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Unread 04-12-2007, 04:23 PM   #1
saw2239
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Engine rebuild, lookin for power

Well it finally happened, the 4.0 in my 1996 zj has hit the hay and it is time to rebuild.

I've pretty much just lurked the forums so I have read a bunch of threads about stroking the 4.0 and while I would love the added power, I am a poor college student without much in the ways of funds and this would be my daily driver. I'm also not sure if a stroker would pass CA emissions.

But while the engine is out of the Jeepers I was wondering if there are any internals that would give me some nice performance boosts?

I looked and saw that mopar offers Purple camshafts but it doesn't list what kind of performance I could get out of them, and I'm wondering how their longevity is?

Are there any other upgrades I should take a look at while my engines out?

edit: forgot to mention that this is the 2WD variant and while I do take it out on trails occationally, it's mostly going to be seeing southern californias freeways.

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Unread 04-12-2007, 11:22 PM   #2
4.7stroker
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Stroke it, 4.2 crank and rods with 4.0 pistons.
Get the crank and rods from a local pick a part take the whole shebang to the machine shop.
The only additional cost is the cost of the 4.2l crank n rods.
Mine cost me around $1500
Don't know about Cali emissions though so just ignore me if the machine shop says it won't work.......

Dwayne
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Unread 04-13-2007, 11:35 AM   #3
saw2239
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That sounds like a good idea to me. I'm guessin it would be 91 octane?What kind of gains should I expect from using the 4.2 crank and rods and does stroking pretty much require an overbore?

Also what do you guys think of those purple cams? Are they worth it? What kinda power and longevity should I expect to get out of em?
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Unread 04-13-2007, 03:49 PM   #4
curtjames37
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You don't have to overbore. The 4.2L crank and rods will give you 4.5L of displacement just itself. You can overbore to 4.6L or 4.7L or higher if you are feeling brave. Don't have any experience with the Mopar cam.

I say go for it. I would at least do a 4.6L though. Afterwards get that thing on a dyno and post the results for us all to marvel at!

Lots of info on stroking the 4.0L:
http://jeep4.0performance.4mg.com/stroker.html
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Unread 04-13-2007, 05:16 PM   #5
4.7stroker
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No idea on the purple cams, I just went with the tried and true Comp Cams.
The stroked combo "should run on 87-89 comp of 9.75-1 or so.
Reduced squish height will boost the garbage out of the tail pipe that may be a deal breaker.
Are there any Cali residents out there that can chime in on that.....
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Unread 04-13-2007, 06:19 PM   #6
saw2239
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Thanks for the link Curt thats exactly the kind of info I was looking for.

Got back from the mechanics and they quoted me around $3500 just for your basic rebuild with some performance stuff. I've also got a few guys who are figuring out prices for me but I'm not too optimistic about them.

I'm semi mechanically inclined so that nasty price got me wondering if it was something I could do myself and not have to worry too much about messing it up. Kind of one of those I took a shop class back in highschool deals, but it would be great if its something that I could buy a rebuild kit along with some stroker parts and build it up in my garage.

Would that be feasible or do you guys think its pretty much a must take to a mechanic deal?
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Unread 04-13-2007, 07:22 PM   #7
4.7stroker
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3500 bux wow you could buy a complete engine from golen or hesco and come in at the same price.
I guess it pays to be in good with your local machine shop.
$13 a hole for rebore
$80 to regrind the crank
$6 ea to press on the pistons
$7 ea to refurb the rods
$80 to clean everything
$80 to deck the block
$540 for pistons/rings/bearings/gaskets/Comp Cam
I already have a new/rebuilt head $400

Works out a lot cheaper doing everything your self and working with a machine shop.

Dwayne

Last edited by 4.7stroker; 04-15-2007 at 06:23 AM..
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Unread 04-16-2007, 09:15 PM   #8
saw2239
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Well I got the rents approval to clear out the garage so it looks like I'm definitely going to be able to do the rebuild myself .

Now the only question is if a stroker will pass Ca emissions standards? Anyone with a Jeep in CA that can confirm if it'll pass?
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Unread 04-16-2007, 09:48 PM   #9
curtjames37
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Pretty sure it will. A newly rebuilt stroker will probably pass easier than a tired 4.0.

I can't guarantee this 100% since I have neither a stroker nor emissions testing.
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Unread 04-19-2007, 06:42 AM   #10
CapSr
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I am building one now (not a stroker) 4.0 bored .040 over had the crank turned Everything new in the engine except Rods, Xtreme 4x4 CompCam, K&N Air Filter, Melling High Volume Oil Pump, Pacesetter Header, Dynaflow Cat Back,I Ported and Polished the Head, Ported the Throttle Body,Accel Cap and Rotor, Taylor Fire Power Wires, and E3 Plugs And came in under $1700.00 Still in the Process of putting it togeather now... Trans is next Comp. rebuild kit for it was $302.00 w/tax
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Unread 04-19-2007, 06:47 AM   #11
heywaitfourme
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search my name on this forum. You will find all the info you need for a rebuild/stroker.

The stroker can be done for around 400 dollars, WITH NO BORE. If you bore it, you will just have to add in the machine shop charges.

Promar performance is your best bet for picking up the rebuild kit. Modularfords.com forums is your best bet for picking up some 24# injectors. Bought 4 sets from them, most expensive I paid was 80 shipped with only 2400 miles on them and flow tested. Local jeep store for the .043 mopar performance head gasket (28 bucks). Radio shack to build your adjustable MAP sensor ( 10 bucks). Initial tune on the map, good place to start.....5.15 on a 4.6L and go from there till all knock is gone and plugs look good. Also, change your plugs to atleast, ATLEAST one stage colder.

I run a 4.7L, two stage colder plugs, map at 5.12V, 89 octane(personal pref. could run 87 but choose not to) and my jeep flat out hauls. I have stock gears with 31's and I have no problems goin 75 down the highway in 5th, or pulling a ranger with 10" lift thru mud holes cuz his tranny blew. Very worth while mod, and if I get more time, I will finish my write up of my stroker motor.
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Unread 05-16-2007, 05:04 PM   #12
saw2239
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Well I finally got access to my garage so all of the components in my engine bay have been removed and I'm getting ready to pull the engine tomorrow.

Ive decided to go the route of a 4.6L stroker, but in every other buildup I've seen they've used '91-95 Heads, any reason why I cant use my '96 head unit?

Edit: trying to pull the engine with the tranny but I can't seem to figure out how to remove the front bumper assembly to allow me to do this. It seems to be attached completely with one time use parts and I am hesitant to remove them. Does anyone have any suggestions on how to go about removing it?

Last edited by saw2239; 05-21-2007 at 03:57 PM..
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