4.2L from 85 cj

Swaping 258 to 4.0, 4.0 parts to 258 etc!
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mtmech
Posts: 4
Joined: November 14th, 2010, 9:57 pm
Vehicle Year: 1997
Vehicle Make: jeep
Vehicle Model: wrangler

4.2L from 85 cj

Post by mtmech »

have a 97 tj wanting to do the 4.6 stroker. now my dumb questions. stumbled across a 4.2 for sale. kinda cheap. was wondering if my intake would bolt to it. also my ax15 trans that i have also bolt to it? injectors? etc. also the engine mounts the same as my 4.0L thats in it right now. just askin before i make an offer or make a purchase. thanks. and critisim is welcome. but at the same time... im still learning ALOT by reading.
92tank
I made it to triple digits!
I made it to triple digits!
Posts: 188
Joined: August 21st, 2010, 6:32 pm
Stroker Displacement: 4.5
Vehicle Year: 1992
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: 4.2L from 85 cj

Post by 92tank »

you use the 4.0 block you have now and put the 4.2l crank and rods in that. you dont use the 4.2l block
mtmech
Posts: 4
Joined: November 14th, 2010, 9:57 pm
Vehicle Year: 1997
Vehicle Make: jeep
Vehicle Model: wrangler

Re: 4.2L from 85 cj

Post by mtmech »

figured as much. problem is block i have atm has a hole into the #6 water jet. piston fell apart and the rest was history. not sure why but i figured why i had low oil pressure real quick. after i changed the oil.. filter.. pressure switch.. my next step was to drop the pan. and well after that happened i did and found my piston.
stroked'73
Making Progress
Making Progress
Posts: 79
Joined: March 30th, 2008, 1:35 pm
Stroker Displacement: 4.6L
Vehicle Year: 1973
Vehicle Make: Jeep
Vehicle Model: Wagoneer
Location: Montpelier, Vermont

Re: 4.2L from 85 cj

Post by stroked'73 »

Tranny will bolt up - might need a different pilot bushing, that's all. Bolt patterns are the same for 258's and 4.0's, as well as AMC 304 and 360 v8's.
But you'd be going backwards with a 4.2, better to find a 4.0 engine or block for sale for cheap. It wouldn't be worth it to put your intake on the 4.2 either - would be a pain to get it to align and even then the head doesn't have the recesses in the ports for the injectors.
No dumb questions here - we're all learning to some degree or another!!
1973 Jeep Wagoneer - 4.6L basic stroker, Q-jet/Offy dualport, Comp 68-231, .043" HG, 9.79 scr/8.56 dcr, crappy quench
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