OK, I just got my car running again after having most of it apart. The only thing that I did to the engine was rebuild the carb (4011 Holley spread bore 650 DP) It was pretty dirty inside. The last time that I had it running I noticed that when turning the idle mixture screws it did not affect how the car ran. I knew it needed a rebuild because of the old gas from the last 12 years. I bought a Holley rebuild kit and rebuilt the whole carb, mind you it's an old carb but has very low miles on it. I got the car running adjusted the floats, those clear sight plus are great and then went to adjust the idle mixture screws no go again. I have the car idling at about 800 rpm's if my stock tach is correct but it will not stay running at a lower rpm. Is it possible that I am out of my idle circuit and any adjustments are not going to make a difference. The car runs and sounds great. It has around 3-4 inches of vacuum at idle. It has always been like this so I do not think there are any other problems. If you need cam specs I can post them also.

Thanks in advance for any help.

How big is the cam? How much initial timing are you running? Is it running on all 8 cylinders & have you verified this?

I pull about 14" of vacuum at idle & idle my car around 1000rpm.

Initial timing will play a major roll in how well the car idles

-Carm

Vacuum leak?

The car has a Ultradyne cam 288/296 lobe sep 108, gross valve lift Intake 485 and Exhaust 507 duration at .050 231/239 I will have to check my initial timing but it should be at 12. I had good vacuum and I could adjust the idle mixture screws when I had Rhoades lifters in on the same cam. I just could not stand the ticking noise that they made. I had the dizzt recurved eons ago and they told me to block off the vacuum advance.

Cam is pretty big but 3-4" doesn't sound right. Does the Rhodes lifters actually add that much vacuum?

If the idle screw won't work then you probably have the blades cracked open enough to be out of the idle circuit.

If nothing has changed except for the lifters(and they aren't the cause) and the carb then I'm thinking retarded timing (too little initial, the timing chain jumped/really worn) or possible vacuum leak.

First a bunch of questions..... is the 12 year old gas out of there, do you have a GOOD fuel filter keeping the rusty crap from the tank out of the carb, and what is the list # and what size jets do you have in it.

Get the carb back to stock calibration (Holley has a list of factory calibrations on thsie web site) Unless your elevation is way up there 5000+, just start with the stock, factory jetting and all and see if things don't get better. Borrow a vacuum gauge and see how much vacuum you have at idle (whatever that may be). That cam is not that big, you should have around 9-10ish inches of idle vacuum would be my guess. But let's get back to a stock carb calibration, and see what you have.

Thanks for the replys so far. I drained all of the old gas out and put in all new lines including the hards and a new fuel filter. The carb is bone stock and has the original jets are still in it. Elevation should not be a problem since I live in Minnesota. When idling the car runs great and has a very snappy response when giving it gas. I will check the timing again this evening.

MORE I did notice after lowering the idle down more that I could get the idle to change when screwing the drivers side idle screw all the way in the passenger side idle mix screw dosn't seem to change much of anything. I was also wondering if I'm pulling vacuum from the right source. I have my guage hooked up the carb where the port is even with the throttle blade shafts. Should I be pulling vacuum off of the intake for a better reading?

Alright I changed where I pull my vacuum from. I pulled the line going to the power booster and plugged in my guage and had around 8 inches of vacuum. I plan on changing all of the plugs and the oil next week, I hope this will help some. If not I will try adjusting the valves again making sure they are not to tight. I checked the timing and it's set right at 12 degrees.