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[SOLVED] High idle after Carb rebuild


b3y0ndd34th

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Hello All, it's me again, that guy with the Primer Grey 75 610 Goon.

 

I know you're all going to tell me to take the carb off, throw it as far as possible after maiming, or torchering the device with a sledge hammer, but I REALLY need help, this it the only Carb I have, and if you want to send me a holly, edelbrock, or something worth while I am open to gifts, but I am strapped for cash and don't have the funds to play with right now.

 

I have the stock L20B still installed with a replacement Hitachi carb that Eagle_Adam so kindly sold me last year. The carb has been doing great, but he told me I should probably rebuild it.

 

Well I finally got around to doing that, after I rebuilt my first Hitachi I figured the second would be much smoother. I did so on my kitchen table in a cuple of hours.

 

I installed the carb, fired my car up, and now she wants to idle at about 4K. She starts at a low rpm (800-1000) and then climbs to 4K, I've tried retarding the timing but it does not help. I have my idle air set screw about 1 and a half turns out, I did not adjust this during rebuild, I have tried it as far as damn near falling out, it does not affect my idle in any way. I did not mess with the Idle set screw while rebuilding either, I have turned it out a few turns then back in as it also had no affect on the high idle.

 

Finally this brings me to you guys. This is my first Carbureted engine so some of this stuff is still new to me. I replaced the float, had problems with it getting too much gas, I have adjusted the float properly. I have replace the Needle Air Filter fella on the carb itself, as well as replaced the in-line fule filter, and plugs.

 

Side note, the Fuel pump, plugs, wires, distributor cap, and button, set points, are all new, next is timing when I get the chance.

 

But for the time being what can I do to get my engine to idle down?

 

My high cam seems to be functioning properly, as far as I can tell. I can drive it this way, I don't mind, but for my motor's sake I'd like to get my idle at a more acceptable rate.

 

Thanks for the help!~

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Make sure the air jets (visible on the exterior top of carburetor) are not loose.

 

Next, with engine off, look at the throttle linkage. Open the choke blade with your fingers, then open the throttle and let the throttle snap back. Does it close all the way, or is the Fast Idle cam still holding it open?

 

Take it a step at a time, methodically.

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Check that the primary barrel (closest to the valve cover) is closed. It should only be open a hair and held open by the idle adjustment screw.

 

Check the secondary barrel is closed tightly. Look down in there with a flashlight.

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I agree with GG /\ /\ That picture shows the butterfly (throttle blade :)) being a lot more than "cracked open"........the fast idle cam is prolly active and I would guess the choke wire may not be getting any power? As the choke coil warms it will open the silver flap (choke) and allow the fast idle cam to move out of the way.

With the engine off, push the choke flap open fully and tap the throttle and it should allow everything to close up back to idle (you will normally hear a "click" as the fast idle cam's spring unloads).

I only run these great carbs.........they are very easy to tune are well worth keeping IMO.

BTW....let me know if you truly can get it together and switch to something else, I am always looking for these carbs :)

good luck!

--Ray

 

IMAG0337.jpg

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Also.......check and make sure the secondary butterfly is closing fully......I'm thinking the pic above is showing the sec blade open and NOT the primary?! Reach under the carb (if still mounted on the manifold) and push the secondary linkage and see if that's it.

:)

--Ray

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i had this happen to me once with my lawn mower...i know its not a carb from a car, but i removed the butterfly flap and installed it backwards(after rebuild)...long story short..it wouldnt idle right or run under throttle. good too see you got it going tho!!

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They are removable but very difficult to get back in the exact same place or it won't close the bore tightly. Many carb makers rivet them or peen the threads so they can't easily be removed.

 

Yeah I noticed it was a pain to get back in there right :D Lesson learned, next time I'll leave them alone! But on the good side I KNEW it was something I did to it to mess it up so I could fix it :D

 

 

Next I'll upgrade the craptachi to a weber, but that will take a few months of saving I fear :(

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