Simple/Budget Stroker Build 2000 WJ 4.0 to 4.5

[rradford9]

I've been battling a slight tick/knock in the 4.0 for about 6 or 7k miles. The other day the knock was a lot worse when I cranked it up. It sounded 10x's worse and never went away after warming up/accelerating.

Pulling the oil pan today to see what we find, but I'm guessing one of the piston skirts has broken. So pending our results today I've started looking at rebuilding the 4.0L to a 4.5L or 4.6L "Simple Stroker" based on the info from Dino's site and ajeepthing.com.

My goals for the stroker are:
1) Rebuild it on a pretty tight budget. I'd like to stay under $1500, and around $1000 if possible (of course without sacrificing durability or quality).
2) Be able to run on regular or mid grade gas, but I'd prefer to stay away from premium.
3) The WJ is my DD and I use it to drive around town mostly. It does see HWY use about daily, but only for 10-30 miles. It also spends some time, about once an month, on the trails so I guess I'm looking for a pretty well rounded performer but I'd sacrifice some top end for a little better bottom end.

So this is what I'm thinking:
4.5L "Poor man's" simple stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP standard bore pistons
9.2:1 CR
Stock 4.0 camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
247hp @ 4900rpm, 300lbft @ 3500rpm

I'd like to get the quench height down a little bit, so I've read that you can increase the dish on the pistons to keep the same compression ratio. The sealed power pistons come with a 17.5cc dish, so if I decked the block .010" and upped the dish to 19.5cc's would the better quench height be worth it? Also, if I added a cam could I bleed off a little compression and increase HP/TQ?

[Mgardiner1]

i don't think i'd throw simple/budget in along with terms like "i want a tighter quench" or "throw in a cam"

If you are trying to keep it under $1500, and close to $1000, i'd reuse the stock cam, and take it easy on machine work (dish pistons, deck block) because the machine shop bill by itself will get very heavy, very quickly.

I wouldn't order standard pistons just yet either. Tear the motor down, and have a machinist spec out the bores. If they are at or beyond wear limit, you'll need to go to the next size up piston.

Good luck let us know what you find in the pan!

[rradford9]

Ouch!


#4 Piston took a shit

[Mgardiner1]

Yeah, that'll make her knock

Not too clear, but it looks like there is some scoring there. Definitly have it checked by a machinist before deciding on a size piston

[dwg86]

You might want to check out the Kieth Black pistons for your build. They aren't that much more money when you factor in the cost of buying a set of 258 rods, pistons, and dishing the pistons. If you do go with the 258 rods and 4.0 pistons, contact oletshot on this board. He milled my pistons. Great job, price and fast turn time.

I would dish the pistons or get KB pistons and reduce the quench. You will be able to run a higher compression and still reduce detonation.

[SilverXJ]

I wouldn't reuse anything from that engine except the block and rods if you go with the KB 944 pistons. I have seen too many late model cams damaged to advise you to reuse it. My original 2000 cam was damaged, the replacement 2002 (used) cam was damaged and I also have a very damaged cam from a 2000 block. Regardless if it was teh metal composition of teh cam or the lack of ZDDP in the oil I would not reuse it.

[rradford9]

Thanks for the advise so far...good stuff. Unfortunately I feel like my hope for a simple and low budget stroker may be out the window after seeing that piston. I have access to an older 4.0 block but aren't there some significant differences between the two?

[dwg86]

I think there are some differences on the bosses for the engine mounts.

[dwg86]

Also, if you buy a new cam, DO NOT buy the k-kit from comp cams...the one with the springs,retainers and keepers. The retainers and keepers in the kit are for a 258 valve(11/32 valve stem and 7 degree retainer) and will not fit the 4.0 valve. The 4.0 uses an 8mm valve stem with 8 degree retainers. So you are limited on valve springs, retainers and keepers, unless you change to a small block chevy valve.

