What can be done to improve my setup. I dont know exactly what the specs are. Had an engine building friend do all the work at his shop but hes passed away now. to my knowledge this is what i have so far. the old cam gear on the comp cams went south and was replaced with the lunati 63500 along with new bearings pump lifters etc.... cold weather is here and it pings more than in the summer. Thinking of pulling it and getting this right. always using 93. the motor just doesnt feel there. not sure if the quench height is correct or what was taken off the block or head. its definitely .30 over but people said they didn't recognize the pistons. still idles like it has a cam in it and really doesnt like anything over 3500
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Pistons ?????
9.6:1 CR
comp cams 68-232-4 at first. now runnning lunati 63500
Mill block deck 0.020"
regular head gasket
0.050" quench height
Ford 24lb/hr injectors
Plugs - ngk bkr6e
264hp @ 4900rpm, 324lbft @ 3500rpm
You shouldn't be pinging with 9.6:1 CR. I would take a look at the distributor/cam sensor indexing. Pinging, rough idle, etc point to a mis indexed distributor. I've had the 68-232-4 cam and the idle was fine. You should have also replaced the distributor gear when the cam gear died. You also don't state what year and model you don't have. Where did you get your injectors? Were they pulled from a salvage yard or used? If so they could be partially clogged. Do you have a wideband sensor?
You also don't have the 4.0l 6.125" rods. Those pistons are 4.0L replacement pistons, which can not be used with the 4.0L rods. You most definitely have 4.2L rods.
idle was fine with that cam also for me. The lunaiti cam idle isnt rough but its not butter. Distributor was replaced with cam. 91 yj, and injectors were used ones. maybe i should have them sent out and cleaned? anything i can do to confirm all the engine specs are within reason to eliminate some guessing? like compression and quench ....
