High idle; can't get it down

[mrk5]

High idle; can\'t get it down

I just got my engine running after having it rebuilt. I'm using a Road Demon 625, MSD Distributor, and performer intake.

Here's my problem, the idle is at about 1100rpm in park. The idle speed screw is as far out as it will go and still contact the throttle lever. Timing set at 8btdc. Choke is wide open.

I can get the idle down by taking the timing down to 0.

Is this a vacuum leak or what? Or I'm wondering if it has anything to do with the idle mixture.

Any ideas.

 

[pauly383]

Re: High idle; can\'t get it down

Engine RPM will not come down :


A) Increase initial timing. The engine's initial timing should be between 18 and 24 BTDC (before Top Dead Center). Use a timing light. Try this next if this didn't solve the problem B) Readjust butterfly position, both primary & secondary. With the engine off, disconnect the fuel line and them remove the carburetor from the intake manifold. Drain the fuel from the float bowls. Turn the carburetor upside down on and place on a carburetor service stand (such as BG Fuel Systems 130002). Check the transfer slot openings, which should show 0.020" of the transfer slot exposed (it should be a square opening). If not, use a straight blade screwdriver, and turn the throttle adjustment screw on both shafts until the butterflies exposes 0.020" of the transfer slots in all four throttle bores. Try this next if this didn't solve the problem

Road Demon troubleshooting

 

[mrk5]

Re: High idle; can\'t get it down

18-24 /forums/images/graemlins/yikes.gif

That just seems like an insane amount of advance.

I did all the other steps before installing it on the truck.

 

[pauly383]

Re: High idle; can\'t get it down

Does seem high, would make mine ping I'm sure. /forums/images/graemlins/k5.gif

 

[mrk5]

Re: High idle; can\'t get it down

I always say it's best to learn from other's mistakes, so here goes.

It was a vacuum leak, a massive one. Instead of torquing the carb mounting nuts to 8 ft-lbs, I did 8 in-lbs! /forums/images/graemlins/doah.gif

Fixed that, returned everything to factory settings, and what do you know; it ran great! /forums/images/graemlins/woot.gif /forums/images/graemlins/whistling.gif /forums/images/graemlins/rolleyes.gif