Just for grins, check them throttle butterfly screws. Sounds like a hidden overlooked problem. If nothing else, you don't need them going into the motor. Do you have a vacuum tree at the back of the intake? Your manifolds gettin hotter than normal? Mine did and it was the idle screws had backed out cause the cork "o" rings rotted.
Had the same problem with my Demon carb when I first put it on. Turned out the idle circuits were way too lean. installed some restrictors in the air bleeds and fix the problem. Dont know if Holley uses them or not.
I had the same problem with a Firebird when I was a young'un ... brand new carb. Turned out that the choke interfered a bit with the EGR valve and was holding the carb up off the manifold 1/16th of an inch. Took me too long to figure that one out ...
All great ideas thanks! This Holley I bought new about 18 years ago, it hasn't seen much use, and it was fine last time I used it, so I'll go buy a kit for it today, and see how it works after.
Did you start it with the throttle linkage unhooked off the side of the carb? My car idled high, I had to bend the throttle bracket frt a little then it idled fine.
If this is a vacuum secondary Holley and it has been sitting you should check the secondaries for complete closure. You might have to replace the secondary diaphagm. If it is manual secondary carb then check to be sure that the secondary throttle stop screw is letting the rear throttle plates close completely without binding. If the secondaries are ope even a little bit you can run a lot of air through then at an idle.
There's your problem. It's more'n likely got the old cork bowl and metering block gaskets. Once they dry out, they shrink up and make the carb totally useless as far as bolting it back on and reusing it without a rebuild first.
I pulled them off last night, they weren't cork, but I figured I do a rebuild anyways, the kits are cheap, I grabbed one today.
Have you ever built a Holley? Just curious. I like to preach to folks that haven't, that they should get one of the many books on the subject and read voraciously. If you have, then nevermind. Just want to help. Dave
Both Edlebrock and Holley have their pros and cons. I enjoyed my edelbrock, but each time I modified my engine, I had to recalibrate it to run a little richer. It finally got to the point where 600 cfm just didn't have the calibration needles and jets to keep feeding my engine enough. Then I acquired a VERY used double pumper Holley, and got to start all over again. The holley initially "feels like" working with a dinosaur compared to the holley. You have to completely disassemble it to swap out jets and stuff, and there are moving parts on the outside which is kinda disturbing at first. But once you tear it down a couple times and buy all the jets, it takes just a few minutes to swap them out. Just gotta learn to catch the bowl-full of fuel as you take it down. All in all, I loved my Edelbrock, but if I did it again, I would go 750. I am learning to love my Holley... All in all, I strongly encourage borrowing a buddy's carb and trying it out for size.
Catching the fuel from the bowls is easy. Cut the bottom third off a 20 oz plastic coke bottle and use it to catch the fuel as you remove one bottom bowl screw.
