[chuck560sl]

I have read about mixture adjustment by using a duty cycle reading off pin 3 of the test connector and looking for a 50/50 reading.

I don't have a multimeter that reads duty cycle but I did take an rms reading.

the measurement read 6.6v initially and with a slight adjustment it went up to 6.7v and then started to go back down again. I adjusted for 6.7v and rechecked. Either way I turned the voltage would start down again so at 6.7v I assumed I was at 50/50.

I read somewhere that the voltage should be somewhere between .5v and .9v so I do not understand where the +6v comes in unless it was a bias reading to chassis ground.

Also at that point I am idling close to 1000 rpm. When I add drive and air cond it idles at 650 - 700 and the engine runs smooth in all instances.

Does anyone have some experience with this type of adjustment.

Thanks,

Chuck

 

[chuck560sl]

Well for all those interested. I played around with this theory and I believe it does work. Measuring the ac component of a squarewave to get a 50/50 duty cycle.

When I finished I was right on. 1/4 turn left on the mixture would get a little engine cycling. 1/4 turn right I would see some discolorization in the exhaust.

So right in the middle of those observations is where I set it voltage wise. Seems to be right and according to theory.

Car now runs smooth, clean and strong.

Chuck