Idle adjust

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akblackdawg
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Idle adjust

Post by akblackdawg »

still trying to get my new motor dialed it. idle temp at 180, air cleaner off, can set to idle at 500, it slowly goes up to 600-700 and then fluxuates between 600-900 for a couple minutes, then up to 1200 and run there a couple minutes, then back down to 500-600 and starts the cycle all over again, all this over a span of 3-4 minutes. Whats the problem? why won't it idle it constant speed. return spring is tight, no wobble there, carb is only a year old. what do i need to look at. Bud
:alaska: If you ain't living on the edge, you're taking up to much space.

15x8 Alumatech hull, with enclosed cab, aluminum cage, LS 3, 6.2 aluminum block ffi, 2.7 Balistic Box, sensinich superwide 3 blade. Built for year around riding in Alaska

Aeon
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Re: Idle adjust

Post by Aeon »

Do you have a choke and fast idle cam on this carb?....i always run no choke but that is just me. Even at 22deg starting is zero problem. best guess is a malfunctioning auto magical choke. NO clue by the way how a BBC starts at -50 for you AK people.

check the normal stuff, vacuum leak someplace, base plate leaking air, problem in the dizzy and your timing jumping around.

BTW i was just in your hood and caught a ton of your king salmon! :) thanks
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

loudmouse
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Re: Idle adjust

Post by loudmouse »

Sounds like your idle air screws need adjusting or you have a vacuum leak. If it is a Holley carb they are located on the sides of the metering blocks. Some carbs have two and some have 4. Set them by turning all the way in and backing out one full turn. Crank engine and adjust them all the same out a lil at a time until ur idle rpm levels out.
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One Eyed Gator
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Re: Idle adjust

Post by One Eyed Gator »

Something I just had happen recently. New cam I put in has very little vacuum at below 700rpm. As it would idle down power valve would open, caused it to stumble then it would catch-up and idle high. above 700 it was around 12" but below that it would bounce between 3-5. Took a little time to figure out.

Sure runs good Now.

Just something to check.

flying fish
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Re: Idle adjust

Post by flying fish »

Bud

Try this same experiment with the air cleaner on.- PRop may be pulling fuel out the bowl vent tube.

Possiblilties-
1) Too much fuel pressure blowing needle off seat.
2) Vacuum leak
3) Idle air screws, screwed in too far
4) If you had a manual choke, and this choke has been removed, you have an air leak on the carb main body where choke mechanism unbolted. \
5) Fuel pump not keeping up.
6) squirter linkage adjusted too tight-- no slack in linkage.

If you can position yourself to look into the bowls while engine is running, you may be able to see where fuel is entering into carb when idle speed increases.

IMO-
That big prop pulling fuel out of the fuel bowls through the bowl vent tubes when air cleaner off. :)
15' DB - 6.2 LSA - 4 blade 82" R - 2.52 CH-4

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akblackdawg
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Re: Idle adjust

Post by akblackdawg »

Thanks Chris, will try it this afternoon. No choke, carb was set up by moonrisin in Houston, S&S. I took blades off and now idle around 2000, will look at that this afternoon and see if i can get it down. Bud
:alaska: If you ain't living on the edge, you're taking up to much space.

15x8 Alumatech hull, with enclosed cab, aluminum cage, LS 3, 6.2 aluminum block ffi, 2.7 Balistic Box, sensinich superwide 3 blade. Built for year around riding in Alaska

flying fish
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Re: Idle adjust

Post by flying fish »

Bud
Unhook your pedal linkage. Get her fixed without throttle linkage hooked up

The Holley has a rear adjustment on idle just like it has an idle adjustment on the front barrells.
Understand what your transition slots are, and adjust butterflies where you can just barely see transition slots front and rear on venturi's. You have to have the carb off the engine and upside down to properly adjust for transition slot exposure.

The rear butterfly idle screw can be found when carb is upside down.
When you adjust front barrell idle, you should adjust rear idle equally. This keeps transition slots exposed equally.

Understand what your transition slots are and adjust your idle screws accordingly.
Make a note of what tools you out.

Lots to know for such a simple adjustment. You can do it right. Be safe :)
15' DB - 6.2 LSA - 4 blade 82" R - 2.52 CH-4

myronja
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Re: Idle adjust

Post by myronja »

Also check the squisher adjustment any time u adjust idle it changes the squisher lag. Should be just touching the squisher arm. Just a thought.
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Birddog247
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Re: Idle adjust

Post by Birddog247 »

The squisher arm may also realign the muffler ball bearing which could cause your blinker fluid to get low. Never hurts to ask the experts. Lmfao


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pierce44
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Re: Idle adjust

Post by pierce44 »

Birddog247 wrote:The squisher arm may also realign the muffler ball bearing which could cause your blinker fluid to get low. Never hurts to ask the experts. Lmfao


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About the same problem I was having, BFH fixed it !
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