stroker noob questions for 94 YJ

[agalloch07]

I have owned my 1994 YJ for 23 years and have been building it since the day i bought it. It has RE 4.5" lift, 1.25" body lift, NV4500 transmission, NP231 i went though and put a wide chain and 6 pinion planetaries in. I put custom Dana 489's in it from ECGS with OX Lockers and 4.88 gears. The jeep is not a daily driver more of a toy but i would like a bit more power so i am thinking about building a stroker engine. Right now the performance mods i have are all bolt on stuff. I am still running the stock air box and filter because i take this offroad and i do not want to run an open element filter or a K&N.

Doug Thorly Header
JBA head pipe
no cat
Borla cat back
MSD coil
8mm plug wires

I want to keep the build relatively cheap but i want it to be as reliable as a stock 4.0 and run on pump gas. I am wanting to start figuring out some parts i should buy. I guess Scat cranks are pretty much standard now that 258 cranks are getting scarce? Years ago i had 2 258 cranks i was saving for a future stroker build but i got tired of them sitting around and ended up letting a friend have them for scrap metal.

I want to run good rods and i dont mind paying for forged i have seen Scat forged rods for about $300 are they worth it in the long run?

I was planning on using Keith Black pistons but i have read a few posts here about Ross Pistons so you dont have to deck the block is Ross way to go?

And will i need any type of tuning or just put some 24# injectors in it?

[Russ Pottenger]

Welcome to the forum,

Stroker builds and packages have come a long ways in the last 10 years or so.
Similar story to yours is one of the crank grinders that I deal with told me that he was scraping 258 cranks 15 years ago, and in just the last few years it’s getting harder to find 232 cranks for guys wanting to go the “Mini Stroker” route.

I have stroker packages that include Multiple dish volume piston choices and compression heights that give you the cost saving option of not having to deck the block that’s matched up with my affordable bushed steel rod that again gives you the option and convenience of the cost savings of not having to rely on your machine shop to press your pistons on for you.

The days of the press fit KB 944 pistons in stroker kits are slowly becoming obsolete packages.

Feel free to contact me I’ll be more than happy to email you some information and pricing of my kits and cylinder head porting services.

Thanks,
Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Cell (626) 673-2203
Email: [email protected]

[Cheromaniac]

The Jeep I6 stroker game has indeed changed quite a bit since I built my poor man's stroker 16 years ago. Used original 258 cranks are becoming as rare as hen's teeth and, as Russ rightly pointed out, even the 232 cranks are becoming scarce. To think that I bought my 12cwt 258 crank for about $75 in eBay all those years ago. A Scat crank is pretty much the only viable option now.
That said, custom forged pistons & rods are more reasonably priced now than they were back then, and there's now a wider range of other stroker parts available. It's quite ironic that despite the production of the 4.0L I6 engine being discontinued 14 years ago, it's easier than ever to build a great running stroker engine and Russ can take a huge amount of credit for that.

[agalloch07]

Welcome to the forum,

Stroker builds and packages have come a long ways in the last 10 years or so.
Similar story to yours is one of the crank grinders that I deal with told me that he was scraping 258 cranks 15 years ago, and in just the last few years it’s getting harder to find 232 cranks for guys wanting to go the “Mini Stroker” route.

I have stroker packages that include Multiple dish volume piston choices and compression heights that give you the cost saving option of not having to deck the block that’s matched up with my affordable bushed steel rod that again gives you the option and convenience of the cost savings of not having to rely on your machine shop to press your pistons on for you.

The days of the press fit KB 944 pistons in stroker kits are slowly becoming obsolete packages.

Feel free to contact me I’ll be more than happy to email you some information and pricing of my kits and cylinder head porting services.

Thanks,
Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Cell (626) 673-2203
Email: [email protected]

I remember years ago about having to dish pistons but it was so long ago i dont remember the details of it all. I have never built an engine before so this is all new to me so if i am wrong on something i would like to be corrected. But as far as my understanding goes is that for a daily driver the pistons are better off being cast rather than forced because of expansion rates and the fitment of the piston in the bore. So i am guessing the pistons you sell are cast?

