[jon_xj90]

98 jeep sahara, 4.0L manual trans

putting a carbed small block chevy in it and wondering to all those who have done this, how did you adapt the stock tach to work.. if you were able to.

i understand it's computer controlled, is there a way to use the stock tach with an hei setup through adaptation?

 

[Yota Bill]

http://www.chiltonlibrary.com/content/images/WD/Chrysler/227/WD_Chrysler_227631.pdf

looking at the schematic for the instrument cluster, it looks as if they all share a common ground and positive source, and all get thier signals from the CCD bus from the PCM...it looks as if they may be regular guages though, so it may be possible to disassemble the instrument cluster, seperate the guages signal wires from the bus network, leave the shared pos and neg connections, and add in your own wiring to get the signals to the guages.

Keep in mind, this is really nothing more then theory based on the schematic for that model year, so the guages may actually operate differently then a standard guage...I would disassemble the instrument cluster, remove one of the guages, supply pos and ground, and then ground the signal connector and see if it pegs the guage at its highest point...if it does not, the guages operate differently then a standard guage, in which case you probably wont be able to run the stock guages

 

[jon_xj90]

thanks! i'll see if we can do that. it's still set up in 4.0L form, just trying to cover absolutely everything we can think of before even starting in.

if anyone else has more, please chime in. any input is appreciated!

we really wanted to leave the interior as stock as possible and arent fond of the dead tach on the dash idea...

 

[jonker87]

call dave at cascade 4wd he's know more about jeeps and doing v8 swaps than anyone I've ever met!
http://www.cascade4wd.com/projects/index.html

 

[mean_greenEXJAY]

http://www.greatlakes4x4.com/showthread.php?t=12025This is how to do it on a YJ, I do not know if it is the same for a TJ. But, something like this should work as long as the tach signal is a hardwired output from the pcm and not a message sent along the network.