Don’t over look your friendly local Jeep dealer. Ask for the Mopar Performance Catalog. They have a host of performance items for the 4.0, most of which should fit the 232/258’s. They have a stand-alone fuel injection system designed specifically for the carbureted engines. It includes, manifold, injectors, fuel rail, wiring and brain box. Don’t know about the price, but it should provide the most – STREETABLE – horsepower you can get.
Don’t forget about the junkyards, Jeep has been building Cherokees with 4.0’s for 15 years now. The 4.0 comes with a nice steel tube (single) header. Since the 4.0 was designed to spin faster than its older brothers, the exhaust system is bigger in diameter, so you may be able to pick-up a cheap upgrade there. (BTW, I live in Arizona and we do not have a rust problem, you may not be able to use junkyard exhaust systems where you live).
My stone stock 4.0 makes really nice power from 2000-4500, so the cam for one of these may work nicely in your 232/258.
Performance Automotive Warehouse (PAW) stocks some aftermarket rebuild parts for these engines although I have never looked at anything but their ad’s in car mags.
Good Luck,
Steve
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'98 Jeep Cherokee, 4.0
'56 Willys P/U, 226L
