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View Full Version : How to adjust my Demon carb



Moabdude
12-26-2007, 02:39 PM
My 69 Nova has a demon carb. it runs about 1200RPM at idle. There are 4 screws, 2 on each side. Which one do I need to set the RPM to about 900?

John McIntire
12-26-2007, 04:27 PM
you shouldnt have to touch those. Theres a screw on the throttle linkage that you can slowly back out to bring down the RPM. Look around where your throttle cable hooks up to your carb linkage

MonzaRacer
12-31-2007, 03:12 PM
Well first you need a vacuum guage hooked to manifold vacuum to do it right. if its an auto trans let it idle against a wheel chock or have someone hold the brake while you adjust.
Idle it down to around a 1000, then run each of the side screws in till you see the vacuum guage needle drop towards zero then backj it out till the vacuum goes backup. Then reset your idle speed and then try to maximise the mixture screws again till your satisfied its smooth and stable.
The big problem with just idling it back down is it may be int ot he idle transition slots.
Good Luck.

jvest
01-01-2008, 12:55 PM
Well first you need a vacuum guage hooked to manifold vacuum to do it right. if its an auto trans let it idle against a wheel chock or have someone hold the brake while you adjust.
Idle it down to around a 1000, then run each of the side screws in till you see the vacuum guage needle drop towards zero then backj it out till the vacuum goes backup. Then reset your idle speed and then try to maximise the mixture screws again till your satisfied its smooth and stable.
The big problem with just idling it back down is it may be int ot he idle transition slots.
Good Luck.

MonzaRacer is correct on setting the four idle mixer screws. Make sure you set the throttle plate screws as instructed in the manual, so you get the butterflies postioned correctly on the transition slots. You'll want to use the ez-idle screw under the air cleaner stud to set your idle speed. The older tappered ez-idle screw will take more turns out from bottom than the newer blount point ez-idle screws. I've got the older style and it's around 5 rounds out.

Hope this helps,
Jim