4.0L HO Jeep Engine Build

fishy68 said
That's a right stout cam for a stocker. Right in line with some of the old performance cams of the late 60's to 1970. No wonder those engines ran so good right off the floor. Also I bet with your compression and good quench you will be able to run on 89 octane. Possibly even 87 octane. I noticed when shopping for valve springs, retainers, and locks for my Iron Rams they listed a lot of the same parts for the Jeep 4.0 as the magnum stuff.

Yep Fishy, that cam is suprisingly large for a stocker. In retrospect I suppose the 4.0L HO is really kinda of an inline 6 Magnum.

This thing sure didn't have any quench before, although it was fully cabable of it with those pistons and heads.

MOPEkidD-3 said
So that's why my 'new' 1993 Cherokee 4.0HO feels quicker than my friends' '97 and '00 Wranglers. And they're all stick-shift too! It's pretty surprising for 177k miles too. Can't wait to do a full exhaust, bored TB, and cold-air intake on this thing.

I'm surprised at the lack of aftermarket downpipes for these engines, the stock ones SUCK. Too small to begin with, and lots of bad compression bends...ugh. I might try to build a system with a removable section of pipe in place of the cat altogether, actually. I just hate the way they sound and El Paso County doesn't emissions-test -- yet.

You got the good one in the good years ('91-'94) with the bigger port heads and bigger cam. :) Even doing nothing at to all these engines it's suprising how quick they are. We also have OBD1 computers which are the most forgiving in regards to modifications.

You are absolutely correct about that goofy downpipe. That's another issue I was going to bring up in a later installment. Borla offers a header with a downpipe but they are about 600 bucks. If I had that kind of money I'd get the Clifford and have a custom exhaust done. I'm going to either bring mine in to a muffler shop and have a real one made or make one myself. More to come on this. :read2: