okay so I helped my brother time his truck today......'95 3500. CPL sais 1957. Pretty straight forward and I set him up to 16.5*. We pulled my truck in to double check the timing on it as well. Initially, several months ago, I set it up 17* per the piers lift chart for cpl 1968. After the tweak, I noticed none of the traits usually associated with that much of a timing increase. I looked in my DC manual for specs and found no different cpl's....merely auto or standard specs. The I noticed the manual trans specs matched cpl 1968 only 160 hp pumps per piers chart. The auto specs matched the "all others BUT 1968 cpl 160 hp pumps" per piers. So which would a guy believe?? The DC specs or piers? If I were to set mine to auto specs at 17* per the DC manual and I should've used piers for the 1968 cpl...then the timing would be somewhere around 23.5* using the lift number in the DC manual. If I set it at 17* per piers 1968, and It should be per DC manual, the timing would be less than 10?

The monkey wrench is this.......ordinarily I would use the piers 1968 specs, but there is evidence that this pump may be changed. paint missing from bolts and nuts, etc...etc. I also noticed it had 167(?) DV's, whereas my bros had 131's. I decided to dial it in using the DC manual auto specs with 6.5 mm lift setting, rather than the 5.1 mm piers setting. I fired it up, epecting it to blow....or not start at all, and voila....first crank it lit and number one bled easily and it smoothed out in no time. idle rattle was markedly noisier, though not "extreme". All sounded okay so out on a hot lap I went. Great power....not much low end loss, and a lot smoother mid and top. EGT's dropped 100* as well.

So my question is this......why is the 1968 cpl a card all of its own, and why does it have 167 DV's, when several other '95's I know of have the "all others" 160 hp pump with 131 DV's. And why are the timing specs so different? One other perculiarality I have noticed is most trucks in '95 that I have seen use the "across the valve cover" wastegate pressure line. Mine has a short hose from the gate to the compressor outlet. What do you guys think?? I left it at 17* i.e. 6.5 mm lift per DC manual extrapulation. Either it'll be allright....or I'll be getting that o ring job sooner than the wife thinks

Thanks...Chris

 

I have heard of the CPL 1968 pump having different specs as far as setup goes - don't know if it has different height plungers or what........I would believe the Peirs chart.......AS far as DV's go, I too was under the impression that all 160hp pumps had 131's but maybe that is the one of the differences with the #1968.........I guess it is a bonus to have the 167's but I would be willing to bet if those are the original DV's for that pump, then it is not the original 160 pump on that motor........I think you need to get to a Cummins dealer with some #'s off the pump and the CPL#........they will be able to tell you if the pump # matches up to what the CPL plate indicates should be on that motor.......

 

When I was reading about adding 370s to a 160 pump they were saying that some 160s has 131dvs and some have bigger dvs. I know also that the early 95s had the wh1c turbo and the later ones have hx35 so that might explain the different waste gate hose.i had both but never checked the dvs.

 

definitely have the HX35. Some have told me that the differences in my truck might be canadian or californian, tho I don't have an EGR either. I'll scrutinize he pump and try to pull some Bosch numbers to narrow down its vintage, or if is indeed the stock pump.

As a side note, it was 13 degrees when I got up this morning. I didn't plug the truck in last night because I wanted to see how it started. I didn't even allow the heat cycle and it lit on the 2nd crank from a 13 degree cold start. Now maybe all you timing gurus can enlighten me, or correct me, but if I was indeed sitting on top of 23.5 degrees of timing, shouldn't this thing have been a bear to start? There was no smoke at idle either, ran like it always does, warmed up in 20 minutes and I was off and running. Knock was a little more noticeable at idle in gear, but again, nothing extreme. Hmmm........

I'll be sure to crunch some numbers though just to be sure of which pump lift numbers to use. Any more comments are welcome in the meantime, and I'll let you all know what I find out.

One more thing. I was putting off injectors until I got some different DV's. I should be thinking turbo as well, but have no EGT issues and she burns clean. Way I figure it, I got a little more room for fuel. Now that I know I have these wildcard 167 DV's, I was considering a 300 or 370 injector.......until I can swing a set of aftermarkets. I have a set of each being given to me from a couple of low hour marine motors out of two salvaged boats. What do you think? Worth the time to change 'em and try 'em out?

How did your pump respond to the 215 Dufrain, and do you have the 131's?

CTD NUT......do you still have the small pump in your '94? And did you just do DV's or injectors too? Which ones, and how did you like them?

