Diesel World

P-PUMP CUM­MINS TIM­ING

12 DE­GREES OF TIM­ING TO 18 DE­GREES--HOW MUCH WILL WE GAIN?

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We hear it all the time, tim­ing makes power. But how much power? Well, there are a num­ber of vari­ables but it was a ques­tion we de­cided to try and an­swer with our pretty much stock 12v P-pump Cum­mins pro­ject Green Mon­ster. In our last in­stall­ment we had put in a set of Scheid Diesel 5x0.018-inch in­jec­tors and gained a whop­ping 117 horse­power on the dyno. Since we were driv­ing the turbo harder, boost also went from 19 pounds to 38 pounds which was part of our vast in­crease in power. To make the most of these new in­jec­tors though, we needed to add tim­ing.

In­jec­tion tim­ing in a diesel works very sim­i­lar to the tim­ing curve that you would find in a gaso­line en­gine. One of the main dif­fer­ences how­ever is that you can run a lot more tim

ing with boost in a diesel en­gine thanks to their di­rect in­jec­tion and ro­bust na­ture. The fac­tory sets tim­ing at 12 de­grees, which is fine for cold star­tups noise con­cerns and over­all power, but we wanted to tell the bal­ance a bit to­wards the power part of the equa­tion. This meant ramp­ing up the tim­ing well above our 12-de­gree start­ing point.

One of the main con­sid­er­a­tions when it came to set­ting tim­ing is that we were still on the stock 270,000-mile head gas­ket with fac­tory re-tight­ened head­bolts. We have run up to 30 de­grees on trucks with ARP 625 head studs and fire ringed head gas­kets but we would be lim­ited (for now) by our fac­tory parts. Many hot street trucks or folks that tow and want a lit­tle bet­ter mileage ought to go just a few de­grees over stock which is what we did. We felt that a 5 to 7 de­gree bump would be ad­e­quate, and in the end we de­cided to go from 12 de­grees up to 18 de­grees of tim­ing.

We had the folks at Brown’s Diesel help us in set­ting tim­ing the “cor­rect way” which is to use a dial gauge on the de­liv­ery valve holder. You’ll need the spec­i­fi­ca­tions of your pump (160hp, 180hp, or 215hp) but as long as you have that you should be good to go. The ac­tual process didn’t take that long, but it was good to have two peo­ple on the truck. We also marked one side of the crank po­si­tion sen­sor to see how far it moved for those who may not have a dial in­di­ca­tor. The ru­mor was that mov­ing the en­gine from one side of the crank sen­sor

pickup to the other with the pump gear off was worth about 10 de­grees, as it turned out, the In­ter­net was close, and it ac­tu­ally turned out to be closer to 12 de­grees.

Once on the dyno the truck was a lit­tle louder, but noth­ing that bad, and cold start and other driv­ing as­pects of the truck re­mained un­changed. It should be noted that we did have to ad­just the idle up which was per­formed at the back of the pump with a 19 mm wrench. On the dyno, we were quite pleased with the power game, as we picked up an ad­di­tional 30 horse­power over what we had made with just the in­jec­tors alone. The ad­di­tional tim­ing also ac­tu­ally made the boost drop from 38psi to 35psi so in an ap­ples to ap­ples com­par­i­son the ex­tra six de­grees of tim­ing may have been worth even more than 30 horse­power. With 400 in sight, our next move will to be to in­stall a lift pump from Power Driven Diesel to see if we can break the 400rwhp mark. As for now, we learned that even six de­grees will make quite a dif­fer­ence in power, and in our case was worth al­most 10 per­cent!

