New Stroker recipe

[martin809]

I am going to Stroke my 97 ZJ after Hunting season is over. How does this sound for a Stroker Motor
4.2 Crank
KB 944 Pistons 30 over
4.0 rods
Comp Cam 68-231-4
.043 Head gasket
24lb injectors
Larger Throttle body just not sure what size yet
Header
Better air flow

I have been researching this for awhile and have followed Dino's advice for most of this.
I would appreciate any input on this and will I have pinging or any problem running low to mid octane gas.

Thanks

[gradon]

Sounds like a good recipe to me. Nice paint job!

[SilverXJ]

Its going to ping on low octane gas. I had the same setup as you and it would ping using low octane. I could run midgrade but I would have to run it rich.

[martin809]

What should I change to keep it from pinging. I don't really want to run it rich, I am afraid it will kick on my check engine light and I won't pass my emissions test.

Thanks SilverXJ for your response

[SilverXJ]

I meant it was pinging under fairly heavy throttle, enough to put it in top open loop. It won't cause the check engine light to come on. Or you could just run premium

[Cheromaniac]

I am going to Stroke my 97 ZJ after Hunting season is over. How does this sound for a Stroker Motor
4.2 Crank
KB 944 Pistons 30 over
4.0 rods
Comp Cam 68-231-4
.043 Head gasket
24lb injectors
Larger Throttle body just not sure what size yet
Header
Better air flow

I have been researching this for awhile and have followed Dino's advice for most of this.
I would appreciate any input on this and will I have pinging or any problem running low to mid octane gas.

Thanks

Looks like you're thinking about a 4.6L version of this recipe from my site:

4.7L medium-buck stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith-Black Silvolite UEM-IC944 +0.060" bore pistons
9.6:1 CR
CompCams 68-231-4 206/214 degree camshaft
CNC ported HO 1.91"/1.50" cylinder head
Mill block deck 0.020"
Mopar/Victor 0.043" head gasket
0.051" quench height
Flometrics F&B 68mm billet TB
Accel 26lb/hr injectors with stock 49psi FPR for '96 and later engines.

You'll almost certainly need 91 octane gas for this version at sea level unless it's pretty cold outside. Then you might be able to run 89 octane. A 180* t'stat and a good cooling system (new stock 2-row radiator, high-flow water pump) help tremendously.
A 62mm TB mated to a '99+ intake would be great for your application, and 24lb injectors should be OK.

[martin809]

Thanks Dino, that is what I am shooting for. Do you think I need to mill the block or if it is straight can I leave it alone? I will stat collecting parts very soon.

[Cheromaniac]

You'll almost certainly need to mill the block but how much will depend on the deck clearance that you're aiming for. You'll need to do a mock up assembly of the bottom end to see how much deck clearance you have (measure with dial indicator) before you mill the block deck. That way you'll know exactly how much is needed.

[martin809]

Some things have changed since this post. I have collected alot of the parts except for the Pistons and Crank. I was thinking of just getting the crank and staying stock on the pistons. 4.5 stroker.
My question is do I have to use 4.2 rods or can I stay with my 4.0 rods with stock pistons and 4.2 crank.

[Cheromaniac]

If you were to reuse the stock pistons you'd definitely need a set of 4.2 rods. That said, I don't think it's a good idea to keep the stock pistons and bore size unless it's a low mileage block.

[tcervinsky]

would running the stock cam help reduce pinging? What about if someone were to use pre 96 cam, would it help reduce the need for "high" octane fuel or make performance suffer (or better)?

Reason I ask is because if someone were to use the 231 cam then you also need to change valve springs and related parts. Once you buy the pistons it's difficult to keep calling it a "poor mans" stroker. And that's what I thought he was building (not the 4.7L as he intended to over bore by 30, not 60.) Am I missing something else here?

[dragginwagon406]

That's why I'm still on the stock cam and lifters. I don't really think the cam is holding it back as much as the head flow (non ported) and throttle body (stock). I did deck mine but I've only run 93 and only have about 400 miles on it.

[martin809]

Thanks DIno, I was trying to save a few dollars. I know this is not a good idea when building an engine I am just getting impatient. I will break down and get the keith black 944 and have all machine work done.

I get discouraged when I see all the problems some have when doing this and start second guessing myself....is this a good idea?

[Cheromaniac]

If you want to really keep things simple and low cost while having newly bored cylinders, you could do the modified "poor man's":

4.6L modified "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith Black UEM-IC944-020 pistons
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.070" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, Accel 24lb/hr injectors with stock 49psi FPR for '96 and later engines

The only non-stock parts you'll need are the 258 crank, IC944 pistons, and Accel 24lb injectors.

[dragginwagon406]

Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, Accel 24lb/hr injectors with stock 49psi FPR for '96 and later engines

Why the Accel instead of Ford injectors for the 96 and later model engines? I haven't tied in my wideband yet to check, but the plugs look good...