Best Way to set the idle mix on a 4160 - Page 2

steve meltzer · #1 (**permalink**) 10-14-2018, 08:02 AM

I was thinking that, but there are so many moving parts that i wasn't sure. If the carb isn't perfectly square on the intake it wouldn't take too much for something to bind and get cattywampus. thanx. s

steve meltzer · #2 (**permalink**) 11-18-2018, 11:42 AM

OK, took the carb off the car so I could get a better idea about what the heck is going on with this sticky throttle. I believe that the small, curved/bent rod that links the primary throttle mechanism to the secondary shaft (on the left side of the carb) was causing my problem. By bending and straightening that linkage rod mechanism, the primary now moves easily and freely. Have yet to drive the car, but it seems like a good start, as, on the bench, the accelerator arm moves perfectly.

Also, the carb leaks fuel from the passenger's side. Bowls and Accelerator pump appear to be dry and not the source of the leak. How do i proceed to the diagnosis?

thanx, and sorry it has taken so long to get back to this. s

thanx so much. steve
(I can post a picture if anyone is interested...just need to move to another computer)

patrickt · #3 (**permalink**) 11-18-2018, 11:55 AM

Alright, that's progress... I think.

. That little rod on the driver side of the 4160 serves to close the secondaries, should they be open, when you lift your foot off the throttle. There should be no binding, tightness, or stiffness. Having a little "looseness" to it all is normal. To diagnose your fuel leak you should use ultraviolet dye and a black light. Do not be misled by fuel leaking out the throttle shafts because you squirted gas on to the primary butterfly valves while you were testing for binding over on the driver's side linkage. Make sure your bowls are filled up normally (just by running the engine and then shut it off). Put about an eye dropper full of uv fuel dye (available on Amazon) down each vent tube of the carb. That's one for the primary and one for the secondary. Then DO NOT TOUCH THE CARB and under no circumstances work the throttle to induce a squirt. Watch the carb for the next couple of days under the black light. Look around the bowl gaskets, metering block gasket, the little cork gasket around the idle mixture screws, and everywhere else. Then report back.

steve meltzer · #4 (**permalink**) 11-18-2018, 01:53 PM

Great! thanx Patrick. much appreciated.
Wonder if i can use cat piss for my UV dye...it shows up (everywhere at my place) with a black light! s

patrickt · #5 (**permalink**) 11-18-2018, 01:56 PM

Quote:

Originally Posted by steve meltzer

Great! thanx Patrick. much appreciated.
Wonder if i can use cat piss for my UV dye...it shows up (everywhere at my place) with a black light! s

Only if you consider your engine bay to be equivalent to a litter box.

patrickt · #6 (**permalink**) 11-18-2018, 03:19 PM

Oh, and you'll need a little mechanic's angled mirror to see under the fuel bowls at the base of the carb. The way you do it is angle the mirror so you can see the gasket line at the base of the bowl and then shoot your black light so it bounces off the mirror and hits the underside. Of course, you should see no signs of fluorescence for at least three days or more. Do it in a totally black garage and you can't miss finding the leak.