Carbed LS1 guys please HELP

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Nov 17, 2006 | 02:02 PM

caged02

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From: Altoona, Iowa

Carbed LS1 guys please HELP

I am having a hard time getting my LS1 to idle right. I am running a 232/236 .595/.601 lift cam with a Victor Jr. intake and a 750 mechanical secondary Speed Demon carb with a auto. I am running the #6 chip in the box for the timing. It either idles to high (1200 rpm) or if we get it anything under that the idle is kind of all over the place. It almost sounds like a timing issue rather than dialing the carb in? Please help if anybody else has this same kind of set up or have experienced this problem.
Thank you,
Scott

Nov 17, 2006 | 04:38 PM

chevydad

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From: latrobe, pa

did you set the idle mixture screws?some of the demons had a idle adjustment in the center of the carb where the aircleaner stud would go.

possible air leak?

Nov 17, 2006 | 05:24 PM

Vcious04

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From: Alvarado, Texas

More that likely it's the idle mixture screw's. I always turn them all the way in, and them back both the front 2 out 1.5 turns each. If yours has rear idle mixture screws, turn them all the way in (off), no adjustment.

Also, turn your fuel pump on only and check your float levels. Very critical..

I have never used speed demon carbs before so this might not help very much. I am VERY familiar with 4150 style holley's..

Nov 17, 2006 | 07:42 PM

PRAY HRD

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From: CISSNA PARK, IL

Quote:

Originally Posted by Vcious04

I have never used speed demon carbs before so this might not help very much.

ok, first of all, your sig says you're running a speed demon carb on you mustang.

i'm just making sure i'm not missing something here.

second, have you posted pics of you conversion yet because if you haven't, shame on you!

i'll try doing a search for it now, but i'd love to see & hear more about it. feel free to shoot me a pm too please.

-Dave-

Nov 17, 2006 | 09:49 PM

LQ4Monte

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Sounds like a good old vaccum leak to me. Spray carb cleaner around the base gasket with engine running or stick you hand over the carb (watch out for carb backfires if you do this) and manually choke the carb. As Vcious04 said return every thing to default to make it easier to get the engine running. A vaccum gauge is a handy tool when tuning a carb. Hook it up to a port and check vaccum reading.

Another thought it could be you are idling on the primaries and when you bring the idle down you go dead rich or lean and the engine dies. If you have a manual for the crb read it twice. If nothing else give demon's tech line a call or email them.

If I remember right the newer speed demons have idle ease which allows additional air flow in the idle circuit. Just like when the old boys drilled the throttle blades on holley's to get rid of off idle stumbles.

BTW it is always a good thing to have extra carbs sitting around if you are having issues. I had/have an old carter AFB that I have used as a baseline carb when I couldn't figure out what was going on with a car.

Nov 18, 2006 | 10:03 AM

caged02

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From: Altoona, Iowa

Thanks everybody for the advice, I pulled out the plugs and they were black. We jetted the carb down and cleaned up the plugs and that helped alot. I was running a #6 pill and I think that was a lot of my problem. I talked with TJ on here and he said he has the best luck with the #1 pill. So I am going to try that and see what happens.

Nov 18, 2006 | 12:19 PM

Vcious04

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From: Alvarado, Texas

Quote:

Originally Posted by PRAY HRD

ok, first of all, your sig says you're running a speed demon carb on you mustang.

i'm just making sure i'm not missing something here.

second, have you posted pics of you conversion yet because if you haven't, shame on you!

i'll try doing a search for it now, but i'd love to see & hear more about it. feel free to shoot me a pm too please.

-Dave-

Dave, thats funny, I did not relize I still had that in my sig. I was going to try a speed demon but relized it was built differently than a 4150 style carb.

I am on dialup and sending pics takes forever. But I am at work now and can send you some pics through email and you can host them for me. Thanks man.