81 Holley Carb Over-idle Problem

[Steve P]

My street/strip cammed 350 is equiped with the stock Holley w/ electric choke. All polution crap is removed and several ports(all except EGR I think) in the carb are blocked with a short hose and bolt. It is over-reving at idle after completely warming up. I set the idle at around 800 while warm then go out for a short test drive. After getting on it a little, (not much over 3000 rpm) it gets stuck in something like fast idle mode(like 2000 rpm). I can turn the idle screw down to 800 again but when I restart it later the idle is so low it won't run. I have cleaned and lubricated the linkages and checked for a sticky acelerator pump. There is power to the choke when the key is on. Everything seems to be moving freely. I'm no carb genius. Seems like the prob is in the choke system or something to do with that rod that contlols the cam under the idle set screw. I'm in Canada but don't plan to run the car in winter so the choke is not really a major concern. Can it be easily removed from the equation.

Don't know if a power valve could cause this problem?

Any help welcome

Thx, Steve

 

[JohnZ]

81's didn't have Holleys, so I assume the carb and intake manifold have been changed. Sounds like the fast idle cam isn't dropping out, or the choke housing needs to be adjusted. Also, the hot lead to the electric choke should have a full 12-volt feed - it needs a full 12 volts to operate properly.

 

[lnirenberg]

I just went through a similar problem where the idle got higher as the car warmed up, my problem was going from the 700 at start to 1000 rpms not quite in your league. I can't imagine that it has anything to do with the choke as even Ottawa gets hot in the summer. If you take off the air cleaner before you do a cold start you can watch the choke and my guess is you will find it wide open. If not that could be 1 off your problems, except that for me with the choke engaged the revs go up. I wouldn't remove the choke because when I got mine from Florida I had cold idle problems on cool summer mornings and when I took off the air cleaner lo and behold the choke had been removed from the aftermarket Holley. I don't drive once the snow falls but there are plenty of days the choke is very useful even up north. I solved my idle problem by fixing a vacuum leak and connecting the vacuum advance hose to what someone here called the ported vacuum nipple on the carb (part time vacuum, not at idle). Runs great now. I second John Z on the idle cam issue. If you don't have the manual that came with the carb, go on line and find it. Try Holley product support, as I run an edelbrock and their product support was very helpful in the troubleshooting area, all by email.

 

[AUSSIEVETTEMAN]

Dudes......

Typical damn Holley!
I have a mate with a holley carb on his 'rustang' and he has to drive it around the block a couple of times before it gets warm and will run right.

When we got our 81, the previous owner installed a Holley 650 cfm carb on the old girl. First thing we did was purchase an Edelbrock Qjet 795cfm carb. She came alive again with the extra airflow. I used the holley as a boat anchor!
Best move putting the Qjet on.



Tony

 

[ON 7TH]

If its a holly spread boar replacemrnt with vacume secondaries it should idle at 750 ,if ya crank up the idle the secondary plates will also have to be adjusted. .