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 ??  ?? The tim­ing pin is re­moved, and will be re­in­stalled back­wards later in or­der to hold the pump at a set tim­ing. But for now we just needed to re­move it. If you’re wor­ried about break­ing the small plas­tic pin (which can hap­pen if you’re not care­ful) metal ones are avail­able from var­i­ous ven­dors.
The tim­ing pin is re­moved, and will be re­in­stalled back­wards later in or­der to hold the pump at a set tim­ing. But for now we just needed to re­move it. If you’re wor­ried about break­ing the small plas­tic pin (which can hap­pen if you’re not care­ful) metal ones are avail­able from var­i­ous ven­dors.
 ??  ?? Our first step of our tim­ing change in­volved re­mov­ing a 24mm cap and re­mov­ing a small plas­tic “bul­let” that is used to pin the pump so it won’t move. A small amount of oil will come out which is ok, since it will be re­plen­ished as soon as the truck is restarted.
Our first step of our tim­ing change in­volved re­mov­ing a 24mm cap and re­mov­ing a small plas­tic “bul­let” that is used to pin the pump so it won’t move. A small amount of oil will come out which is ok, since it will be re­plen­ished as soon as the truck is restarted.
 ??  ?? Mov­ing up to the top of the en­gine, we loos­ened the #1 in­jec­tion line from the clamps and bent it slightly in or­der to clear the pump’s de­liv­ery valve. If you don’t feel like bend­ing the line you can al­ways just re­move it.
Mov­ing up to the top of the en­gine, we loos­ened the #1 in­jec­tion line from the clamps and bent it slightly in or­der to clear the pump’s de­liv­ery valve. If you don’t feel like bend­ing the line you can al­ways just re­move it.
 ??  ?? Next we re­moved the back #6 valve cover so we could see the rocker arms and then turned the en­gine back­wards by the al­ter­na­tor to get close to TDC. With the valves on #6 on over­lap (the rock­ers are cross­ing each other ris­ing and fall­ing) #1 should be close to Top Dead Cen­ter (TDC) on the com­pres­sion stroke, which is where we’ll need it to check tim­ing.
Next we re­moved the back #6 valve cover so we could see the rocker arms and then turned the en­gine back­wards by the al­ter­na­tor to get close to TDC. With the valves on #6 on over­lap (the rock­ers are cross­ing each other ris­ing and fall­ing) #1 should be close to Top Dead Cen­ter (TDC) on the com­pres­sion stroke, which is where we’ll need it to check tim­ing.
 ??  ?? Next we used a spe­cialty de­liv­ery valve tool to re­move the de­liv­ery valve from the pump, which will come out in a num­ber of pieces. Don’t lose any of these! Or get them dirty.
Next we used a spe­cialty de­liv­ery valve tool to re­move the de­liv­ery valve from the pump, which will come out in a num­ber of pieces. Don’t lose any of these! Or get them dirty.
 ??  ?? Back up on the top of the pump, we put the dial in­di­ca­tor at a high num­ber and ro­tated the en­gine back­wards un­til the pointer stopped drop­ping. This meant the dial in­di­ca­tor is at the back of the pump cam lobe. From there, we ze­roed out the dial in­di­ca­tor at 0.0 to find tim­ing via plunger lift.
Back up on the top of the pump, we put the dial in­di­ca­tor at a high num­ber and ro­tated the en­gine back­wards un­til the pointer stopped drop­ping. This meant the dial in­di­ca­tor is at the back of the pump cam lobe. From there, we ze­roed out the dial in­di­ca­tor at 0.0 to find tim­ing via plunger lift.
 ??  ?? From 0.0 lift, we ro­tated the en­gine for­ward un­til it reached TDC, which was mea­sured at 5.6mm of lift, or about 12 de­grees. Since fac­tory tim­ing was listed at 12.5 deg on our truck, we knew we were very close to TDC.
From 0.0 lift, we ro­tated the en­gine for­ward un­til it reached TDC, which was mea­sured at 5.6mm of lift, or about 12 de­grees. Since fac­tory tim­ing was listed at 12.5 deg on our truck, we knew we were very close to TDC.
