need carb help badly

[HP400RW]

I need your help badly. my friend just droped a 351c in his car and got a new edelbrock 600cfm carb and we are having major problem. Eveything is hooked up and connected but when we goto start the car it starts up and immediatly winds up to 4000 rpm. we know its not good or safe for the motor and we think it has something to do with the carb but it could be something else, thats where you guys come in. Does anyone know why it winds up to 4000rpm right away and do you know how to fix it? i would greatly appreciate any advice.

Thanks a lot

[matt1190]

If you have a vac advance distributor, it's possible that you could've put the hose to the wrong port on the carb. Did you properly set the idle mix screws? check float levels? Kind of an odd problem for a new carb though...

[Lou Lyman]

Is your accelerator linkage/cable adjusted to permit the throttle shaft to rotate to the idle position?

[66StangGuy]

i had the same issue with my holley 600 cfm vac. secondary. heres what happned to me

first the idle speed screw was too high.

i asjusted that so it bairly opned the primary throttle.

then found that the secondaries were sticking open. there is a screw in the back of the carb on the passengers side that adjusts the throttle plates for the secondaries.

then check your float level front and back.

also check the hose that runs from the vaccume source to the secondaries diaphram and spring. there shound be a black hose on the passenger side of the car.

also unplug and cap all vaccume ports to iscolate the problem.
vaccume advance and trans vaccume is not important for idle.

[HP400RW]

thank you all so much were are gonna try everything this weekend.

[429mustang]

I have an edelbrock 600, it's a POS. I can't get it to run good for more than a few days, when I take it apart to set the floats and put it back together it runs real good for a few days, then starts running real rich all the time until I take it apart again. Any ideas?

[Jeff65]

Originally posted by 429mustang
I have an edelbrock 600, it's a POS. I can't get it to run good for more than a few days, when I take it apart to set the floats and put it back together it runs real good for a few days, then starts running real rich all the time until I take it apart again. Any ideas?

Check your fuel pump pressure. Do you have an electric or high capacity mechanical pump? Seems like pressure's too high. If too high, your carb floats can't shut flow off correctly.

[MCINTHEODC]

yah... mine is almost like that too... IVE GOT A 302 W/ HOLLY 650 DP
when its in park it idles about 2500... when in gear it drops to about 600...it runs fine( never dies , always starts up right away)
Ive tried everything i can think of.... Maybe too big of carb?

[429mustang]

It seems like it cold be from excessive fuel pressure, but I'm using an edelbrock performer pump recommended for the rest of the edelbrock setup I'm running (rpm cam/carb/intake). The pump is supposed to be set at 6 psi max, and the recomended psi is around 5.5, although I don't understand how that little of a difference in pressure would make it run crappy, especially just idling when the pressure isn't that high anyway. Last friday it stopped bogging out and loading up, it's run ok for a week but it's still rich. If anyone wants to buy a 600 carb let me know.

[Dark Knight]

MCINTHEODC, you probably have a pretty big vacum leak..try covering the carb with your hands when it's running.. if it dies, it's something else..if it doesnt, it has a leak..

high fuel pressure wont cause it to idle fast.. it will kill it when it floods it...
check for dirt in the carb... might have got something in the fuel line that worked it's way into the carb when you put it on...

[66StangGuy]

if you cover the carb then it will die no matter what. if you cover the carb then you cut off the engines fuel. no vaccume through the carb will not allow the system to work to give the motor fuel.

im sure of your problem like i posted because i had the same issue. im almost posative the that secondaries are sticking open and giving the motor too much air\fuel then what you want.

back off the idle screw on the drivers side all the way out so the front throttle plates are closed. then start the car and see if it does the same thing. if it does then the secondaries are open.

if you try this and it works post your reply and i will help you with closing the secondaries.