Jeep Strokers

Ok so I'm planning my build for my 97 XJ's 4.0 to do a 4.7. I want to run 87 and have been picking Russ Pottenger's brain a lot and I want to run the KB 2229C-060 pistons dished to 28cc and run about .040 quench.

I've gotten mixed opinions between using the 4.0 rods or the 4.2 rods. Can anyone give me some insight?

keep searching. im running the 4.2 rods because that's what i got. its a budget thing for me, if i went to 4.0 rods, i'd go to custom pistons which is more money. im going the 42.crank/rods route. dished pistons P&p head. building for 87 octane and a daily driver. there are so many ways to get where your going. i think the question is, where are you going with your build, and how much do you want to spend on it. btw im pretty new at this too, search the forums, for hours on end. if your planning on running russ' 2229's, your already on a 4.2 rod build. stock 4.0 pistons on 4.2 rods with a 4.2 crank. 4.2 crank 4.0 rod with a stock 4.0 piston doesn't work. look for dino's 4.0 performance site.

if you punch it 60 over you are at the maximum bore, which means you have to have the walls sonic tested from what i have learned. im going 30 over to avoid getting that close to the limit and spending money needed to push it that far.

If you are doing to use the Silvolite 2229 pistons you need to use the 4.2L rods.

ben824 wrote:Ok so I'm planning my build for my 97 XJ's 4.0 to do a 4.7. I want to run 87 and have been picking Russ Pottenger's brain a lot and I want to run the KB 2229C-060 pistons dished to 28cc and run about .040 quench.

I've gotten mixed opinions between using the 4.0 rods or the 4.2 rods. Can anyone give me some insight?

If you already have a set of 4.2 rods, then just get the UEM-2229s dished to 28cc as planned and run them.
If you have to spend money to buy a set of 4.2 rods, don't bother. The longer 4.0 rods would be more desirable and since you already have them, you'd only need to buy a set of Bulltear custom pistons and spec them with the same dish volume.

Don`t like using the shorter 4.2 rods for one important reason. At BDC the piston is pulled too far out of the bore.

jsawduste wrote:At BDC the piston is pulled too far out of the bore.

I agree that more piston comes out of the bore at BDC than is ideal but there's still enough piston inside the bore to maintain its stability under normal everyday use. However, sustained use at high rpm could break the skirts so I'd reserve the shorter 4.2 rods only for mild strokers that'll rarely see 4500+rpm and even then, only if you've recycled them from a 4.2 engine that's already in your possession so you won't have to spend money to buy a set.

I do not yet have the 4.2 rods but when I talked with Russ and told him what kind of motor I was looking for his combo included using the 2229 pistons and the 4.2 rods. I was originally thinking of buying his engine but that proved too expensive being my budget is $4000 and that includes paying someone to pull the engine, rebuild it with parts and labor, and then put it back. Russ's engine was going to be $3750 shipped which didn't leave me hardly any money to have it put in. Basically I couldn't afford Russ even though it would have been worth every penny. So at this point I want to try and copy what he would have built with a local engine builder.

A builder that is about 40 minutes away can build it but had never done a Jeep engine but he has done almost every other powerful V8 out there. He also does not pull the engine, but he recommended using the 4.2 rods as well.

I talked to another guy about 2 hours away that came recommended over on NAXJA SEC chapter who rebuilds Jeep strokers as well as does many other off-road work and he said he likes using the 4.0 rods better.

So I'm torn between the guy who only does engine building but doesn't have first hand experience or the guy who has first hand experience but his main business isn't doing engines but a little bit of everything.

And they both have different opinions on which rod to use.

I agree with both John and Dino who I both greatly respect. Just a couple thoughts to expand on what points they already made.

So many times it comes down to application and budget.
I'm having different but similar conversations with two customers on crankshafts much like the piston and connecting rod scenario.

So this is how it go's. A customer approaches you/me to build a 4.6, 4.7 Stroker. He has nothing, just a high mileage 4.0
running engine that's going to be the starting platform for Stroker project.
To simplify the discussion we're just going to talk money not application. Like I said my customer has nothing.

So we need to buy a crankshaft from me or someone else. I have about a dozen or so OEM 258 cranks (and 232) both 4 and 12 counterweighted. I've payed as little as $50.00 and as much as $200.00 a for 258 crankshaft. After we buy /sell the crank we need to clean, mag and most likely grind it. After that we balance it. If it has the long snout I'll have to sell him one of my spacers.

I have 5 Scat cranks on the shelf that sell for around $400.00. Now depending on what you need and want to have done on the used take out 258 crankshaft, you'll be at or within a hundred bucks of the new Scat crankshaft.

Another conversation can be had on the merits of buying a Edelbrock head or putting some love into your HO head you already have. These discussions are goin on in another thread on this site.

Lastly I'll close with this thought. Thank God we have guy's like Dino that have taken the time to compile and condense
allot of simple and easy to understand information that creates a basis for these conversations to start.

Russ

Russ Pottenger wrote:Lastly I'll close with this thought. Thank God we have guy's like Dino that have taken the time to compile and condense
a lot of simple and easy to understand information that creates a basis for these conversations to start.

Thanks Russ. I wasn't expecting a compliment like that.
It's thanks to guys like yourself who shares his own knowledge and experience that I'm able to assimilate information on my site for the benefit of others.

Ok Russ so let's say I retain my stock 4.0 rods with the 4.2 crank, what piston would I go with and what would my combo be to run 87 pump and keep a tight efficient quench? And by retaining the 4.0 rods with a .060 overbore will I still be at 4.7 displacement?

ben824 wrote:Ok Russ so let's say I retain my stock 4.0 rods with the 4.2 crank, what piston would I go with and what would my combo be to run 87 pump and keep a tight efficient quench? And by retaining the 4.0 rods with a .060 overbore will I still be at 4.7 displacement?

I'd go with custom Bulltear pistons to set a compression ratio of ~9.3:1 with zero deck clearance (0.043" quench with same thickness HG). Dish volume will be ~28cc and the compression height at 1.380". With a +0.060" overbore, the displacement will be 4657cc (4.7L).

Ben,
Another option is if you went with one of my heads I could get chamber out to 64cc.
Zero deck, .043 gasket, and shelf 944 pistons you'll be at 9.27:1

So many choices.



Russ

Russ Pottenger wrote:So many choices.

Yeah, much like in this video:

www.youtube.com/watch?v=PfDoDWlSp1o

I am running a 4.0 block, bored 30 thou and decked, with a 40 thou quench.
We used a 4.2L crank and a 4.0 rods. The difference in the rod length and crank throw meant that we used Keith Black Icon IC944 forged alloy pistons, which compensate for the longer throw and their short profile gives faster spin-up. The downside is that with minimal skirts, they draw less heat from the combustion chamber, which in turn means you need to consider improved cooling over stock.

I also used Harland sharp roller rockers and a Comp Cam Extreme 4x4 cam. In the case of both the crank and the rockers, you will need to pay attention to clearances and machine as required to get prudent clearances.

PS: The KB pistons compensate for the 4.2 crank's longer throw by having a higher pin height. The machinist that was doing the work milled the pistons for valve clearance/relief.