 ??  ?? We marked TDC on the bal­ancer on ei­ther side of the crank sen­sor with a screw­driver for fu­ture ref­er­ence, and to see how much the damper would turn when our pump was re-timed.
We marked TDC on the bal­ancer on ei­ther side of the crank sen­sor with a screw­driver for fu­ture ref­er­ence, and to see how much the damper would turn when our pump was re-timed.
 ??  ?? After we found TDC, the oil filler was taken off, which gave us ac­cess to the large tim­ing pump gear nut.
After we found TDC, the oil filler was taken off, which gave us ac­cess to the large tim­ing pump gear nut.
 ??  ?? Tech­ni­cian Erick Brown mounted a dial in­di­ca­tor on the pump that ex­tended down into the pump and mea­sures pump camshaft lift. This will be used to de­ter­mine tim­ing.
Tech­ni­cian Erick Brown mounted a dial in­di­ca­tor on the pump that ex­tended down into the pump and mea­sures pump camshaft lift. This will be used to de­ter­mine tim­ing.
 ??  ?? When we got close to TDC, we took the valve cover off the num­ber 6 cylin­der and had one me­chanic go un­der the truck and turn the en­gine slowly by the fly­wheel teeth un­til the rock­ers crossed over. This meant cylin­der num­ber one would be on the top of the com­pres­sion stroke. Other pop­u­lar meth­ods of find­ing tdc are push­ing on the tim­ing pin right be­low the in­jec­tion pump, or us­ing a dial in­di­ca­tor set to the pis­ton on the num­ber 1 in­jec­tor hole.
When we got close to TDC, we took the valve cover off the num­ber 6 cylin­der and had one me­chanic go un­der the truck and turn the en­gine slowly by the fly­wheel teeth un­til the rock­ers crossed over. This meant cylin­der num­ber one would be on the top of the com­pres­sion stroke. Other pop­u­lar meth­ods of find­ing tdc are push­ing on the tim­ing pin right be­low the in­jec­tion pump, or us­ing a dial in­di­ca­tor set to the pis­ton on the num­ber 1 in­jec­tor hole.
 ??  ?? With the pump now ad­vanced six de­grees, we tight­ened the gear back down to 20 lb-ft to seat the gear, then pulled the tim­ing pin, held the en­gine with the bar­ring tool, and tight­ened it to a fi­nal torque of 144 lb-ft.
With the pump now ad­vanced six de­grees, we tight­ened the gear back down to 20 lb-ft to seat the gear, then pulled the tim­ing pin, held the en­gine with the bar­ring tool, and tight­ened it to a fi­nal torque of 144 lb-ft.
 ??  ?? After the pump gear was in­stalled, we re­moved the dial in­di­ca­tor, and reat­tached the in­jec­tion pump line and en­gine in­take.
After the pump gear was in­stalled, we re­moved the dial in­di­ca­tor, and reat­tached the in­jec­tion pump line and en­gine in­take.
 ??  ?? Since we hadn’t in­stalled gauges yet, we in­stalled a cou­ple makeshift ones for fuel pres­sure and boost so we could gather some ac­cu­rate data.
Since we hadn’t in­stalled gauges yet, we in­stalled a cou­ple makeshift ones for fuel pres­sure and boost so we could gather some ac­cu­rate data.
 ??  ?? After pin­ning the pump, we turned the en­gine back to our TDC marks, so that the pump would now be timed at 18 de­grees of tim­ing.
After pin­ning the pump, we turned the en­gine back to our TDC marks, so that the pump would now be timed at 18 de­grees of tim­ing.
 ??  ?? We con­tin­ued mov­ing the pump to 6.8mm of lift, or ap­prox­i­mately 18 de­grees be­fore pin­ning the pump (with the plas­tic pin shown in the third photo) and then pulling the in­jec­tion pump gear with a gear puller. A bar­ring tool was used to se­cure the en­gine in place so the tim­ing pin wouldn’t break when the gear was bro­ken loose.
We con­tin­ued mov­ing the pump to 6.8mm of lift, or ap­prox­i­mately 18 de­grees be­fore pin­ning the pump (with the plas­tic pin shown in the third photo) and then pulling the in­jec­tion pump gear with a gear puller. A bar­ring tool was used to se­cure the en­gine in place so the tim­ing pin wouldn’t break when the gear was bro­ken loose.

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