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 Post Posted: Mon Jul 19, 2010 4:29 pm 
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I bought a freshly rebuilt 706ci, donovan block, pontiac head, motor. Eagle racing orginally built the motor. It was recently dynoed at 1240hp at about 7200 rpm. It has split dominator 1150 carbs. It starts easy but won't idle. I let it warm up for awhile by wiggling the throttle to keep the squirters going but then try to hold the rpm at 1500rpm and it dies. If I hold it steady at 2000prm it dies. The carbs came from pro-system.com. They call the setup a pro 1V. Has anyone used these people? If the motor is really warm (200 degrees) it idles fine but at about 900rpm. Any ideas? I plan to bracket race with the thing and dont want to worry about stalling on my way to the lights. Thanks.

Ty


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 Post Posted: Mon Jul 19, 2010 6:54 pm 
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That carb builder has mixed feedback here. Some love him, others hate him and you can put me, Donee and Ron Owens (and maybe others that I don't know about) in this later group.

My guess is that once you put heat in it then it should be OK the rest of the day. Not wanting to idle at cold startup isn't unusual especially if it's clean and lean there when it's hot. IMHO the only way to make it idle cold like it does when it's hot is to richen it up, then it's going to be too phat when it's hot. THAT is the reason they put chokes on street cars.

If you haven't already tried this, I'd try it at the track during a test and tune to see how it acts. That way you will have a better idea of what you are working with under something near race conditions.

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 Post Posted: Mon Jul 19, 2010 7:01 pm 
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First thought is a vacuum leak. When did the problem start? Have the carbs been rebuilt recently? How did they run before?


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 Post Posted: Mon Jul 19, 2010 7:06 pm 
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As Ken said your best bet is to go to a test and tune to see how it actually performs. If it runs OK once you get up to about 200° you're probably just a little too lean on the idle calibration of the carburetors. There are a couple of things to keep in mind when tuning splits to start off with:

- First make sure all of your butterflies are open the same amount

- Make sure your mixture screws are set the same

- Make sure your float levels are set properly for the carburetors

- Lastly, Tune the idle at the same Temp you're going to be running and staging the engine at. I'd guess you're not going to run at 200° so I'd try to tune the idle a little closer to where you'll be running.

- Mike and Chad build really strong engines, and should be able to help you with a bracket setup since Chad does a fair amount of bracket racing.

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 Post Posted: Mon Jul 19, 2010 10:38 pm 
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What kind of timing curve do you have? You don't want to have the timing changing at all until at least 2000 rpm.

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 Post Posted: Tue Jul 20, 2010 11:57 am 
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I love this forum. Thanks for all the great feedback. The timing is fixed at 28 degrees. I'm told that is normal for a motor like this. The motor was dynoed at 28 degrees. I'm going to check for vacume leaks, mixture screw setting, equal butterflies, and go see how it acts at a test and tune.


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 Post Posted: Tue Jul 20, 2010 12:56 pm 
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fasthappy wrote:
I love this forum.


Ah, then why did you stay away so long? O:)

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 Post Posted: Tue Jul 20, 2010 3:52 pm 
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Ken0069 wrote:
fasthappy wrote:
I love this forum.


Ah, then why did you stay away so long? O:)


The recession here in So California is bad and I just started working more trying to stay afloat. Too much work and not enough play means no racing or wrenching and not much to talk about on a car forum. I checked in from time to time though but I've decided to play in the garage more. It keeps me smiling and I like learning new things.


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