As for rods i am more lost but i have seen rods go though he side of the block on stock 4.0's. So my thinking is i want a rod that is stronger than stock just to prevent that from ever happening. I see that the Scat forged rods are only $300 but as far as pressing them on i have never done that. When i took apart the 258 in my old 77 CJ7 the rods looked really weak and appeared to be made out of cast aluminum. Are your steel rods stronger than stock?

I dont want to go super cheap i just dont want to go crazy expensive like the $6,000 Golen strokers. I would rather keep it around $3,000 or less.

And is a 4.7 stroker with the proper cam, injectors, quench height tolerances ect... capable of putting out 300HP with the stock ECU? I am fairly happy with my stock 4.0 but after adding 35's even with 4.88 gears i would like to get some more power out of it but i still want it to be reliable. And i really dont want to have to run aftermarket fuel injection and have to deal with tuning it.

[SkylinesSuck]

+1 for Russ moving the stroker game forward by leaps and bounds!

[Cheromaniac]

And is a 4.7 stroker with the proper cam, injectors, quench height tolerances ect... capable of putting out 300HP with the stock ECU? I am fairly happy with my stock 4.0 but after adding 35's even with 4.88 gears i would like to get some more power out of it but i still want it to be reliable. And i really dont want to have to run aftermarket fuel injection and have to deal with tuning it.

4.7L medium-buck stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom forged +0.060" bore pistons, compression height 1.380", dish volume 15cc
10.2:1 CR
CompCams 68-235-4 210/218 degree camshaft
Russ Pottenger ported Edelbrock 60cc aluminum cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Flometrics F&B 68mm billet TB
Accel 30lb/hr injectors for '87-'95 engines
290hp @ 5100rpm, 340lbft @ 3700rpm

A 300hp stroker is certainly doable. This is a recipe I have on my site, and the bigger CompCams 68-239-4 cam with a slightly higher compression ratio will get you there.

[Russ Pottenger]

Hi Nick,

Good talking with you over the phone. As per our conversation I’ll happily forward you pricing and information on a recommended kit based on your application and budget

Thanks,
Russ

[agalloch07]

Hi Nick,

Good talking with you over the phone. As per our conversation I’ll happily forward you pricing and information on a recommended kit based on your application and budget

Thanks,
Russ

lol, i am not Nick but i think your talking about a friend of mine who is building a stroker and told me he called you to ask questions. He is the one currently building a stroker and now has me wanting to build one as well. We are both researching the best way to build a stroker without spending a fortune but at the same time do it right the first time.

His YJ is a 1992 if i remember right and hes building a engine out of a 1995 YJ parts jeep. It's one of the quirky late production YJ's that have the TJ style windshield bumpers on the hood and aluminum tailgate hinges. The engine also uses the stamped steel valve cover like TJ's had so we are wanting to find out if it is a 7120 or 0630 head. We spent the day pulling the engine/tranny/t-case out of the parts jeep and just didn't get around to cleaning up the head and seeing what casting it was.

[Russ Pottenger]

Gotcha.

Thank goodness my cylinder head porting skills are better than my clerical.

[agalloch07]

Gotcha.

Thank goodness my cylinder head porting skills are better than my clerical.

lol! Nick is thinking about running the aluminum edelbrock head with bigger valves and all the bells and whistles. I think i will stick with my '94 7120 head and have it ported how much do you charge for head work? Since i am a engine performance noob i dont even know what i would need or want and if bigger valves will even benefit me. My jeep is built for off road so i think i would rather go with low end torque than high end HP so i dont know if that kind of work would benefit me much.

I am content with the power my jeep has i dont think it's a dog but 300hp sounds nice. My 4.0 only has 120K on it and i have maintained it very well so i have always been a bit apprehensive of throwing away it's reliability chasing HP and ending up causing other unforeseen problems. But once Nick gets his built I'm sure i will want one so I'm starting to plan a build as well.

