wont idle..
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Old May 2nd, 2009, 10:12 PM   #1
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wont idle..


I know the motor in my car has a radical cam in it and won't idle smooth, but for the life of me I can't get it to stay running at idle for more than ten seconds..

Timing is very close to being set correctly.. maybe +2- deg
Fuel pressure is set at 7.5 psi..
If I hold my foot on the gas lightly it will sit there and idle fine..

not really sure what to look into first. anyone have any ideas?
I'm not too familiar with carbs, mostly done fuel injection, but I think maybe I need to adjust my float level..
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Old May 2nd, 2009, 10:15 PM   #2
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try adjusting the idle set screws to bump the idle up a little bit other than that you probably just need a good tune
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Old May 2nd, 2009, 10:19 PM   #3
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alright. I don't have a good tach in the car, so I have no idea what it's trying to idle at. I know long duration camshafts should idle around 1200/1300 .. it might just be at about 1000 rpm and doesn't like the surging idle/low vacuum.
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Old May 2nd, 2009, 10:26 PM   #4
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a cam with a huge amount of duration is always gonna have a pretty rough idle but it shouldnt' die so yeah just try those things
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Old May 2nd, 2009, 10:59 PM   #5
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What kind of carburetor? Get familiar with it. Buy a book on it and learn. Carbs are as complicated or more complicated than EFI. There are many things that can cause these issues but if you are not familiar with carburetors then it is all going to be greek to you.
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Old May 3rd, 2009, 01:26 AM   #6
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check your idle screws on the side and make sure they are all the same length out. screw them in all the way and put them all at about 1 and a half turns out. try that for starters, but like darrell said, there are SO many things that could be your problem.
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Old May 3rd, 2009, 10:11 AM   #7
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Originally Posted by 89LX347 View Post
check your idle screws on the side and make sure they are all the same length out. screw them in all the way and put them all at about 1 and a half turns out. try that for starters, but like darrell said, there are SO many things that could be your problem.
The correct way to set the idle mixture is with a vacuum gauge and set them for the highest vacuum. They won't necessarily be turned out the same amount on each side. I'll guarantee this isn't his problem though. I'm willing to bet the throttle blade is open too far exposing too much of the transfer slots.....for starters anyway. He is about to find out why I say EFI is easier than carburetors.
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Old May 3rd, 2009, 12:49 PM   #8
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Originally Posted by Darrell View Post
The correct way to set the idle mixture is with a vacuum gauge and set them for the highest vacuum. They won't necessarily be turned out the same amount on each side. I'll guarantee this isn't his problem though. I'm willing to bet the throttle blade is open too far exposing too much of the transfer slots.....for starters anyway. He is about to find out why I say EFI is easier than carburetors.

Hogwash darrell, he just gotem sum gremlins init.
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Old May 3rd, 2009, 12:59 PM   #9
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Originally Posted by JBIGBOOTSY View Post
Hogwash darrell, he just gotem sum gremlins init.

i know how to get rid of gremlins....shave one side and burn the other....o wait maybe i thinking of something else
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Old May 3rd, 2009, 01:00 PM   #10
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Old May 3rd, 2009, 01:42 PM   #11
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alright, thanks for the help guys.

It would sit and idle fine for minutes on end before, but the only thing ive changed was my alternator .. (changed the fuel regualtor back to 7.5) because of the added volume of the fuel.

Perhaps my throttle return spring is too stiff and pulling the throttle blade beyond base idle if that makes sense. Ill adjust the idle screws out to the most vacuum.
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Old May 3rd, 2009, 05:57 PM   #12
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so i think i figure out what's up with the idle problems. It's a fuel pressure problem..

I turned my key on (fuel pump primes) and i hear a bunch of noise coming from my fuel pressure regulator and the needle is bouncing like crazy and doesn't sound good. I've had nothing but problems from this regulator. First the nipple on the back side wouldn't seal because of lousy machining, so i had to ghetto jb weld it, not the diaphragm isn't holding pressure..

Can anyone link to me a fuel pressure regulator that will hold up to a large efi pump but drop pressure down to 8psi or so?

Mine currently is a mallory. I think they should just stick to ignitions.
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Old May 3rd, 2009, 06:13 PM   #13
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aeromotive will have a good one, but if its not an intake pump, think about a non efi pump
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Old May 3rd, 2009, 06:27 PM   #14
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well it needs to be a return style regualtor, single inlet single outlet
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Old May 3rd, 2009, 07:15 PM   #15
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after reading on the topic more, people who run the stock efi pumps are having trouble with steady fuel pressure.

What else have everyone done that has gone from fuel injection to carb? I don't care about spending a hundred bucks or w/e as long as it fixes this problem once and for all!
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Old May 4th, 2009, 01:32 AM   #16
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Originally Posted by superbean View Post
after reading on the topic more, people who run the stock efi pumps are having trouble with steady fuel pressure.

What else have everyone done that has gone from fuel injection to carb? I don't care about spending a hundred bucks or w/e as long as it fixes this problem once and for all!
That is because you are using the wrong parts for the job. Mixing and matching shit just to save money always results in problems like this. Put a low pressure high volume carb pump and regulator on the car and be done with it.
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