Not quite getting it. Need info in lame-@ss terms.

[Arizona YJ]

I get the general idea and I want to do a budget stroker. I have been thinking of dropping in a SBC since I already own it. The cost will be about the same to go V8 as stroker I think.

I have a older 258 complete for free. It should have the good rods from I am reading here. I was worried about main and rod journal sizes and got confused on the issue.

Is the 258 crank the same rod/main size?

If I am using the 258 crank and rods, what innexpensive pistons can I buy. Cast should do fine but silvolites would be nice I guess.

What about one peice main seal vs two peice on the older block.

My jeep is a 92 YJ with 4.0L and AX15 five-speed. No mods so far.

Please help to unscrew my brain on this. Sorry if this has been answered already but I was not having any luck with a straight-up answer.

[Arizona YJ]

Oh yah....

looking for a 0.030 over bore and a pump gas motor. Looking into newer intake/TB/injectors as well.

[1bolt]

I would recommend absorbing some more info take your time and read up. if you're in a hurry I guess that's a problem, but the more you read on the subject the happier you'll be in the long run.

In the simplest terms, the 258 crank works as a drop in replacement, either 4.0 or 4.2 rods fit without problem but getting a good compression ratio and quench requires the right combination of rod and piston. Compression ratio and quench are the primary ingredients that determine how well your engine will do long term and short term. Too much of either will have you playing an expensive game of trying to eliminate "ping".

If you don't understand that much about those two things then either learn about them or follow one of the recipies that fall in your budget and goals. And don't worry too much about them.

The 350 chevy can be cheaper (It and a drive train are sitting in your yard already) or a whole lot more expensive... there are pros and cons either way. The usual points apply here, the Stroker I6 will out torque a garden variety late model 350, the 350 will be cheaper to hop up and has more upper end potential cheaper aftermarket parts etc.. The stroker bolts in and plugs up to stock everything, the 350 requires wiring, trans, cross members, transfer case, drive shaft front and rear, motor mounts, or expensive adapters.

[Arizona YJ]

I appreciate the response and agree that I am a little ignorant to say the least on this topic. This is a daily driver. The V8 would be rather easy for a minimal gain. The adapters are about $500 if purchased, $350 for the trans adapter only. That would bolt it to my AX15 and my frame. Running a carb would be cheap but FI would be required at some point.

I want to avoid building a stroker and doing a crappy job by being cheap. I dont need a powerhouse but would like the gains of the stroker over a stock rebuild since the machine work would be about the same ( in think). I will look again at the recipe thing.

I pretty much want to be able to drop-in my crank and rods and put in a piston that works. I have been reading and it seems that there are pistons available that would work. Like you said, i have no clue about the quencch thing.

Is there such thing as a piston that can be purchased as-is without extra cc work to get the right numbers?

[amcinstaller]

the rear main seal is only available as a two piece set. (there is two styles for different vintage of block, one has "shoulder" type things stickin out one doesnt. maybe the latter has two seals??) but the two piece design is due to the size of the crank arse end where you mount the flywheel/flexplate im guessin.

any reason youre gunning for a .030 overbore?? i was goin for a .040, but was talked out of it by my machinist. dont think youre dumb, just askin why.

and the only "stroker specific" type pistons ive heard of are keith blacks, couldnt tell you the part number (and ill probly be flamed for that ) but alot of people here know about them. but those are one dish, and i believe oletshot here can dish them for you.

[Arizona YJ]

Only because 0.030 seemed like a good number since it gets me some more cubes but leaves room for future rebuilds. I dont plan to sell this jeep pretty much ever so I want a long term motor.

[Heck]

The keith black 944 piston and ring package (kb944030uem) cost around $550, but I thought they were worth it because they are top quality, forged, use the longer 4.0 rods, and the quench comes out just right. Well worth the cash. Took a lot of worry, math, and guesswork out of my stroker.

[Arizona YJ]

That sounds like the ticket. Did you have to cc the pistons or head and what about the deck?

[Exos]

KB944 have a 21.7 cc dish. They are meant for 4.0 stock rods. Decking to zero will bring your quench to whatever gasket thickness you choose. Quench beeing the height from top of piston (flat part) to bottom of head.

[Arizona YJ]

Awsome..... You guys rock. I hope that this thread helps someone else out besides just answering me questions.

I guess the only other question I have would be.......


TA-DAA!!

What thickness/maker/whatever would be appropriate with:
258 crank
4.0L rods,
4.0 block zero decked
KB944 pistons.

Aiming for about 9:1 -9.5:1 compression. I know in SBC that's a nice range number for a mild motor so that was my thinking for this project.

[gradon]

The block will have to be decked ~.030" with the KB&4.0 rod setup to get the 0 quench, fyi.

[SilverXJ]

Check out my build thread in projects. I am just finishing up an engine similar to what you are planning.