Need some help

[jer1]

A little while after I bought my truck, I picked up a 366 spring because I'd heard they were a good upgrade. Before installing it I was talking to the po and he told me it already had one. After installing gauges, I cranked the pump up. I was able to max the fuel screw with no sign of runaway. With the screw in all of the way, it was a little slower returning to idle(would start decelerating as soon as I let off the pedal, but tach didn't move down as quick as it did a turn out) It would start to de-fuel at about 2900, which I had read was fairly common. Fast forward.....Two days ago I had to pull the pump apart to replace a weeping throttle shaft o-ring and bushing. I figured as long as I was in there, might as well throw in the new spring. The old one looked the same as the new one, but didn't have any number on it that I could see. Got it back together and went for a test run. Let off the throttle and the r's would hang for 4-5 sec. before dropping. Close to runaway, which I'd never experienced before. Had to back out the fuel screw 3/4 turn or so to fix this. Now it doesn't de-fuel till 3400, but seems to be lacking a bit of power. Also, if I gradually increase the throttle, it's good till 1600 rpm. Just a little more, and it climbs to 3200(maybe more, that's where I let off) Tried turning the fuel screw down more with same result. What's going on? Input appreciated, Jer

[Greenleaf]

Sounds like you are on track. You will need to bac k out the fuel screw more untill it returns to idle speed normally like it used to.

They will act "funny" at various RPM/throttle positions when there is an unbalance as you have discovered.

The new spring is obvious a bit tighter.

[jer1]

Thanks GL. Does backing out the fuel screw limit fuel period, or does the heavier spring make up for it? Would afc removal get more fuel flowing?

[Greenleaf]

The fuel screw sets the position of the tensioning lever. This adj. will effect the fuel rate across the power band.

Removal of the afc can effect the fuel rate. It would depend upon what other mods are performed as well as what is done to the afc function.

[jer1]

Would slightly lengthening the spring allow me to crank up the fuel screw to where it used to be and keep the high speed effect? As far as the afc goes, I was thinking about removing the lever. I read a thread a while back by you about driving the bearings out, removing the lever, and sealing things up with epoxy. Can't remember where it was, but that was the gist of it. I don't have to pass emissions, and don't mind using the right foot for smoke control. More fuel=better

[Greenleaf]

I would opt to keep the current spring and back the fuel control screw out. I have one of mine set with no AFC and the 366 spring. The fuel control screw is backed oiut about one turn more tham needed and I still cannot control egt's with the current engine/turbo mods.

I have another pump that is et to run-a-way. I juts don't allow it to. For example; don't rev the engine in neutral.

There you have two different examples. Both trucks have more power than I could ever use/need and the smoke is uncontrollable with foot-feed applications

[jer1]

Thank you much. How high should the 366 spring allow the truck to rev? I've taken it up to 3800, where I let off. Sounded like too many r's to me. But I'm not used to hearing it above 3200, where it would stop before.

[Greenleaf]

The 92 goes to 4,000. I have yet to push it past that. Valve springs are 60#

I don't know about the other. It has no tach. I simply use my ear to gauge the rpm's