Jeep Strokers

Ive been on NAXJA.org for a while, but just signed up here. Im trying to put together a build plan for my Jeep. Here's the background: It's an 87 Jeep Cherokee Laredo. The engine is an 88 4.0 Renix. The motor its self has about 170K on it, with the exception of the lower end which has under 10K on it. (crank shaft, bearings, etc.) I want to build a stroker out of the existing engine. I also replaced the oil pump, harmonic balancer, timing chain and some other things when the lower end was rebuilt. The rings are original and so is the head. I have a blown head gasket currently. My goal is to have a budget 4.5 Liter Stroker. I know some info about the stroker, but im hoping that the experts here can really help me hone my knowledge and get a good plan of attack. I would like to try and take care of everything this time around and have a motor that can last me. See my list below ( and hopefully improve or change it). I would like to have the engine run on 87 Octane if possible. The Jeep is normally, my daily driver. Can I use the YJ Wrangler 4.2L crankshaft without having to modify the harmonic balancer? I believe I read that somewhere. Anyways, that's the basic outline, any helpful advice on my stroker build would be much appreciated. Thanks.


Parts
-1987 YJ Wranger 4.2L Crank and Connecting rods
-? Lb pr. hr fuel injectors
-New 4.0L gasket set
-

bump

Welcome aboard. . The balancers don't need to be modified. I don't remember for sure but iirc that crank should have the short snout. If not you just need a spacer. As for the rest of the parts, what exactly are you wanting? My dd probibally differs from yours and yours from the next guys and so on. There are lots and lots of builds on here covering just about all the bases.
Oh, just remembered. You should have the balancer balanced. Its been an issue ,but that's not really a mod. Just a blueprint

x2 on balancing the balancer. They are frequently out. I haven't have my OEM one balanced, but the Performance Products I am using now needed quite a bit of balancing. That and I had to make my own timing marks on it. Wouldn't recommend that one.

You said you have 10k on the short block. What are you planning on replacing in the block?

Well, I would like to build a 4.5 stroker, I do not want to build a 4.6 liter or bigger. Hopefully, I can have this be an economically efficient build. I would like to just change the crank and rods on the block. Do you think I could just go with new rings? or should I have it re-sleaved? Little things like that are what I would like to narrow down a bit. I have a free flow exhaust system, stock TB. Fuel injectors are another thing I should address, but one of my main concerns is for the motor to run on 87 octane and not ping. Can it be done? I, by no means, expect this to turn into a hot rod motor, just a good motor for my daily driver with a little extra punch. One more thing I forgot in my op, The head on the motor is original and has 170K+ on it. Do you think a viable option would be to rebuild it, or buy a newer head so I don't have to shell out the extra cash to rebuild. I would plan on keeping all of my Renix parts (manifold, tb, etc.) if I did get a newer head.


PS: Thanks for the Welcome! .........and when you say, balance the harmonic balancer, do I just take it in?? or balanced on the crank?...

You had the cylinders bored and honed but you didn't install new rings?

It doesn't use sleeves.

i would just rebuild your head. if you get a newer one, you still might have valves full of crap and stuff. even if you stay with the stock valves, etc, a good cleanup and valve job never hurts

X2 on redoing your head. It would suck to get another AND have to redo it.

Just re-read op . so you replaced the crank,bearings,oil pump, timing chain, and misc........ So no bore or hone? If so you really should hone and ring it ,at least.

At the time of rebuilding the lower end, I did not have the money to replace the head gasket or the rings. (I know, very stupid move) So, the rings are original. So, I should hone it, and put in new rings. I will take your guys' advice and rebuild the original head as well. The formula below is what I'd like to follow.

Couple questions about it. The bold stuff. I would like to get an aftermarket cam, for a nice sound vs. the HO Cam. Can I buy standard bore pistons from Autozone/ORiellys etc.? Should I use 19 lb hr injectors vs the 24s? The 24s seem a little heavy from what Ive read. And, im still wondering about using 87 octane?


