holley carb idle problem

[48chebbie]

hi folks. i have run into a snag. i just put a new 600 holley carb on the 318 in my 74 roadrunner and i have run into an issue that baffles me. the carb will not idle down to anything less than about 1000 rpm. the motor has an edelbrock sp2p 318 intake on it and i added this brand new out of the box 600 holley to it. the idle screw on the side is completely backed off,the timing is set at 10 degrees initial,and to get it to idle down,i have to have the mixture screws on the metering plate jacked so far in,that the car runs terrible. you can actually grab the throttle arm and physically pull it forward and it will idle down,but it takes more force than the return springs can provide. and i have double springs on it now. there are no vacuum leaks anywhere,and i have checked everything. throttle liinkage has plenty of slack and the detent slide is not binding. even took the carb off,took it back and got another new one. car runs great otherwise. any help would be appreciated.

[charger_fan_4ever]

I experienced a hanging idle around 1,100 with a holley 750. Had to yank it to get it back down. I went to 2 heavy return springs and it cured it.

Do you have a pic of how the return springs are mounted? Some times the return spring needs to be mounted directly in front of an intake bolt to get more leverage.

[firefighter3931]

You have something binding up....check the carb base gasket and linkage/throttle shafts. 


Ron

[48chebbie]

i have 2 springs on the return. they are mounted to the stock spring bracket. they are stiff enuff that pressing the gas pedal for long periods of time is a chore. i have not tried the trick of loosening the blades screws, slapping the throttle shut and re tightening them but that is next on the list. car runs great otherwise, drove it to the NATS the other weekend,which was a 1000 mile round trip.

[48chebbie]

got it fixed. loosened the blades,adjusted them slightly,which allowed the blades to close all the way. now have idle screw adjustment and now she idles smooth as a mothers love. thanks for the input.

[Rolling_Thunder]

had this problem with a demon once...    same thing fixed it....     

[firefighter3931]

got it fixed. loosened the blades,adjusted them slightly,which allowed the blades to close all the way. now have idle screw adjustment and now she idles smooth as a mothers love. thanks for the input.

Nice work ! 



Ron