12valve2nv

I did a 12valve swap in a 98.5 24valve truck recently. The swap itself is not bad at all, just like swapping a 24v for a 24v. The problem we raninto is wiring....the 12valve wiring is quite a bit different. The biggest thing is we used the 12valve PCM and the fuel gauge, speedo, temp gauge and many sensors i.e. check engine light.....none of them work. I have tried to splice, dice and hack the harness best as possible but it just won't happen. We have decided to do a complete harness swap cab forward...using a 12valver truck as a donor. To get the truck running was super easy....the 12valve needs 2 fuel lines, starter input and power to the fuel cut off solenoid to run thats it!

cummnz4x4pwr

this is the reason you reuse all of your 24v sensors harness and leave the cummins computer just attach it to the firewall but all you have to do is swap out all the sensors and your going to need an adapter to make the tach work and reuse your 24v cam gear.

jake

Mike Holmen

So my tranny will work right? I don't care about the check engine light. Its just a limp motor until my 24v is done up. Whats the worst thing that can happen?

joefarmer

So this is just to get you by until you rebuild the 24v with VP44? Hmm... Why not take the 12v block (assuming it's a STORM block or the 24v if it's not a 53), a good crank, new rods, 24v or CR pistons, 24v head (your PDR head), and the P-pump. Then you'd have a mechanical pump truck with really good airflow. You'd only need to buy the parts for the 12v pump conversion, a crank, wiring harness for a 98 12v and 98 PCM. I bet you can find these parts for under $5k Can and have a monster truck too.

I bet the trans will have trouble and, at minimum, you're going to need a different PCM. This is due to the auto's overdrive being controlled by the truck's PCM. The crank position sensor is different between the 21v and 24v. If you're just rebuilding the 24v, then you'll want to make sure the new crank has the tone ring (not sure what its called) to drive the 24v crank sensor.

brnadon.

Mike Holmen

The motor comes with ECM and wiring harness. Its complete with only 10k on the motor. It 913 motor with 215hp pump that has a #10 plate, valving springs and all the stuff. I was told that I could get the stopid pump on this motor. I'm thinking using some of 12v parts for the new monster rig that I'm building. I got the wife into thinking that my motor toast. Playing is way cheaper than buying a new STOCK rig or buying a stock 24v cummins motor. Its just a motor right. I could always sell a left over parts to pay for monster build. I already guy wanting the injectors and twins. I also have a guy wanting my old VP pump. Brandon whats the best spooling set of twins that you seen? I'm thinking about a bearing turbo for a primary and a 3b/70mm wheel bottom.

joefarmer

I would actually take a KSB1-2 over a B2 for a cool 600hp setup.

brandon.

Mike Holmen

I never seen how the gearbox housing looks on the 12v. Can the cam position sensor of the 24v bolt into the 12v gearbox housing? The manual says that the sensors is just under the VP pump. If not I'm sure the housing can be modified to work. Where is the crank sensor located at? Is it the rear of the motor near the bellhousing? I'm such a newbie

kelownadiesel

No,I think its near the balancer on the front.They call it the speed sensor I think

cummnz4x4pwr

Yes Ive designed an adapter that makes it to where you can bolt the cam sensor on to the 12v gear housing. pm me for more details.