timing adjustment 12 valve - Diesel Bombers

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timing adjustment 12 valve


Old 03-19-2009, 11:51 AM
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Default timing adjustment 12 valve

i just chopped my fuel plate down to a #100 and have my starwheel all the way forward.. people have been telling me i need to change my timing cuz when i get on it from 0mph it is shifting really hard until it gets into overdrive then it has no trouble picking up speed. any suggestions on if i need to change my timing and if so how do you do that, is it hard?
Old 03-19-2009, 12:31 PM
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How to adjust the pump timing on the P7100 pump.

First let me say that VERY LITTLE of this information originates from me. It has all been gleaned from various posts and other web sites. A good chunk is from our faithful helper/friend Joseph Donnelly.

Is this the ONLY way to adjust it - NO! But it seems to be the most common.

First you are going to need tools! Besides your normal hand tools you will need the following special tools for the P7100 pump. You can get these from Snap-on or from Miller. Each tool set is a little different, but it will do the same thing. Get the one that seems best for you - ex: If you already have a barring tool, you will get another one if you buy the Miller tool set.

Snap-on set is part number SP500.

Miller set is SPX MILLER #6860.
SPX Miller Special Tools | Main

Various parts you may/will need:
Delivery Valve Washer
Mopar number 4778483 or 4874514
Bosch - 2 410 101 014

delivery valve o-ring
Bosch number 2 410 210 033

Pump gear lock washer
Mopar number 4761314
Cummins - 3920922

timing pin (TDC pin)
Cummins 3903924

timing pin o-ring
Cummins 3913994

What are the pros / cons of adjusting the timing?

There is a TSB on how to adjust injection pump timing - this I found at:
TSB 18-10-94 Rev. A

There are 2 places for charts on the pump timing. You will notice that there is a slight discrepancy on the number for the amount of lift. Don't worry about it - you will not be that accurate anyhow.
Diesel Timing

A problem that will may run into is "My TDC pin is broken off."
There are several ways to find TDC - do a search and you will see. An easy way is as described by Joseph Donnelly:

"Find the approximate TDC where the valves for #1 are not moving. The #6 valves will be moving. using the alternator is not real good because the gear lash is taken up the wrong direction. Use the barring tool and rotate the engine in the direction it runs. this will be counterclockwise on the barring tool handle and clockwise on the harmonic balancer. #6 exhaust will be almost closed, and #6 intake just opening.

Put a piece of masking tape on the balancer underneath the truck, and affix a pointer made of wire under an oil pan bolt, running to the tape.

Go back on top. Remove #1 valve cover and use the KD spring compressor to compress #1 exhaust valve spring. Now the valve will rest on the piston, about 0.090" down the hole. Put on a magnetic base dial indicator to the top of the spring compressor handle/stalk. As you rotate the engine, you will see a reading where the valve is up at its highest position, corresponding to TDC. Lets say that is 50 on the indicator. Rotate the engine backwards to say 30, and then start rotating forward to say 35.

Go under the truck and make a sharp line where the pointer is on the tape.

Go back on top and rotate the engine forward past 50 until the reading drops back to 35.

Go under the truck and make a second mark (sharp line) where the wire pointer is on the tape. Using vernier calipers, measure the distance between the sharp lines you made. Exactly the center between these marks is TDC when rotating the engine in forward direction (clockwise on the balancer looking at the front of the engine).

If you do a very careful job, this is as good or better than using the timing pin."

After finding TDC I also made a mark by the crank sensor - that way I could see it from the top.

If you do a search you will notice that various people recommend different torque specs for the pump gear nut - from ma Mopar's original 122 ft lb - that was bumped to 144 ft lbs. Then we have Joe G and others stating you should go to 165 ft lbs. What is the best?.

The gear and shaft must be clean! Joseph Donnelly recommends the following for installing the pump gear:

"Use Mopar 4897150AB brake cleaner to clean the taper on the pump shaft and in the gear. Most parts house cleaners have heavy hydrocarbons that don't evaporate well and leave residues. Behind the gear is the approx. 4.25" diameter by 15/16" deep hole in the gear housing for the pump nose (front bearing retainer). However, there is a “trough” remaining at the bottom because the pump nose doesn't end up flush (it's only about 7/16" thick). The trough therefore ends up about 1/2" deep. It accumulates engine oil, and will also accumulate the spray cleaner. The force of the sprayed cleaner then kicks up this oil and solvent back onto the taper you are trying to clean. Additionally, the bearing at the front of the pump shaft, right behind the taper, is a non-sealed bearing. It drains oil back to the crankcase, and also can contaminate the taper. When you spray excessively or blow dry real hard, you may be kicking up some of the oil from this bearing. In summary, use light spraying pressure with the cleaner solvent, and a light air pressure to blow dry the taper surfaces. I use the cleaner a couple times, with the last time being just before pushing the gear onto the tapered shaft. I also thread a long bolt into the gear so I can wiggle it and be sure all parts of the taper get cleaned. I blow dry carefully, again, not with real high flow/pressure.

Push the gear into place. Don't rely on the nut to pull it onto the taper. Leave the oil on the nut and washer because you have washed all the oil off the threads on the pump shaft. You need just the film of oil on the washer and nut to lubricate the threads.

DON'T use over 150 ft lb on the pump shaft nut. The threads were torn off on the $800 215 hp shaft by someone I know who used a torque of 175 ft lb. Then you have $500 to R&R the shaft. If the taper is clean and dry, you'd be surprised how few ft lb are really needed. If not clean and dry, you can't get it tight enough to hold. If there is a bur on the shaft, it won’t hold."
The Following User Says Thank You to Whit For This Useful Post:
95 12 valver (03-22-2009)
Old 03-19-2009, 05:39 PM
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thanks for the info, but i might wait awhile before i do that it looks pretty hard
Old 03-30-2009, 11:09 AM
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I have a 98 12 valve with full cut industrial injection dilivery valves, 370 marine injectors, (I know they are not the best but they were cheap) with #6 fuel plate and 3000 spring kit, and phat shaft 62, needless to say, lots of fuel. I had industrial try and advance the pump, well they couldnt. they do it all the time but they couldnt break the bolt loose, so all of this with stock timing (about 14 degrees) should be 20. mine pops and wont throttle up well with no load. get an actual fuel plate or turn it down a wi bit. I think it will help. it helps mine
Old 03-31-2009, 12:54 AM
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ehhh sounds like a bitch,, hope my truck runs good with the 100 plate, i don't really want to change the timming just yet...im still a nube
Old 03-31-2009, 10:05 AM
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Timing could help but I think your putting the fire out down low. Try cranking back on that starwheel a little. Whats your EGTs? Is your AFC at full forward?

Timing is really easy. You just need a timing kit.
Old 04-08-2009, 01:25 PM
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my EGTs are peaking out at 1100 degrees, ok xzag103 i sent you a PM
Old 06-17-2009, 09:37 AM
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im takin my truck to a diesel shop and havin it set at 16 in like a hour. its goin to be like 260
Old 06-17-2009, 09:44 AM
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It would be cheaper to buy the tools.
Old 06-17-2009, 10:33 AM
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ya dont take it someone that is going to charge you $260 thats just stupid
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