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P-pump conversion

55K views 39 replies 22 participants last post by  ash_flat_diesel 
#1 ·
what's involved?

I read on the 1st gen dodges you need to replace the whole timing case. Kinda seems it would be easier to just grab an originally p-pumped engine if that were true.

Anyone got any good info on this?
 
#4 ·
After looking at the part numbers for the timing set, I only see that the cam is different from the naturally aspirated 4b to the turbo and turbo/aftercooled models. The crankshaft gear and cam gear are the same for the ve and p pump models. The gear for the p pump is different than the ve pump. I think all you need is a p pump with gear. Obviously the injector lines and injectors are different as well.
 
#8 ·
like i said everything is special for a p-pump engine, cam, cam gear, timming cover, fuel pump, pump supports, fuel lines, lift pump, big $$$$$$$$ to change it correctly. the difference between the two pumps mainly is the p-pump has 4 pistons inside to pump fuel to there respective cylinders, the ve pump has a central ( common ) pump with fuel distributed in a rotary vane manner. when you try to max out the fuel system in a ve pump after you reach a certain point the idle will go up also. it gets to where the rotary vane cant control the fuel delivery properly . dont worry though the ve pump will supply enough fuel to do a real good job burnning the pistons litterally out of your engine. YOUR ALOT BETTER OFF STICKING TO A CPL ENGINE CODE
IMO.
BOB
 
#9 ·
there was never a p-pump on the 4bt. not that it is really relevant but the inline on the 4b is an "a" not a p pump. not being a smart ass. just thought i would let you know. and besides reliabilitly it is capeable of a lot more than a ve if you are going all out. you can get a ve to push alot of fuel with the right mods. until you get extreme it is hard to justify the cost of the swap. I have seen a ve in a 6b make 500hp, just takes a little know how.
 
#10 ·
there was never a p-pump on the 4bt. not that it is really relevant but the inline on the 4b is an "a" not a p pump. not being a smart ass. just thought i would let you know. and besides reliability it is capable of a lot more than a ve if you are going all out. you can get a ve to push alot of fuel with the right mods. until you get extreme it is hard to justify the cost of the swap. I have seen a ve in a 6b make 500hp, just takes a little know how.
well just to let you know i have a p-7100 pumped 4bt all stock 130hp cpl#1839.
it is just like the one on eBay item #160089417899
i also have 2 "a" pumped 4bts also
 
#11 ·
The a pumps have 4 bolts on the timing cover and the VE has three. So you need to swap timing covers regardless even if you were to use the VE cam etc.. I am with Bob on this, not worth the effort IMO when a VE pump can/will work fine, I think.. For a race car though maybe the inline is better. Lou Chou one of the original swappers had a inline pump on his 4BT, and there is a FJ55 rock crawler out there called "big stinky" that hte owner had something like $10G into with an inline pump that was all juiced up and loud as all hell, much more so than stock because of the fuel levels at idle. Pretty sure the 7100 pumped inlines use the same torque plate etc as the '94 and on 12 valve dodges..

I also have a inline 4BT A pump lying around. We were considering swapping into a truck regardless to see how it does. Supposedly the throttle response mechanism of the a pumps can be detuned to give a more typically automotive feel, I have been told..
 
#15 ·
Yeah I just got through drooling over one. P7100 pump with air to water. They are super hard to find. Ive been dealing with the VE's forever and know some guys pushing some serious numbers with them. I like em, the are readily available for us, cheaper, and they are found on light line stuff and ag stuff. Easy to work on too. Its a 4bt though, most of us are doing this conversion for fuel, efficiency and longevity, the VE will handle that anyday.
 
#18 ·
Do the cummins inline pumps have aneroids fitted?

I pulled the aneroid on my pump apart and found the diaphragm in it was shot. That'll account for the on/off torque surge I've been getting.

Easy check if you've got one, pull the line to the aneroid off the intake and blow down it. If it leaks it needs attention.
 
#20 ·
Just to ad my $.02...The P pump, or the A pump, are almost required if you want to run alt. fuel; straight veg oil, etc. I've found they handle it much better.
Nah, buddy of mine has been running straight veggie and bio for years on the VE. Had to replace the lift pump once, but we all have to do that ever so often.
 
#22 ·
I see straight veg running through VE's on cummins trucks at my shop daily. As long as the oil is clean and heated properly, they hold up well. If not, well....
You can however slack on that a little with the inline pumps as they seem to take the abuse a bit better. But then again, they are more expensive to rebuild.
 