4.5L "Poor man's" simple stroker

~ Jeep 4.2L 3.895" stroke crank
~ Jeep 4.2L 5.875" rods
~ Speed Pro 677P standard bore pistons
~ 9.05:1 CR
~ Stock 4.0 HO camshaft
~ Stock HO cylinder head
~ Stock 0.051" head gasket
~ 0.097" quench height
~ 2.25" exhaust
~ Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
226hp @ 4600rpm, 304lbft @ 2000rpm

jk333 wrote:Ive been on NAXJA.org for a while, but just signed up here. Im trying to put together a build plan for my Jeep. Here's the background: It's an 87 Jeep Cherokee Laredo. The engine is an 88 4.0 Renix. The motor its self has about 170K on it, with the exception of the lower end which has under 10K on it. (crank shaft, bearings, etc.) I want to build a stroker out of the existing engine. I also replaced the oil pump, harmonic balancer, timing chain and some other things when the lower end was rebuilt. The rings are original and so is the head. I have a blown head gasket currently. My goal is to have a budget 4.5 Liter Stroker. I know some info about the stroker, but im hoping that the experts here can really help me hone my knowledge and get a good plan of attack. I would like to try and take care of everything this time around and have a motor that can last me. See my list below ( and hopefully improve or change it). I would like to have the engine run on 87 Octane if possible. The Jeep is normally, my daily driver. Can I use the YJ Wrangler 4.2L crankshaft without having to modify the harmonic balancer? I believe I read that somewhere. Anyways, that's the basic outline, any helpful advice on my stroker build would be much appreciated. Thanks.

Parts
-1987 YJ Wranger 4.2L Crank and Connecting rods
-? Lb pr. hr fuel injectors
-New 4.0L gasket set
-

With low mileage 4.0 engines being scarce these days, I'd recommend reboring the cylinders and going for a 4.6 stroker. If your aim is to keep costs to a minimum, you'll be looking to build something similar to my "poor mans" stroker combo:

4.6L "poor man's" stroker

'87 YJ 4.2L 3.895" stroke crank
'87 YJ 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
'88 Renix 4.0 camshaft
Ported '88 Renix cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines
MAP adjuster

As long as your cooling system is up to scratch and you use a 180* t'stat, you should have no problem running 87 octane.

Cheromaniac wrote:

jk333 wrote:Ive been on NAXJA.org for a while, but just signed up here. Im trying to put together a build plan for my Jeep. Here's the background: It's an 87 Jeep Cherokee Laredo. The engine is an 88 4.0 Renix. The motor its self has about 170K on it, with the exception of the lower end which has under 10K on it. (crank shaft, bearings, etc.) I want to build a stroker out of the existing engine. I also replaced the oil pump, harmonic balancer, timing chain and some other things when the lower end was rebuilt. The rings are original and so is the head. I have a blown head gasket currently. My goal is to have a budget 4.5 Liter Stroker. I know some info about the stroker, but im hoping that the experts here can really help me hone my knowledge and get a good plan of attack. I would like to try and take care of everything this time around and have a motor that can last me. See my list below ( and hopefully improve or change it). I would like to have the engine run on 87 Octane if possible. The Jeep is normally, my daily driver. Can I use the YJ Wrangler 4.2L crankshaft without having to modify the harmonic balancer? I believe I read that somewhere. Anyways, that's the basic outline, any helpful advice on my stroker build would be much appreciated. Thanks.

Parts
-1987 YJ Wranger 4.2L Crank and Connecting rods
-? Lb pr. hr fuel injectors
-New 4.0L gasket set
-

With low mileage 4.0 engines being scarce these days, I'd recommend reboring the cylinders and going for a 4.6 stroker. If your aim is to keep costs to a minimum, you'll be looking to build something similar to my "poor mans" stroker combo:

4.6L "poor man's" stroker

'87 YJ 4.2L 3.895" stroke crank
'87 YJ 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
'88 Renix 4.0 camshaft
Ported '88 Renix cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines
MAP adjuster

As long as your cooling system is up to scratch and you use a 180* t'stat, you should have no problem running 87 octane.

Thanks Cheromaniac. That gives me a pretty good idea of where to start. Im sure I'll have some questions along the way.