[Russ Pottenger]

My ported Edelbrock head with my custom Edelbrock dish piston makes for a good package, but for about half the cost I could do a a 7120 LS valve head for you that’ll easily put you in the 300hp club.

Shoot me an email I’ll be happy to send you some pricing information.

[agalloch07]

I was recently thinking about buying some roller rockers to run on my jeep in the meantime while i think if i am going to go ahead and build a stroker. But i have some questions if i can even run them on the stroker if and when i build it.

If i do end up building it i want to have head work done so i can run a bigger cam. And while shopping for roller rockers i was looking at Harland Sharp rockers on Summit Racing. I assume i would want to stick with the 1.6 ratio rocker just so i dont complicate things since it would be getting a bigger cam i dont really need the valves to open up anymore than with all the machine work i would be having done to it , correct me if i am wrong.

Then they have stud options the stock 5/16 and larger 3/8". I am assuming that the added stress of larger Chevy springs would require a bigger stud to keep the stud from breaking due to added stress of more spring tension. So if i were to go ahead now and buy 5/16" rockers i would be throwing money away since i would need 3/8" studs with the chevy spring/valve work. They also ask about valve spring diameter and if it's stock or 1.420 in. I assume they are talking about chevy valve springs again.

And finally if they should be adjustable or non adjustable. Does it really matter? I thought hydraulic lifters didn't need adjustment int he first place?

[Russ Pottenger]

Your rocker arm ratio will be somewhat decided on which camshaft that is chosen.

You do not want to drill out the pedestal for a 3/8 stud.
You’re just gonna weaken the overall column strength of the pedestal and it’s just not necessary.

If you have somebody like myself do the cylinder head, the non-adjustable’s are fine. If the tip heights are set properly and you’re running a hydraulic lifter you’re good to go.

Again if you contact me I should be able to give ya good Harland Sharp pricing and advise you on the ratio and camshaft selection

[agalloch07]

Your rocker arm ratio will be somewhat decided on which camshaft that is chosen.

You do not want to drill out the pedestal for a 3/8 stud.
You’re just gonna weaken the overall column strength of the pedestal and it’s just not necessary.

If you have somebody like myself do the cylinder head, the non-adjustable’s are fine. If the tip heights are set properly and you’re running a hydraulic lifter you’re good to go.

Again if you contact me I should be able to give ya good Harland Sharp pricing and advise you on the ratio and camshaft selection

If i do a stroker build i plan on using your kit and have you port my head and put bigger valves in it. I dont know what cam i will be using because i have not gotten that far and i dont know the first thing about choosing a cam. My friend Nick has been doing a lot more reading on this subject than i have.

I was looking at the email build sheet you sent and ended up asking nick if it was the same cam he was originally going to use. He said it was not the same one he kept reading about when he was looking at the engine builds done with KB pistons (and no head work). When i was comparing the specs of both cams i noticed that the cam on your build sheet had more lift than the cam he was originally planning on using. And i assume thats because you machine the head to use chevy valve springs so you can run a bigger cam with more lift?

So i guess i will be using the cam you emailed me unless you think i might need a different cam for some reason. I am a noob at all this and im probably asking way to much but i would like to have a reliable 4.7 pushing 300hp and still get somewhat decent mileage if i keep my foot out of it. I dont know if this is possible and i know im going to take a gas mileage hit but i just hope i dont have to start carrying spare gas cans in my jeep lol. The local machine shop we talked to several weeks ago recommended having a custom grind done because we could have it custom made to our particular individual application. Not saying i am sold on a custom grind it's just what he told us.

So if i went with the cam in your build sheet along with your head work would i need 1.6 or 1.7 rockers? I will order them through you im just using summit racing to compare options and learn about the differences in specs and what would work better.

[Russ Pottenger]

I can cover allot more information if you call me.