I've only got 1 turn on my starwheel and have read about people going "5-6 turns from bottoming out". This made me realize the starwheel must go a lot further than I have it. Does anyone know the approximate maximum amount of CW turns the starwheel will go?

I also read about backing the smoke screw out all the way after cranking down the starwheel (to help get rid of excess smoke). The smoke screw was one of my first pump tweaks and it seemed to help the throttle response tremendously. If I crank the starwheel down and back the smoke screw out will I lose any of the improvements I originally got just from the smoke screw?

 

what is a smoke screw and where is it

 

You can run the pump without the starwheel if you wish. It creates lots of smoke if that's your thing. I actually run mine UP from stock a couple of turns with the smoke screw backed all the way out, the full power screw in a 2 turns, and the AFC cone turned to its maximum depth. This gives me good power at full boost, decent response (due to a smaller exhaust housing), and very little smoke.

 

The T-25 Torx head screw with a 13mm jamnut on top of the AFC housing. It is concealed by a thin metal cap that can be pryed out with a couple of thin blade screwdrivers. Turning it 2 turns CW really helped response and driveability on the stock truck.

 

I don't get it. At just a few clicks over 1 turn CW, my starwheel seemed to tighten up and acted like it was bottomed out.

I shaved the washer and moved my fuel pin to it's deepest setting. Also backed the smoke screw out another 1/2 turn (so it's in 1/2 turn CW from stock). With these new changes I seem to have lost 1/2-1psi of max boost. Could that be due to our ouside temp being 95* instead of 75*?

 

How many threads are sticking out in the middle of the starwheel? If it's bottomed, there'll be 4-5 threads showing. There are a couple metal 'tangs' that ride on the outside of the starwheel---they engage the starwheel to keep it from moving from where it's set. When running mine down once, I got one of those tangs caught under the starwheel and that limited my movement..you might want to check for that. The smoke screw is compleetly out of the picture once you're off idle. Period. It won't affect max boost, regardless of the setting. Be sure the deep part of the cone is facing the radiator, and be sure the guide pin that rides on the cone is indeed popping out when the throttle is cycled. A little di-electric grease sometimes helps here. If you cycle the throttle with the cone out to verify pin movement, just remember to pry the pin back flush with the housing before you replace the cone. Outside temps will definitely have an affect on boost numbers and overall performance.
greg

 

Thanks Greg.

That info helped a lot because it was bottomed out after only 1 turn and about 3-4 clicks more. Nothing else was touched on this truck and it came from an 83yo original owner, so I assumed the starwheel was factory set still. Anyone ever seen or heard of a starwheel being 1 turn away from maxed out from the factory?

The only other sign of tampering on this truck was the fuel pin. It had a very pronounced wear mark on the stock setting when I first opened it up. It also had another much lighter wear mark about 45* to one side. AFAIK this truck was always serviced at the local dealership (even until this past March right before the PO passed away). Would the dealer service department have messed around with the AFC to get him some more power or response if he complained or the truck seemed slow when new from the factory? Would the service dept even mess with the AFC for this reason?

 

The factory setup of these pumps varies widely...VERY widely. The pumps themselves are not all created equal. Two identical trucks with identical settings will respond completely differently to, for example, a set of injectors. Use others' experience/dyno #'s only as a guideline, as your personal truck will likely stray from any 'norm'. These old girls are very organic when compared to the newer rigs---it's part of the charm. As for the AFC settings, it's possible the dealer had a diesel-savvy tech that did a little pump fiddling. Perhaps the previous owner just got curoius. Or, it could've been set that way from the factory, but since there are two marks on the cone, someone was definitely in there before you.

 

Tucker, how much max boost are you pushing with your setup?

Also, pretty sure I figured out where my 1/2-1psi of lost boost went. I had the A/C on when I took that reading and it was also 95* outside.

 

Just curious....I did all my starwheel, smoke screw and smokey pin tweaks to my pump about 5 months ago. It never occured to me to check cycling of the guide pin to make sure it rides the smokey pin. What would happen if I did this incorectly? could there possibly be a way that the smokey pin is accidentally "on top" of the guide pin?

 

If the guide pin was extended into the housing, the old smokey pin wouldn't fit in, so I think you're good there. If the guide pin is sticking, you would definitely feel the lack of power under boost. It's easy enough to test--just pull the smokey pin and cycle the throttle.