If you want to keep your stock valves, you can use mopar performance valve springs P5249464, good for up to .525 lift and have the same 1.640 install height as stock springs. Use Mopar Performance retainers P4452032 with the MP valve springs. I think you can use your stock keepers, but for under $10.00 I would buy new Mopar Performance locks P4529218. You can buy a set for $6.95 + $2.00 shipping on ebay... http://cgi.ebay.com/ebaymotors/ws/eBayI ... &viewitem=

The best prices for the springs and retainers are on www.advanceautoparts.com. You have to buy them ONLINE, not at the store. Springs $6.99 each, and retainers $4.99 each, with free shipping on orders more than $75.00. Any problems return them to your local store.

You might be able to find some new behive springs that will fit the stock retainer. I haven't done any research on that yet.

[dwg86]

One more thing. If you build a new engine you might want to see about getting a new head. The older 0331 castings have been known to crack. Chrysler made some changes to the later heads. I'm not sure what year.

[rradford9]

I can get a complete running 4.0 from a local jeeper for $150. I'm trying to find out what its out of, but I think its an early '90's XJ...should I pick that up to use for parts?

[SilverXJ]

I have been told that they fixed the head on 03. However you can get an Alabama cylinder head that is supposedly fixed or you can get an earlier model head that requires a little bit of modification to use. I wouldn't use an earlier engine block as you may need to buy the accessories that go with that block or run into other issues fitting it. There is a list some place on this forum (check the FAQ) which lists which block casting number fit which jeeps as they came from the factory.

[rradford9]

Please excuse the noob-ness, but my eyes are crossing from researching over the last 48 hours.

There are a few 90-98 heads on Ebay, and one for ~ $260...is that worth getting? Is there a difference since my WJ uses coil packs?

IF my cylinders need rebored, which stroker recepie should I aim for in order to stay around my budget of $1500 and still run on reg. or mid grade gas?

Thanks for all the help

/noob (until next post )

[dwg86]

Does your idler pulley bolt to the front of your head? If it does, a older style head wont work unless you get all the brackets from the earlier engine. That = more money. So you might want to get a head from a later engine(2003-2006), or get from Alabama cylinder head. Or use yours and hope it doesn't crack.

To keep your budget low, you need to figure out what parts are going to cost. If you already have a 258 crank and rods, get 258 hypereutectic pistons for a 4.0 and send them to oleshot(send him a PM on this board) to have them dished. I have seen hypereutectic pistons and rings on Ebay for around $160.00+shipping. They are probably silvolite repackaged under a different name. That is what I got(clevite). Oletshot dished them to 21cc. Summit has the cheapest prices I have seen for the Speed Pro H802cp/H825CP pistons.

If you don't have 258 rods, you need to figure out how much the 258 rods+pistons+dishing cost is going to cost and compare that to the cost of Kieth Black 944 pistons(use the 4.0 rods from your engine). Its better to use a longer rod,

Keep the quench below .060(preferably.040-.050). You can run a higher compression with a tighter quench, and not get detonation.

So cam choice...1)You can call your local Chysler dealer and see how much a stock replacement cam would cost.2) Get a custom ground cam from Reed, Isky, or engle. 3) Get a cam from Comp, Crane, or Lunati. My personal opinion is stay away from crane. Comp has some grinds with lower lifts that would allow you to use your stock valve springs. Reed has a lot of different grinds to choose from.

I woundn't use your old cam unless you inspect it to make sure its not worn bad. From what I understand, the heat treated surface isn't very thick. To keep your budget low, choose a cam that will let you use your stock valve train. I'm not sure how much lift the stock springs will take. I have a cracked head off a 2000 WJ. I will put a dail indicator on it and see how much lift the springs will take.

[Plechtan]

I have heard about the cracking problem with the 331 head, but i really wonder what percentage of them failed? And if a head has been in use for 8 years and not failed, what are the odds that it will fail in the near future? So do you spend $500 on a new cylinder head assuming that your old head will fail?

If i had an unlimited budget, i would buy a new head, but for a budget build i would take the risk.

Another place to look for a had would be the local boneyard. you may have to take it off yousrelf, but it should run you $100 or less. I purchased a 2003 long block motor as a core from the local junkyard for $200. It did come with a 331 head, no manifolds or accessories.