Been tuning on my 650 demon for a while now and had it pretty good I thought, Been following demon tuning procedures to a T.Yesterday a friend who used to fool with Holleys quite a few years ago takes a look at it. He turns just 1 idle screw on the primary out another 1/2 turn and we take it for a ride. It was like I had just hooked nitrous to it. Astounding difference. Anyways, the manual says all screws should be turned out the same amount. With this imbalance now it works way better. We then tried the other primary screw and its about the same.
If we try and bring the secondary screws out the same amount it doesn't run near as good.Now this goes against everything I have read I think. With vacuum guage connected to it, vacuum drops when we turn it out to the new setting as opposed to where I had it. Does this make sense or is there reasoning behind this?

I should add I guess how the car ran. When I decided to change to vortec heads and had UDHarold recommend for me a cam the result I was after was a fairly quick nice car for sunday drives and cruises. I think I got more than I bargained for. My Beau now has some serious bite. Actually scared the crap out of me when we tested the carb tuning out. It just plain screams for lack of better terms. If floored from a dead stop it spins through 1st well into second and then chirps the tires when shifting. Its up to 5500 rpm at the blink of an eye.
Thanks for everyones help with getting me thru this

Instead of 1/2 turn on one side,,what about 1/4 turn on each side? I know in the old "how to hot rod big block chevys" book, they had a section on stagger jetting,seems big blocks with single plane manifolds like the stagger jetting a little better since cylinders tend to take the mixture from other cylinders,which doesnt have anything to do with idle mixture,but helps in the performance dept.

Sounds weird to me. If the idle mix screws being set richer caused more power, then you would probably be better off jetting richer instead then dropping the idle mix screws back down to where the should be (on the lean side of max vacuum).

Be careful -- seat-of-the-pants tuning can be misleading sometimes. It might feel faster, but you could actually have slowed down.

Thanks .No, this was definately more power, but I could try the jetting and see if I get similiar results.
Eric. 1 thing I noticed when tuning this carb before this weekend was I could open up the primary screws a bit more and rpm and vacuum would increase, but if I tried to put the secondary screws out to match the primaries vacuum and rpm would drop. I guess basically this is what he done. He opened the primaries more than the secondaries and it was a 100% improvement