1974 chrysler 70hp model 707hf engine idles too high rpm. how reduce?

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christo555

Seaman Apprentice
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Aug 12, 2010
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just got this motor and it runs great once you get it started, but the idle speed is very high, like 2000rpm. how do you adjust the idle speed? the idle mixture screws work to make it run smoother,but don't affect the idle rpm.
thanks for any help, newbie
 
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Nordin

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Re: 1974 chrysler 70hp model 707hf engine idles too high rpm. how reduce?

You have a setscrew with a locknut for idle at the towershaft, it makes the shaft to stop against the engineblock. Idlespeed about 700-800rpm in gear. DON'T play with the mixturesetting at the carbs, read Franks sticker about timing/carbs sync. 1-1 1/8 turns out from bottom. AND never less then 3/4 turn out then you may melt pistons. I have my carbs for my 1970 70Hp and 1976 75Hp 1-1/8 out, works exellent.
 
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christo555

Seaman Apprentice
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Aug 12, 2010
Messages
49
Re: 1974 chrysler 70hp model 707hf engine idles too high rpm. how reduce?

nordin,
thanks for the info. i worked on the problem again after posting and found that one of the three carbs throttle valve was partly open in the idle position. after making sure they were all closed at idle, i then used the idle adjust on the tower shaft to get about 800 rpm at idle.
now, i have to find a used/good choke solenoid for this 707hf as mine pulls in fine, but doesn't release. it stays jammed inside. i am using a nail for a stopper where the solenoid connects to the operating rod so the plunger doesn't pull in so far and it does release but because it doesn't choke 100%, it is hard to start when dead cold. any idea about where to get solenoid or repair the one i have??? anyways, thanks again for your reply, the only help i got. vollbob
 
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