Thanks,

Chris

 

Im not sure which dvs I have so I just went with the 215s.The 215s were the difference in slipping the clutch and not.It never slipped before i added them.Its not a huge difference but its a nice increase and not much smoke but it puffs a good pile out when you step on it.Most guys say skip the 300s and go to the 370s.From what I read I think you could get by withyour dvs and the 370s since you have the larger ones but with that 100 plate your going to have alot of heat .I dont think it would tow very good but may be nice for hot rodding,but I bet youll have to add a ex housing and maybe a bigger wheel.

The more retarded the timing is the easier it is to start so I bet your truck isnt at 23.5 starting that easy at that temp sounds more like 13.5.My 95 truck with stock timing started 10 times easier than my current truck with 16 degrees supposedly.Its been changed but not by me so I dont know what it really is just going by what they told me.Mine did start last week at 10 or so degrees without much trouble but it gelled up on me and died.I didnt have any additive in there

 

If you could find a diesel shop with a diesel timing light that might help you out to see what its actually set to

 

That's a good idea too.....I spent hours with a dial indicator to find the perfect TDC and marked it with a nice pointer and degree tape. A timing light would tell the tale.

I agree with you, set at 6.5 mm TDC, I believe the timing CANNOT be what the piers table shows for a 1968 CPL.....extrapulated out to 24*!! It almost HAS to be 17* as the DC specs for auto tranny dictate. It just doesn't run like it is that far advanced, nor sound like it.

Strangely enough, I also noticed ALOT more off idle snap. I expected to see less low end, as advanced timing usually causes, but not this one. My pre-boost smoke was none, as before it was light to moderate. I actually dialed out the star wheel some more to compensate, and wow, that even made it better. Before there was a noticeable "lag" before the power come on. Now it is almost seemless with no noticeable lag at all, and preboost smoke is still negligable. Overall I am very happy with how it is running as tuned. Of course, the next step is right around the corner

As usual, thanks, and I will give you some updates as I find them about the pump mystery.

Chris

 

From what you are describing, I would tend to think the timing is not at 23.5 degrees.........FWIW, I have not noticed these decreaeses in bottom end power that others claim when the timing is advanced - I noticed no loss of bottom end when going to 17 degrees but I later dropped it down to 16 because the truck was used to tow heavy from time to time and I had some high cylinder pressure concerns............I still have the 160 pump with 191 dv's, which by the way, pushed bottom end power through the roof........the big dv's didn't help much on the top end because of the stock injector but, like you, I have a cheap set of the 370's on the way............IMO, I wouldn't worry about the 160 pump.......it should provide tons of fuel with 370's and 191 dv's - the turbo will be the problem - I was hesitant to step up to the 370's because I don't think I have enough turbo but we will see .........I'm very interested in hearing how you make out with your pump mystery......

 

Thanks for the come back CTD........Yes, my turbo is on numbered weeks....or months. I have been running it at 34 psi for nearly a year and can't believe the extra rpm isn't detrimental to its lifespan! So far the mods have been cheap......'cept for the trans of course......and I believe I will throw them injectors in and see what the heat does. Before timing, at 90 mph OD full throttle I would have to get out of it due to 1300*. I tried again and at 90 mph EGT's are way down to 1000*. I didn't want to go any faster though to see where she topped out at. I think, based on this, I will throw in the injectors on the 167's and see what happens. Nothing ventured nothing gained right? If it's too hot, I'll either back off the 100 or let the skinny pedal be the thermostat for a while till I can stuff some more air into the holes.

I'll let you know.....I do know I sure like the 100 plate so far.....noticed you're running one also

Chris

 

34 psi!

That's low, I can hit that in valet mode. You're charger will live a LONG life at those speeds.

I put in my new clutch this weekend (finally ) and now I'm hitting 43psi, before it was 39-40 MAX. Pyro is also pegged, too.

I need a charger bad, then I'll go with some DV's, then bigger fire sticks!

needasupportgroup,
Chris

 

Oh yeah, don't get me wrong, I can stab 40+ as well, but I have it turned back because I've been told by many that after 36 psi, it's just hot air, and overspeeding as well. At this point in the build, I don't see too much smoke yet, and EGT's are manageable, so I figure boost is adequate. After I stoke it up a little and see too much smoke or heat, I might crank it up a little more and order up that modified huffer I've been eyeballing I assume you just block your gate right?

 

I have been down that road. There is two different timing charts for the 95. I ran the wrong one for a couple of a years and the truck did not seem the start different. I did like the way the truck run. How ever the idea of lifting a head gasket did not appeal to me. When I found out about the different CPL I did change to the timing of 17.5 from a lot more
The injectors washer thickness can have a effect on how the truck starts and may be a benefit to those who run advanced timing. If Piers told me some thing I would believe Him, regards jim

 

Yeah, I think anything above 35-36 starts getting hotter. If I keep the boost ~35, EGT's will hove ~1250*, then I can push the throttle a little farther and EGT's are Pegged!!

Chris