Fast idle
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=47835
Printed Date: April-28-2024 at 10:59am
Topic: Fast idle
Posted By: Dellavalle
Subject: Fast idle
Date Posted: July-29-2019 at 5:46pm
| Correct Craft 1982, Holley four barrel, running perfect except for idle at 2K. / tried just about everything. Cleaned, fresh gas, retarded choke ( electric) idle screw all of the way out, still at 2 K. ./ Suggestions ? Engine Ford 351. |
Replies:
Posted By: KENO
Date Posted: July-29-2019 at 6:11pm
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What happens if you disconnect the throttle cable from the carburetor, does it still idle high? Maybe you just need a throttle cable adjustment |
Posted By: Jonny Quest
Date Posted: July-29-2019 at 10:42pm
Please elaborate on "idle screw all of the way out". Do you mean that the throttle valve is completely closed? Also, are you referring to the "curb idle" screw or the idle mixture screws? For reference, see the diagram below of a Holley 4160 (non -marine, but you get the idea):  If the idle mixture screws are all the way closed, then the engine won't run unless the throttle valve is open far enough to engage the primary circuit. Verify the position of the 2 carb idle mixture screws. If the idle mixture screws are not fully closed, gently screw in (clockwise) the 2 idle mixture screws until they are lightly seated. Then back the screws out one and one-half (1 1/2) turns. That is a good place to start. As KENO mentioned, remove the throttle cable linkage from the carb to ensure that the throttle valve linkage is closed against the throttle stop. Then start the engine. With the throttle cable disengaged, now try to set the warmed-up idle to 800 RPM. If you have access to a vacuum gauge, you can then tweak the idle mixture screws by using the vacuum gauge connected to "full manifold vacuum". Start by turning 1 screw in or out by 1/8 turn. See how the adjustment affects the vacuum. Adjust the idle mixture screws so that you get the highest vacuum reading at idle. Typical screw settings on a 4160 that I've seen run between 3/4 to 2 1/2 out from gently seated. A blown power valve can also affect idle. If your carb has never been re-built, it may have an older style power valve that was susceptible to blowing out. Check closely for vacuum leaks. A vacuum leak will make the idle do strange things. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Dellavalle wrote:Posted By: Dellavalle
Date Posted: July-30-2019 at 10:35am
| Thanks for the help. On the opposite side of this diagram, is the "primary throttle shaft assembly" the screw that will increase the RPM's is in between this assembly and the main carb. body. / I have not touched the idle mixture screws as of yet / Engines starts and accelerates perfectly, just the idle is fixed at 2,000 rpm. / engine is all warmed up to temp also, and flies. . |
Posted By: Dellavalle
Date Posted: July-30-2019 at 10:38am
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Thanks. Cable disconnected, still at 2 K., Next try will be the idle mixture screws, any ideas? Thank you again for your suggestions, P.D. |
Posted By: KENO
Date Posted: July-30-2019 at 11:01am
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How about a little history, did this just mysteriously start idling high or did you do something right before it started. What do you mean by cleaned, disassembled and cleaned the whole carburetor? Are your secondaries closed against the stop set screw and not hanging open a little? Have you checked the timing lately? |
Posted By: KENO
Date Posted: July-30-2019 at 11:07am
Click on the link below and check with that guy, he had the same problem 6 years ago and fixed it...................but didn't say how, I think you might know him  http://correctcraftfan.com/forum/forum_posts.asp?TID=30332&KW=&title=holley-carb" rel="nofollow - link |
Posted By: Dellavalle
Date Posted: July-30-2019 at 3:52pm
| Yep, installed a new fuel pump, fuel filter. . |
Posted By: KENO
Date Posted: July-30-2019 at 7:36pm
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Not sure how a fuel pump and fuel filter fixed your original high idle Maybe you should try the same thing again IOne thing.............f you're shifting that thing in and out of gear at 2000 rpm, you should be getting yourself ready for a transmission overhaul and damper plate replacement sooner rather than later |
Posted By: shierh
Date Posted: August-04-2019 at 12:19am
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i bet your secondaries are not closing all the way |