Best Way to set the idle mix on a 4160

steve meltzer · #1 (**permalink**) 03-01-2018, 05:49 PM

oops. i didn't see the picture you referenced in your long and detailed instructions. thanx. s

patrickt · #2 (**permalink**) 03-01-2018, 06:40 PM

I can not emphasize enough the role of the transition slot, and the positioning of the throttle blades along that slot, in getting your engine to run right. You have a big FE, a healthy cam that lowers your vacuum, along with hot under hood temps. If you have your throttle blade up deep in to the transition slot, then you're negating the effect of the idle mixture screw and actually defeating the whole purpose of the transition slot to begin with. The transition slot is really a beautiful little engineering design. When your throttle blade is down at or below the bottom of the slot then the slot is actually feeding fresh air in to the emulsified fuel. But as you open the throttle, and the blade moves up the slot, the portion of the slot that is below the blade grows larger and brings in more pure emulsified fuel instead of air -- it "transitions." It's a beautiful, simple design.

steve meltzer · #3 (**permalink**) 03-02-2018, 06:33 PM

Patrick, thanx again. let me digest this and get some wrench time in, hopefully, this weekend. my life and job are interfering with my fun. s

patrickt · #4 (**permalink**) 03-02-2018, 07:14 PM

Quote:

Originally Posted by steve meltzer

Patrick, thanx again. let me digest this and get some wrench time in, hopefully, this weekend. my life and job are interfering with my fun. s

Alright, get cracking... and remember the Club Cobra Credo: "See One, Do One, Brag About One."

steve meltzer · #5 (**permalink**) 03-02-2018, 08:08 PM

Hmmm....vaguely like my residency training...see one, do one, teach one...
and our credo: we teach the unteachable, train the untrainable and accept the unacceptable.

s
(now sporting a tee-shirt with a frog that says "don't croak on my shift")

steve meltzer · #6 (**permalink**) 03-03-2018, 11:23 AM

OK, carb off, but I can't get the primary butterflies to close anywhere near the "perfect little square" that closes the transition slot the way it should be. Primary idle speed screw is all the way out. thanx. s

steve meltzer · #7 (**permalink**) 03-03-2018, 12:22 PM

Me bad and dumb...choke was in play! Now my problem is that the blades don't close evenly. It's slightly tighter on the left (driver's side). Can this be adjusted so that they close evenly? I would hope so. is it the "stake" screws that screw into butterfly itself, on the bottom of said butterfly? thanx, supernovice, steve