XJ 4.7 Build

[wakeboard76]

So I thought it was about time I posted my build on here, I've been researching and dreaming of building a stroker for quite some time, and finally have the opportunity. Back in October I took my Jeep down to Slade, Kentucky for some serious wheeling. After an 8 hour drive down, my 4.0 decided it had enough, and broke a rod, punching a hole in the side of the block at 1am on the side of the parkway. After a very expensive trip in a uhaul towing the jeep back to Michigan, I decided I finally had the reason I needed to build a stroker. I have some experience rebuilding engines, I've already done two 4.0's, and I had done a lot of research on strokers. First I'll list my vehicle setup, then the build recipe.

'95 2 Door XJ
4.5" Rustys Lift
32" BFG M/T's
Manual transmission, stock 3.07 axle gears (for now).

I was planning on doing a fairly budget minded build, but at the same time, I only really want to do this once, so I've spent a little extra on some things. Here's the parts list so far.

4.0 Renix short block - $50
Complete 258 - $75
Comp Cams 68-232-4 Cam Set (lifters, springs, timing set) - $300 Ebay
'00 Intake - $50
Centerforce DF Clutch - $50
Rusty's Intake (already installed)
Cat back exhaust (already installed)
DIY Port and Polish of existing 4.0 head
Victor Reinz head gasket
Speed Pro hypereutectic pistons dished to 20cc's
Dodge 318 Magnum Injectors

I took the block to the machine shop and had them test, clean and bore it, they had to go .060 over to remove all the scoring, so I'm now looking at 4.66 Liters. The ground the 258 crank .010 under, reconditioned the 258 rods, and hung the pistons. When I got home, I realized that the pistons were not the ones I had asked for, but rather sealed power 525P's. Bummer, I really didn't want cast, and the combustion height is also .010 lower, so I have to have more decked off the block. When assembled it measured about .046 below the deck, much lower than I was hoping. I'm still debating whether to stick with these pistons, or try the hypers. I'm aiming for somewhere in the .045 range for my quench height, as I feel this is the most important factor in reducing detonation. I'm planning on dishing the pistons to keep my CR down. On the calculator, here's the numbers I come up with:

4.66 liters
SCR 9.79:1
DCR 8.46:1
Quench .0455

This is with a deck clearance of .0025 and a piston dish volume of 21cc's (using the cast piston).

I have a few concerns:

1. Decking approximately .045 from the block makes me think I'll need new pushrods so my lifters don't have too much preload.
2. Not 100% sure that my Comp springs will work on the 4.0 head yet, haven't really checked, but have read that there aren't many springs out there that will fit without modification.

Any opinions/Input is welcome.

[SilverXJ]

1. Decking approximately .045 from the block makes me think I'll need new pushrods so my lifters don't have too much preload.

You probably will need new push rods, but the best way to find out is measure once it is assembled. Dont' try to estimate by what you have removed, head gasket thickness, etc.

2. Not 100% sure that my Comp springs will work on the 4.0 head yet, haven't really checked, but have read that there aren't many springs out there that will fit without modification.

The retainers and locks won't as they are for a 4.2L head, which has larger valve stems. Also, if you still use the springs with a different retainer and lock you will have to install them at 1.80" (IIRC), when the stock install heigth for the 4.0L head is 1.64"

[wakeboard76]

Thanks for the info...where's a good place to find shorter rods?

The comp kit is listed for the 4.0, its the cam listed for fuel injection , so why the hell don't they make the parts fit properly?

[SilverXJ]

For the same reason they list the 68-231-4 not for fuel injection.

As for teh push rods, Smith Brothers and Trend are two good options

[wakeboard76]

Anybody know of the cheapest place out there to buy Mopar Performance valve springs?

[RAPTORFAN85]

Anybody know of the cheapest place out there to buy Mopar Performance valve springs?

http://www.jeepstrokers.com/forum/viewt ... ar+springs

[wakeboard76]

are they the mopar performance springs or not?

[dwg86]

P5249464 is the number for the mopar springs...Yes, they are the mopar springs.

[lafrad]

I tried to go buy the springs online but, no dice, it says they are out of stock.

[dwg86]

Call Jegs or summit. They have price matching. Be prepared to give them the web address and how to get to the page where it shows the price.

[dwg86]

you will also need p4452032 retainers. They are 4.99
http://shop.oreillyauto.com/ProductDeta ... r=P4452032

[SilverXJ]

you will also need p4452032 retainers. They are 4.99
http://shop.oreillyauto.com/ProductDeta ... r=P4452032

What about the locks? When I did my Mopar springs I went with the springs, retainers and locks. I don't know if the stock locks would work or not.

[RAPTORFAN85]

What about the locks? When I did my Mopar springs I went with the springs, retainers and locks. I don't know if the stock locks would work or not.

Stock locks will work with the mopar perf. retainers.

[dwg86]

Here is a set of locks on ebay. Good price.
http://cgi.ebay.com/ebaymotors/MoPar-Pe ... 240%3A1318

[wakeboard76]

Thanks for the help...unreal how expensive those things get.