#23 ·
Correct me if i am wrong but the A pump and P pump motors share a timing cover and gear set?

If that is the case then a P pump conversion to an "A" pumped motor should be possible also for those looking to do a P-pump conversion.

Doubt the fuel lines interchange and maybe someone can shed some light on the other particulars but the a pump motors that are being drilled and scrapped in CA would be a place to start potentially sourcing timing gear sets and timing covers for this swap cheaply.... like in free in some cases
 
#34 ·
So, I have no experience with the 4bta, but I am half decently experienced with the 6 cylinder version, and much of that knowledge should interchange.

Timing case, get one for a p-pumped 12v.

Injection lines. Use the first four from that 12v.

Cam. No need to change that, as it really has nothing to do with the pump other than acting as an idler gear. Thats a common myth when p-pumping a 24v too.

P-pumps have no timing advance, but is that really an issue? If you're looking for big fuel, then losing some advance isn't much of an issue. There have been 500+ hp on a VE in a 12v, but that is running a 14mm head. P-pumps are able to do that, often without any changes other than timing, injectors plate and governor springs.
 
#35 ·
Forgive me guys for re-writing a Bosch manual, or sounding condescending, but here's the big difference with the whole timing issue.

First, the faster the engine is running, the less time there is to get the fuel burned before the exhaust stroke starts. So as the engine speed increases, the timing should increase to maintain max power.

The VE pump does this by means of a piston connected to the roller ring. As supply pump pressure increases with speed, the piston is moved against a spring, rotating the roller ring and therefore advancing the start of injection, or PORT CLOSURE. Remember that term, there's a test later.:grinpimp:

The KSB (German acronym for cold start advance) does it by jacking up the pressure to the timing piston when the engine is cold.

On the P and A pumps, the timing is fixed due to the HELIX of the pumping plunger. Bear with me on this one. The in lines have plungers and barrels (P&B's) that pressurise the fuel. The barrels have what's called a fill/spill port. This is where the fuel enters the P&B to get pushed on to the injectors. The Plunger doesn't start pumping until it rises high enough to close this port. This event is referred to as PORT CLOSURE. Kind of like the way a two stroke engine runs. Now, we need a way to limit the amount of fuel delivered per stroke. Enter THE HELIX. The Helix is nothing more than a Helical cut from the head of the plunger partially down the plunger. Think barber pole. So, if we rotate the plunger within the barrel, we change the orientation of the helix to the fill/spill port. If we want max fuel, we keep the helix away from the port as long as possible to get the max fuel. For Idling, we simply rotate the plunger the other way, thereby moving the helix closer to the port. As soon as the helix starts to pass the port, all of the high pressure fuel above the plunger head has an escape path through the helix and back out the port, thereby ending injection.

Now, go grab a beer, cause it's about to get deep.

There are upper helices, lower helices, and upper and lower helices.

Upper helices will vary the start of injection because The helix is what closes the port, not the actual plunger head. The amount of fuel delivered is also varied because the further the plunger moves before Port Closure, the less plunger travel there is to actually inject the fuel.

With a lower helix, the port closure or beginning of injection is fixed because the plunger head is what closes the port, but the end of injection is varied. These are the types of plungers that are used in the P pump As well as the overwhelming majority of A pumps for Cummins applications.

And finally, the upper and lower helix. The upper helix controls the start of injection, and the lower helix controls the end of injection.

So what does it all mean? All other things being equal, the VE pump should start a little easier, and get a little better fuel economy. So for max economy, the VE should be a little better pump. The inline pumps, especially the P pump, are better for max power.

The VE pump has the handicap of having only one pumping plunger. You can only get so much fuel into the plunger to be delivered in a 1/4 turn at 1500 rpm.

The inlines however, get a full turn of the camshaft to refill and prepare to repump. So they can deliver a larger quantity of fuel.

Sorry for the 200 page novel. Hope this helps with some of the questions floating around.

Later,
SS
 
#36 ·
What are the differences in the A pump & P pump. Pics? I have 2 4B motors
One is a 4BTA Has the later style water to Air cooler the inline pump has slotted mounting holes to adjust timing?? Next is a 4BT that was air to air also has the same slotted holes. On the dodge 6bt you have to bust the gear off to adjust timing. What the procedure to adjust timing on one with the slotted holes?
 
#37 ·
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