Engine/Transmission (1994 - 1998) Pump timing ?

[TRAMPLINEMAN]

Ok, I've read countless posts on how to adjust the timing, but I can't find how to determine where to set it. My truck is not stock so I'm thinking the stock setting would not be the optimal setting!? I recently removed the twin turbo setup and am back to single status. How does one go about determining where the timing should be set on a modified truck?

 

[Missouri Mule]

I read 15. 5 to 16 degrees before TDC for street use(stock is around 13 degrees before TDC), but depends how modified the truck is.

 

[TRAMPLINEMAN]

Thanks. It's been so long since I had it done, but 17* before I installed twins keeps popping in my head.

 

[GAmes]

The one downside of a 12 valve is the timing is only optimum in one small RPM range. Unlike newer diesels that change injector timing according to several parameters, you are stuck with only one. So what speed do you drive normally? If it is mostly in town and less than 50 mph the stock timing is about as good as it gets. If you routinely drive 75 for several hours at a time then 16 or possibly even more would help your mileage. Be aware that the higher you set the timing the slower the turbo spools up when taking off from a dead stop. Most of my driving is in the 1900 to 2200 rpm range. I have found, by experimenting with several settings, that 15 degrees works the best for my gearing and loads. Buy a set of tools and do a little experimenting of your own.

 

[TRAMPLINEMAN]

GAmes, thank you. I normally drive 73 everywhere on the highway. But, I've decided to sell the truck. It's not an easy decision, but the truck sits in the garage and is only driven 200-300 miles a year. I just want to get it set so the next owner will be happy with it.

 

[GAmes]

In that case I would set it between 14. 5 and 15. That way there will be pretty good acceleration when the potential buyer test drives it.

 

[BSMcCauley]

The "correct" timing will be printed on the data tag on the timing gearcase. On my '96, it's 13° BTDC. As noted earlier, running around town at low RPM's that's probably going to be fine. At highway speed, more is better, but I've been cautioned that high strength head bolts are advised if you go much past 16°. I've got mine set just over 15°. I've got a couple minor mods, but don't have any problem with turbo lag on the factory turbo.

 

[jerseyboy]

just clarifying, 0* timing would be an injection when the cylinder is at TDC? and advanced timing is injecting before TDC

 

[CKelley1]

yes it is 15. 5* btdc

 

[jerseyboy]

right on, thank you sir

 

[TRAMPLINEMAN]

Another question, say I tell the mechanic(who's Cummins certified) that I want it set at 15*. How long should it take a certified Cummins mechanic to do this job?

 

[jerseyboy]

one who knows what he is doing, under an hour

 

[TRAMPLINEMAN]

That's what I thought. Thank you.

 

[jerseyboy]

these are great videos, not mine though
12 valve Cummins timing in 40 minutes part 1. mp4 - YouTube

 

[TRAMPLINEMAN]

That's a good video. A few years ago I watched Richard Brown of Browns Diesel set my timing in about 45 minutes. Yesterday I was quoted 4 hours at $120 an hour at Cummins in Wausau, WI. Go **** yourself! I found a shop an hour and a half away that will do it in an hour for $80.

 

[jerseyboy]

yeah it helped me reset mine after i slipped it! but wow, shops annoy me sometime. but its great to have a good honest guy to go to. the $80 sounds perfect for the job

 

[ewcmr2]

When bringing it to a shop make sure they are going to set timing where you want it. After calling a Bosch shop, asking the price to set timing to 15*, and driving my truck to them they looked at me like I was from outer space when I confirmed I wanted timing @ 15*.

Service writer: "we just set it to factory spec with the blade in the pump"
Me: "Thanks for mentioning that you wont do what I asked for on the phone, I'd like my keys back now"

I drive home and ordered the P7100 timing kit.

 

[LVJUNIOR]

If you have head studs and fire rings is 18° too much at 2200rpm

 

[Joseph Donnelly]

See TDR Issue 61, p. 102 for a discussion of timing settings and procedures. For around 2000 rpm, 15. 5 degrees seems to work well.

 

[Joseph Donnelly]

No, 18 degrees is OK, but may be a degree or two higher than optimum for that rpm.