You can't say that the p7100 has variable timing. It is set static across the rpm range. The 913 pump can change very slightly depending on rack travel and barrel rotation, but isn't considered variable. Bosch has a few good texts discussing their injection pumps. They can be found on their web site. Pretty good read to explain how the plunger/barrels really work to delivery fuel and how the helix and rotation of the barrels controls how much. The charts are overwhelming for me, but the basics helped.

 

Yup. The 913 is the only p-pump that I've ever head of that has variable timing. Only Piers's stupid pump can move more fuel, but it has completely fixed timing like all the others.

 

Why can't I say that it has variable timing? You are right in that the timing doesn't change with rpm, but it does change with rack position because it has sort of a double helix.

I don't know this for sure, but I believe that this was done for emissions purposes. Retarding the timing helps with reducing NOx emissions. This pump has the advantages of advanced timing for light throttle, but then retards the timing before the NOx gets out of hand. That's just a guess, but I can't think of any other reason for doing this. The fact that the timing gets retarded as the rack moves (towards full throttle) is not a guess though.

 

Extreme D:

I think we are both saying similar things and it may be more semantics on my part. When I say it's not variable I meant in comparison to the VP44 and the after market timing boxes - those are truly variable. The 913 can "vary" the timing slightly with rack travel, but the amount that it can do it is not variable. I think this is what you meant when you say variable? I don't think the timing change is due to the helix as this is the basic design behind all Ppumps. It has more to due with the shape of the top of the plunger being "dished" out in the center.

 

Good explanation, earlier in the thread, Paul - thanks.

Guess I'll mosey on over to the Bosch site for the detail

 

I tried to find the link for the Bosch books on their site but couldn't. I remember I ordered mine from Barnes & Noble. Here is a link with the Bosch Technical books from B&N. The second one is a good one for detailed explanation B&N Bosch Tech book list

 

Yeah, I think we're on the same page now Paul.

 

Very helpful, thanks again, Paul.

I've been searching for more than 6 years now for similar info pertaining to the Stanadyne DS4 EFI pump, but it would appear that they are too ashamed of it to write about it.

Buh - mer ! !

 

Thanks for the discussion on P pumps. This site is the best for getting what seems at times to be "top secret" information.

 

Draggin' this back to the top - is #887 the 180hp or the 215hp P7100?

The engine was changed before I got the truck, and the CPL plate was ripped off - I'm sorta suspectin' that was done to conceal an automatic engine put in a manual trans truck.

The IP # is 0 402 736 887

Hit me with the hard facts, folks.....don't pull no punches.....I'm tough.....I can take it..................

I

 

You have a 215 pump. The 887 and 913 are both 215 pumps.

 

Thanks, he said, with a sigh of relief.............

Any way to tell, from all those numbers on that Bosch tag, an approximate date of manufacture?

3485 would be Julian date for Dec 05

1205 or 0512 would be Dec 05

4905 or 0549 would be Dec 05

There are even more, but no need to belabor the point, eh?

 

Payback time, folks - FYI spec #885 is definitely a 180hp P7100

And, looks like the first digit of the serial number may be the year of manufacture