Got the spring installed today and everything went pretty well except for the usual snafus. Pulled the top cover off and the diaphragm came out stuck to it so I figured great, no need to mark it. There was some seemingly useless silly sheet brass cover on the high idle screw nuts that was hard to get off. Got the spring in and all put back together. But when I picked up that top cover, of course the diaphram fell out on the floor.

So I just threw it on and started it, wouldn't idle. Took the AFC cover off and back on, turning the diaphragm several degrees a dozen times or so until I realized what I'd done. The throttle lever was one spline off. Fixed that and it idles fine and runs like the proverbial scalded dog now (as someone else here likes to say, as I reacall.)

So my question is: What are the implications of that diaphram being installed basically randomly? It is making some black smoke under hard throittle now, but seem to run fine, better actually. Is there any way to determine what the deal with that thing is now after the fact?

Tks...

 

The diaphram really isn't a real fine adjust ment but for best performance you should put the inner most tappered part facing the rad

 

If you really want to know where it was set before look at the cone, you can see where the pin contacted it, that would be toward the front of the truck. For the most aggressive setting, rotate the diaphram/cone to the deepest part of the cone(part where pin can travel furthest to the back of the truck).

 

Great, once again I have a clue! Now for taking that cover off one last time. On the subject of idling, can anyone advise what a good idle setting might be? It was at about 750 before, and I stopped playing with at 650 or so yesterday. Probably not critical, just wondering. Tks...

 

750 with the AC on and in drive(if auto)

edit, a little higher is better than a little lower

 

I like the manual trans trucks to idle at 850. Makes it real smoooooth.

Autos can't idle much faster than 750 because they want to drive away unless you stand on the brakes.

 

Got it idling at 800 and could not be happier with that spring. It seems to feel better shifting at a little higher rpm. It pushed 17psi boost and pulled hard all the way up to 90mph on the way in to work this morning. 4.10 gears. Amazing. It is also running higher boost at cruise now as well, 4-5 psi loafing along at 65mph. Is that due to getting the fuel pin oriented deeper?