Just got through installing my new carb (bought used). It appears to be in good shape with the only mods being to drill a small hole in each throttle plate for better idle. My current carb also had the same holes.

It's a Holley 950HP dp. replaced the 750 annular booster dp on my 383W drag car. I know that's alot of carb for a 383, but I have seen other guys use them with success. Also, with my converter and shift points the whole rpm range is from 5400-7000.

Bolted on, set the floats. Idles decent for a solid roller (1100, would idle at 900-950 with 750).

Problem is when I blip the gas. If I run the rpms over 4K and let off the idle only drops to 3K. Throttle is not hung open, no gas coming from the boosters, so I don't think it's running on the mains.

At first I thought it might be the power valve. Started out with a 6.5 pv up front, 75 jets front, 81 jets and pv plug in the secondary. Changed it to 81 square with pv plugs front and rear. No difference.

Maybe gas just puddled under the carb? I know it puts plenty in there. Those drop leg boosters look like Niagra falls when the throttle is open.

Ideas??

Thanks,

Could the secondary butterfly be hanging up slightly? Maybe when you blip'd it to 4,000 you opened the secondaries slightly. The puddled gas shouldn't do it 'cause it still needs enough air to idle at 3,000.

The secondaries were hanging open. Not catching on anything. I pulled it off and checked to make sure it wasn't hitting the gasket or spacer.

Turns out the spring on the secondary throttle shaft was very weak. When I blipped it far enough to open the secondaries the spring couldn't close it past the airflow. That's why I could shut it off, refire instantly and the idle was normal. With no airflow the spring could close it.

The spring is a coil that wraps around the shaft on the drivers side. I cured the problem by taking it off by hand (it was that weak) and wrapping it one more turn around the shaft.

Th spring is fairly tight now. Anyone ever run into this problem before? Will it hurt the spring to have it tighter? Any possiblility of breaking it?

BTW, it idles better now also. 1000 rpm in park. Haven't tried it yet in gear.

Later,

Not yet. It rained here the Fri night. And then I had to work Sat and Sun.

Lot's of overtime right now. I'm a railroad freight conductor. Lot's of security measures going on due to being a possible terrorist target when at work. Slows things down when running trains. Means overtime.

Working for a railroad right now makes me feel like I've got a big bullseye target on my back. You hold your breath when crossings bridges etc.

Later,

The 950 HP was worth .10, .05 of that was in the 60 ft. It will have more in it once I get a chance to tune on it. Prob .20 overall.

Only made three passes, the first was lean at 81 square jetting (pv's plugged), it was popping during the burnout and at the top of first gear. Jetted it up to 85 sqaure and the popping was gone, best run. 3rd run raaised the launch rpm and spun, but think it was dure to water brought to the line by the A**hole ricer in front of me. Car went about 6 inches and then I was pointed towards the wall.

Cooled off, was going to make another, but the starter had come loose, top bolt was gone, hanging by the bottom bolt. The bottom bolt pulled the threads out of the bellhousing. By the time I found a bolt and got it fixed the track was closing.

BTW, my old carb is now for sale in the classified forum.

Later,

David Cole