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Setting 4 corner idle circuits

Old 05-19-2002, 02:37 PM
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voodoo
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Default Setting 4 corner idle circuits

Is there a proper way to set these idle circuits on a Holley with the 4 corner idle? I feel I have it close one time and then it stumbles the next. When it is cold it idles fine, but once I run it and get everything up to temp it acts as if it is loading up. Any ideas? I am fairly uneducated about Holley carbs.
 
Old 05-19-2002, 03:49 PM
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The float level could be a little on the high side. You ever set the float level on a holley before? I'm not trying to be a smart-ass, I'm just asking how familiar you are with Holley carbs, as the float bowls can be stripped out very easily if you overtighten the needle-seat nut.
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Old 05-19-2002, 04:39 PM
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I like to use a vaccum gage while adj. them and the motor up to full temp. James
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Old 05-19-2002, 04:52 PM
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I did raise the float levels before the weekend as they were 1/4 inch below the sight hole, I may have gotten them too high. If you use a vacuum guage, where do you attach? Is there a place at all 4 corners to put a guage???
 
Old 05-19-2002, 07:30 PM
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Get the level right,On my 850 I use the port that is on the base of carb on back side,or use a port on the manifold,set the first idle-mixture screw to register the highest reading then the second then the back side the same way. Now do all four again and then check idle speed you might have to reset idle speed down if it came up to high. James
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Old 05-19-2002, 08:21 PM
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Do you set the float levels with the boat as it would be at idle or as it would be running. I will be doing this on the trailer. Seems to me you would have to pick a happy medium such as getting the carb as level as possible. With float bowls on front and back it is all a compromise.
 
Old 05-19-2002, 08:29 PM
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The float bowls should be set with the boat in the water for best results. They should be just at the bottom of the sight glass plug. Make sure it is the bottom!!! It seems about 90% of the carbs I see are set to high. Then turn the idle screw in until the motor stumbles and then back it out 1/2 turn. You have to do all of the screws a couple of times to get it right. You should set the idle with the motor warmed up. If you still have problems you may have a blown or are using the incorrect power valve and it is dumping fuel at idle. Check all of this out and if yopu are still having problems let us know and we will certainly give you more things to try. I've been there many times. Good tuning!!!
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Old 05-20-2002, 12:09 AM
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Level at the water would be the best angle to set this up...

I found that the Holley's have two issues... When a boat
accelerates it pushes the fuel backwards alot more than a car
would. So, two additions were made (used). One, make sure the
"straw" to the upper vent hole is still in place and second, is add
jet extenders in the secondaries. This allows the fuel to get where
it needs to go regardless of the float settings. The "straw" in the
secondaries might go under the fuel level causing the stumble
which would give a false reading. By eliminating the "straw" and
adding the extenders corrects this situation.

The four corner idle screws are something that needs to be
learned by experience. I am no Holley expert... yet I have
learned through my friends that hearing the engine "stumble"
(which is what we have heard earlier) is the experience and add
the use of the vacuum gauge makes it all work best.

P.S. They still help me to tune this thing up to make it work...
 
Old 05-20-2002, 12:32 AM
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Assuming your floats are set correctly, you need set the idle mixture with the boat at operating temp. Let it run for at least 10 mins. If its idles fine cold as you say, then you probably are rich at operating temp. Neither one of my boats (no chokes) will even stay running at idle when I first start them. Have to run them 1200-1300rpms for a couple mins. first. Once warmed up the idle perfect.
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Old 05-20-2002, 11:36 PM
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Bruce built my 540's for me and I was asking him about setting the carbs. Engine has to be up to temp and he suggested tieing up to the dock and setting air mixture screws while it was in gear. wette vette was right about the stumble and then 1/2 turn out. I did that way and it seemed to work fine. I really don't think I am getting as much soot on the transum doing it that way. Does anyone else do it in gear ? I never heard of the vacuum guage deal. I really like that. FloridianSon do you only go to the highest reading and stop or give it a 1/2 turn out ?
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