M38 Carburetor adjustment

Jim · Post by **Jim** » Mon Jun 07, 2010 5:56 pm

My manual on the carb doesn't discuss how to adjust
the idle screw. Mine is a rebuild and I need to make sure
it is adjusted correctly. I assume (dangerous) that you
start from a fully seated screw and adjust it outward some
specified number of turns. Is this correct and if so, how
many turns out? Thanks!

Jim in Darkest Arkansas

MODIFIED · Post by **MODIFIED** » Mon Jun 07, 2010 7:56 pm

I'd measure best mixture via Vacuum gauge.
-start and warm veh to oper temp
-install vacuum gauge and notice reading
-carefully close (clockwise) idle mix screw (do not not jamb !!! or force tight!!"
-let out (counterclockwise) 1/4-1/2 turn and adjust to best vacuum reading.

Post by **wesk** » Mon Jun 07, 2010 8:36 pm

The standard setting for this carb is 1 1/2 turn out from fully seated. Start there and adjust per manual.

The adjustment procedure is in your M38 manual TM 9-8012 page 151.

Jim · Post by **Jim** » Wed Jun 09, 2010 3:32 pm

Thanks, Wes. Page 151 didn't have the number
of turns of the screw.

Jim in Darkest Arkansas