So, I want a Hemi in my 98 ram 1500. I intend to use a megasquirt for fuel and ignition. My question is this: can I leave the stock pcm in place for things like running the dash/tach/etc..? My thought was to adapt as many sensors as necessary, but leave the fuel and spark from the stock pcm disconnected. I was hoping, that I could adapt the original style crank sensor to allow tach operation.

Thoughts?

Trans will remain NV3500 5speed.

 

Good luck with that. Do a search here on DF. There is a long running thread on this topic. Been years and it still isnt running. Not worth it IMO. But find that thread, it has has a lot of info in it.

 

Does that transmission even match a hemi?

 

I searched hemi swap, but haven't found what I'm looking for. I keep finding swaps involving integrating the stock pcm into the earlier wiring harness. I can see that as a significant obstacle. I intend to use a "stand alone" system for this reason. I just need to know how much feedback the 98 pcm in my truck needs, and how it receives a tach signal. Met a guy once with a high 9 second dakota. His dash still worked using the stock pcm, although none of it was connected to the motor.

 

To my knowledge, the hemi has the same bell housing pattern as any LA small block. I have seen mention that the top bolt hole is absent, but the rest line up. I'm sure there will be some measuring going on.

 

This guy put a Hemi in his Dakota, should be fairly similar to putting one in a Ram, https://dodgeforum.com/forum/2nd-gen...with-pics.html

 

Thank you for the link. It was very informative, but not what I'm looking for. I can handle the welding, and fabbing. I can handle the wiring too, as far as making the motor run. I really need to know how the stock pcm from my '98 ram works, more than I need hemi info. Maybe I should have titled the thread differently. Again, I intend to operate the fuel and ignition with an aftermarket computer. What I want to keep stock is just the dash, namely the tach. I think I can rig up the stock crank sensor set up, and I want to know if the tach will function based on this output. I know it will have a permanent check engine light- don't care. I know I will lose cruise control- no biggie. I will have complete control over the fuel and ignition curves, and I won't need a little magic box with a downloaded tune to get it, just a laptop.

Thank you for the replies, everyone. Can anyone answer the above question ? Should I make a new post somewhere else, and maybe ask the question better ?

 

You might need to find someone who does custom PCM's and see what they have to say...

 

Most of the dash gauges are driven via the PCM, thru the central timer module. I think it would be easier to just install different gauges....

Have a read of this thread.

 

That's the thread I was referring to, thanks HeyYou.