I am looking for engine upgrade tips for a 4.2 rebuild.

pushead · #1 (**permalink**) 03-15-2005, 03:53 PM

Let me just start by saying I am not swapping any other motor and have no desire for fuel injection. With that out of the way does anyone have any rec's on pistons, cam shafts, where to get a dececnt 4.0 head to bolt on, ect. I am going to buy the yella roller rockers for the 4.0 head and a pacesetter header. This will be a total rebuild in my garage.

Junkpile · #2 (**permalink**) 03-15-2005, 06:34 PM

What Jeep is this in, and what is the main type of wheeling it will be doing?

What transmission are you running, and what is the differential ratio?

BigDaddys88YJ · #3 (**permalink**) 03-16-2005, 12:00 AM

Best bang for the buck go with the 4.0L head and save the rest of your money for gears,lockers,tires,take the wife out to dinner,take the girlfriend out to dinner,go to the strip club and etc. How much HP do you really need for a jeep?

pushead · #4 (**permalink**) 03-16-2005, 09:28 AM

Its a 88 yj. Currently has 3.07 gears and 31s with a sorry peugot tranny. This stuff is of no importance thow. It is all being replaced in moderation. The rear end is starting to scream now, so I have a 8.8 with 4.10's on standby and when the tranny goes I will upgrade it accordingly. I am only concerned with the motor rebuild this round. I use my jeep mostly for evening drives and weekend use. With weekly wheeling in the dunes and occasional rock quary. Not to much to tear up in FL. I would call it moderate wheeling. Nothing to hardcore. Also I am not after major HP. I just want a nice rebuild with quality parts and a little extra torqe.

Junkpile · #5 (**permalink**) 03-17-2005, 07:47 PM

I would do a cam swap to go along with the head swap. Why go through the trouble of putting on that free flowing head, and then cripple it with a crappy camshaft?
I don't know that I would really do much else besides a header, a bigger(and better) two barrel, and a hotter ignition. You won't kill the bottom end on a 258, the torque is going to be there no matter what you do. When picking parts, emphasize building mid-upper rpm HP up to about 5,000rpms.

pushead · #6 (**permalink**) 03-18-2005, 11:14 AM

I was looking into getting a Reed Camshaft. Still making that decision. Already have a mack daddy weber carb. Now I am torn on which header to get. I was checking out the clifford performance web site and found a nice rebuild kit with a cam and i noticed they have a dueal header set up they claim adds some nice tourqe. http://www.cliffordperformance.com/Site04/Home.htm

Junkpile · #7 (**permalink**) 03-18-2005, 08:09 PM

I'm a Comp Cams fan myself.

The Comp grind# X4254H would be exactly what you want. It's a hydraulic flat tappet in their Xtreme 4x4 line. It's a split duration with 210 degrees intake/218 degrees exhaust @.050 lift. It will have a nice idle and pull HARD up to about 5000rpm.

Snitty · #8 (**permalink**) 03-19-2005, 05:00 AM

is that the same cam they recommend for the 4.0

Junkpile · #9 (**permalink**) 03-19-2005, 01:10 PM

Quote:

Originally Posted by Snitty

is that the same cam they recommend for the 4.0

No. The ONE cam that they have that they recommend for the FI 4.0l is a little more tame than that.

Grind# X4250H-13 Duration @ .050" is 206 intake/212 exhaust
.460" intake/ .476" exhaust lift 113* lobe seperation
Intended operating range is idle-4800 rpms

I'd like a little more camshaft in a 4.0 that I was really going to be pushing.