would have to keep the rpms high or it would die. now im done with work and need to get home. i can get it to run but it just runs bad, its a little shaky. if i rev it it sputters. i pulled a spark plug and it a powdery black(could it be because of me reving it). timing hasnt changed. yesterday i was messing with the carb trying to lower the idle, maybe i was turning the wrong screw, idk. can u help at all. i need to get home
thanks

 

well if all your plugs are like that, then you probably fouled them up. Might need to pull them and clean em off with a brush or sand paper. Even if you get the carb running right, if the plugs are fouled it won't burn the fuel in the cylinders. Holleys are finicky when it comes to setting the idle right. The throttle plates need to be close to shut with only a small amount of the transfer slots showing. If you adjust the mixture screws and it has no effect on idle then you have the throttle plate to far open at idle.

Also is your choke operating correctly if you have one.

 

Sounds like the carb is flooding.

Remove the carb needles and seats assemblies and blow/wash them out.
reinstall them and reset the float level.
(screw driver and 5/8" wrench)

The plugs are fouled now and will need to be replaced.
Cleaning off the carbon will only help temperairly.
get new ones.

Get a good inline fuel filter to avoid the flooding problems.

 

all the plugs are firing because all the primaries are getting hot (could it still be plugs). i dont know where the mixture screw is, only the idle screws and fast idel screw. i also have a manal choke which is not on.

 

just take out the screws that u use to set the float level? blow them off, and put them back in. also, yesterday, i was fixing a leaky fuel line and it is possible that a piece of teflon tape got through. thansk for all the help guys

 

here's what each "screw" does on a holley

 

how do i get to the carb needles and seats assemblies

 

You have to unscrew the lock screw, turn out the adjusting nut till the needle and seat comes up and out. Remove it and clean it.

reinstall it and adjust the fuel height till the fuel just comes up to the site plug hole.

Teflon tape will do that. use the liquid. Get a fuel filter.

Look down the carb inlet while running to see which side is flooding ( primary or sec side) fix that one.

Watch your hair. LOL

 

ill try that, right now im pulling the plugs and cleaning them. do u know if it is 2.5 turns out for the idle adjustment(factory). also, what would i be looking for when looking into the carb?

 

ok, well, im home now. i couldnt take my car. either im gonna have to clean it out or have someone do it. def. dont know how to do it, ill run a search.

 

no clue, am i going ot need a rebuild kit? what will i need to do, just blow out all the jets? there has to be teflon tape somewhere in there

 

The jets rarely ever get clogged on a holley. (unless you feed it teflon tape) But if that will make ya feel better, go for it.
You won't need a rebuild kit unless you tear a gasket.
I suggest you get a book on servicing Holley carbs.

One of the haynes series or HP series books are good.
Many well stock performance oriented auto parts stores stock them. You can order them online at amazon too.

http://www.amazon.com/exec/obidos/tg...glance&s=books

and or http://www.amazon.com/exec/obidos/tg...glance&s=books

There is no fixed base setting for the idle mixture screws.
1.5 to 2 turns out usually is good enough to start the car.

let the motor fully warm up to operation temp.
Adjust the idle mixture screws (could be 2 or 4 screws) slowly to achieve the best idle manifold vacuum and speed. Then reset the idle speed screw to set the idle speed.

Fix the flooding condition first and replace the spark plugs.
Do you have a inline fuel filter in the fuel line before the carb?

Best $13 you'll spend on your carb.

 

The best thing you can do is $hit can the holley!!!!!!!!!!

its a great carb. when it works right,but it is really touchy....
My experiance with holleys is this...for track,drags racing,etc. holley works tit,but everyday driving sucks! I know theres alot of people that disagree,but after you have messed with them over and over you'll begin to hate them too, or when the floats stick open and gas your motor up...I went to the edelbrock
on my other Z-28 I took it apart as soon as it came out out of the box ,set the floats (because factory settings are off) bought the needles and spring kit to get it where I wanted ,and never had a problem with it what so ever,
and that motor had just a hair under 400HP and it went nice.

either way good luck,let us know when you get it all running

 

I'm suprised you haven't gotten flamed for that by now. But I have to agree with you on that point. They are touchy. I have learned from making several trips an hour away to help a friend out with his. Holleys are a good carb for somebody that is good a trouble shooting and doesn't mind learning a little about their carb. You can crank the idle up and down all day long on a q-jet and not worry about it. On a holley you end up loading the motor up with fuel and fouling a bunch of plugs just by having the throttle plates to far open at idle.

But I aslo think they are easier to troubleshoot and work on. Just not a good carb for someone to bolt on and go, like they advertise.

 

exactly! theres not much to em...and if they ever need rebuilding
its a snap. They do have newer type Holleys that are better than they used to be,Jegs, Summit selles them,its all personal preferance

 

ok, well, i took off the carb, took off the fuel bowls and blew everything i could with compressed air. put it back together and it worked...that is till the radiator blew at 220 degrees. at least this time i had a ride home. just picked up a new radiator for 150 and im gonna put it in tomorrow. thanks everyone for your help.

im ideling at 1000 right now, do i mess with the idle mixture screws (factory 1.5 turns) or the throttle plates?

 

both.........

Work each idle mix screw to get the best lean idle.
(there are either 2 or 4 diel mix screws) repeat all till you get the best lean idle.
leaner is clockwise, richer is counterclockwise.
Turn each screw in till the motor slows then turn it out till the motor just recovers. Go the the next/ other screw and repeat.
Work slowly, let the motor react the the fuel change.

then adjust the idle rpm withe the idle speed screw.
the motor will want more fuel when cold than when hot.
Set it up hot. hook up the choke for cold weather operation and starting.
then repeat the idle mixture screw setting.