p pump 12v/ 24v swap

dsl kicks gas

dsl kicks gas

Runnin on Broke
Joined
Aug 13, 2007
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ok im in the process of dropin a 12v in my 98.5 truck, the 24v valve was having injector pump problems and wound up breaking the cam (long story)

i have a 96 p pumped 12v out of a school bus, i need to get gauges working.

i dont think the water temp, and oil psi will be a problem, but the tach is what im worried about. any info on the tach and shut off soliniod will be helpfull!!
 
dsl kicks gas said:
ok im in the process of dropin a 12v in my 98.5 truck, the 24v valve was having injector pump problems and wound up breaking the cam (long story)

i have a 96 p pumped 12v out of a school bus, i need to get gauges working.

i dont think the water temp, and oil psi will be a problem, but the tach is what im worried about. any info on the tach and shut off soliniod will be helpfull!!
Click to expand...

Ive heard of people just running a pull cable into the cab and when they go to shut it they just pull the cable.
 
dsl kicks gas said:
ok im in the process of dropin a 12v in my 98.5 truck, the 24v valve was having injector pump problems and wound up breaking the cam (long story)

i have a 96 p pumped 12v out of a school bus, i need to get gauges working.

i dont think the water temp, and oil psi will be a problem, but the tach is what im worried about. any info on the tach and shut off soliniod will be helpfull!!
Click to expand...

You will need to use the cam gear off your 98.5 and get a cam sensor adapter plate to bolt up where the 12v timing pin usually goes and grind a little bit out of the cover so your 24v cam sensor can read the little notch in the back of the 24v cam gear. For the solenoid you have to wire it up to a relay with 12v, key on power, and ground.
 
Does the 12v have a provision to mount a crank sensor? On the 98.5, the ECM uses the crank sensor for the tach.
 
you will more than likely need a 98 12v wiring harness, and good luck my friend!! they are mighty hard to find, they are right around 3500 at the dealer. i know a guy that did that same conversion and he is in the hunt for a harness to get everything working. they have tried jerry rigging everything and it came down to him needing that harness to making that newer dash work with that older motor.
 
I Just went through the cam sensor adaptor deal last night. Not thinking, I put my 12 v gear housing on and cam ,(24v cam),back in befor getting the adaptor and when it showed up I found out you need to take a die grinder or dremel to it.The adaptor has a raised part on the back that goes into the 12 v timing pin hole, bolt the adaptor up and take a sharpie in side the sensor hole and then go in there and oval it out. It would make much more sense to have the housing off. I ended up pulling my cam 1/4 the way back out so I could catch all the aluminum shavings. (thankfully my over head was still off.) I'm guessing when you buy the kit their housing comes machined all ready. Maybe I saved you some trouble :blahblah1: I'm still looking into the shut down solenoid, I was told the 12 v trucks and a 70amp relay triggerd by the starter. But I also have a schematic that came with my solenoid I want to look into yet. Good luck. -Ethan
 
Tate said:
Does the 12v have a provision to mount a crank sensor? On the 98.5, the ECM uses the crank sensor for the tach.
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Some do(STORM blocks) however they are rare. The way I have been doing them......is to machine the holes for the sensor and use a 24v crank.
 
Just ppump the 24 valve motor. How many miles did the 24v motor have. If everthing else was okay, just do the conversion and order a 450$ drop in 24v street cam. This way you wont have to worry about the hole wireing harness.
 
ILLINOISRAM said:
Just ppump the 24 valve motor. How many miles did the 24v motor have. If everthing else was okay, just do the conversion and order a 450$ drop in 24v street cam. This way you wont have to worry about the hole wireing harness.
Click to expand...


i got a good deal on the 12v with less than 60k miles on it and my 24 had 260k.......looking back i should of built my 12v with my 24v block......

i got the 98 12v harness, but decited not to use it.

it has all the sensors on it and everything(for auto truck, will work fine on manual as well) i want to get 250 out of it
 
Heres some pics of the cam sensor adaptor , you can see the mark where the sensor actually ends up. -Ethan
DSCN2166.jpg
DSCN2168.jpg
DSCN2169.jpg
 
the only problem is i have already sold my 24v cam gear and i belive that the 98 reads the tach signal off the crank sensor......i could be wrong. i think im just going to get a 2" isspro 5k tach and call it good for now lol
 
i realy dont want to spend the money right now, i can deal with the tach not working as long as everything else does
 
tach wont work.....big deal.....ill mount a 5k isspro tach on a 2" steerign collum mount. the stock tach only reads to 4k......i have shimed 4k springs so i want the biger tach anyways lol
 
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