If i remember correct BC487 is advanced 2 teeth and near the factory mark.

 

Hmm... Maybe ill move it up a tad and see what happens. Id like to get the pump so i have better access to the center stud/nut anyway. Thats a real pain to get to when the pumps pulled all of the way back because the ksb gets in the way.

Thanks for the help Archer.

If theres anyone more input on this id like to hear it also.

 

I see hes had it 2 teeth advanced. I saved his picture of the gears so i knew which way the gear was supposed be turned. Hopefully he will give his input, i dont have experience tuning these truck but id like to get it right.

 

How much more timing does the spacer provide again?

I'm pretty sure mine could use more. It runs out of gas at about 90 mph. It used to go way past that before my injection pump fiasco this winter.

 

I dont know if this is exactly how it would work out but...

Stock is 2.4mm and thats 6-8*

With the spacer its max is 6.4mm which mathematically would be 16-21*

I dont know how much of the added travel can be taken advantage of. The math is fairly easy to mess with but the true science behind the pump isnt my strong point.

 

I put the pump back so the stock marks are lined up, still with the 1 tooth advanced. It runs better than it did yesterday. It might a tad louder i think but the truck is defiantly more responsive. My boost is still around 40psi so that didnt change even with me rotating 1/4" from yesterday. It may build more boost under load, its a little wet out and the trucks blowing the tires off up to 70mph in 4th gear... ive never felt that before in this truck lol.

I think ill leave it where its at for now.

I read a couple of times now that 1 tooth is 5* of pump timing, not 10* like i thought. That would mean my truck would have been near stock pump timing yesterday. I dont know what to believe.

I dont even know where stock is because ive read it was 8* and ive read its 12.5*.

 

The higher boost (40psi vs. 36) along with the quieter, mellower engine sound indicates you ended up with less timing advance with the changes you made.

Effects of increased timing advance:

1. Sharper engine rattle
2. Decreased exhaust noise (may not be detectable by ear)
3. Sometimes decreased exhaust smoke
4. Increased NOx emissions (may be an issue for those with certain emissions requirements)
5. Increased cylinder pressures (may want to retorque your headbolts)
6. Lower peak boost numbers
7. Lower EGT
8. Usually better fuel mileage
9. Slightly better throttle response

The effects of retarding the injection timing are generally the reverse of the above. Note that the pump timing was intentionally retarded in the Dodge application vs. other Cummins B series applications due to NOx emissions requirements.

I've always heard that when you start getting to much timing advance then engine starts to have a really sharp rattle, like an old Mercedes engine. I didn't go that wild with timing advance on my 1992, I just moved the pump about 1/8" and left it. That's basically taking it back to the same advance that Cummins sets on the B in other applications.

Mike

 

That's exactly what im thinking... I think i was just a pube too far because my boost would drop dramatically and my engine bay was having rattle... almost like injector knock.

 

If there's 72 teeth on the gear, (which is what I've been told), and the pump is timed to meter fuel once every 720°, (2 turns of the crank for every 1 turn of the cam,) then 720° divided by 72 teeth = 10°. Unless my math is wrong!

 

that's the math i was going by but there must be another factor involved because if i had added 10* it doesnt seem like it...

 

See, this is what is driving me crazy. I have to be right on the edge or slightly past. If I put the timing spacer on everything from idle up goes to doo-doo. On Midnites list I can say yes to everything there (except for those I can't check of course).