66 lark8,low speed needle valve question

glassmaster68

Petty Officer 1st Class
Joined
Feb 17, 2010
Messages
227
book says 1 and half turns out ,go in until spits then back out till rpm goes back up,,,mine seems to run good at the 1 and half turns,,,rather foul a plug than kill a piston but my question is ,,does anybody know the average "sweet spot "for the low spd nd vlv on this type 2 carb on a 66 40hp,,,,,,,and does this matter at wot since theres a fixed oriface? i assume the air on that is also fixed ?just dont want to scald the pistons
 

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: 66 lark8,low speed needle valve question

If it is too lean, it will spit and cough at idle. If it runs fine at 1-1/2 turns, then leave it there.
 

a70eliminator

Captain
Joined
Sep 9, 2007
Messages
3,688
Re: 66 lark8,low speed needle valve question

Your absolutely right the low speed idle doesn't effect high speed operation, look closely at the needle to verify the tip isn't broken and look for wear along the tapered portion, a worn needle will look like a ring around the tapered cone caused by the needle being cranked into the seat. I feel as long as your needle is responsive your good, on mine one quarter turn in from the sweet spot will kill the engine either side.
 

glassmaster68

Petty Officer 1st Class
Joined
Feb 17, 2010
Messages
227
Re: 66 lark8,low speed needle valve question

thanks a70,,yeah needle tip is good,not many hours on this motor,,,so if its too lean it will cough and spit,thats about a quarter,,in that case a half to 3/4 might be right for me ,,it still idles good that much in,,,so if i have good sounding idle,,it wont burn it up?thats all im afraid of
 
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