bored .040 engine questions

[mcantar18c]

Well i did some research and it turns out i have the 242 crank....so no 4.2 stroker cranks......Damn.....but hey no biggie im sure i can find the crank im a junk yard....

Speaking of which Exactly what did the 258 crank come out of? Ya know the one with 4 counter balences.

Uh... the 258 crank is out of a 258. The 242 crank is out of a 242. Those are the displacements of the engines. 258=4.2, 242=4.0, Chevy 350=5.7.

If you're asking what the 258 engines are in... CJs, early YJs, etc... it looks just like a 4.0 with a carb on it.

 

[bails85]

not to be off point but most engine builders i have talked too dont reccomend boring in a 4.0 to be over .030 because it will thin out the cylinder and the engine will run hot. not 100 percent sure on that info but maybe something to research.

 

[vortex]

not to be off point but most engine builders i have talked too dont reccomend boring in a 4.0 to be over .030 because it will thin out the cylinder and the engine will run hot. not 100 percent sure on that info but maybe something to research.

Look through the quoted article and you will find that you can bore out to .060 if you botch something so i believe .040 will be a good place......http://www.naxja.org/forum/showthread.php?t=1032246&highlight=stroker+crank+casting+numbers

And about the CJs and YJs....what years would i be looking for?

And Matt i will give you a call when i can.....

 

[cruiser54]

1970 to 1989?

 

[mcantar18c]

And about the CJs and YJs....what years would i be looking for?

Pre-91 YJs, post-72 CJs, and I think some post-71 Waggys.

And btw, you're fine boring it .040.

 

[vortex]

Pre-91 YJs, post-72 CJs, and I think some post-71 Waggys.

And btw, you're fine boring it .040.

Most excellent.....In i know im fine boring .040 but thanks for the reassurance....

 

[mcantar18c]

Most excellent

:roflmao::roflmao::roflmao:
http://www.youtube.com/watch?v=OT4B-NJUcZE&feature=related

 

[vortex]

:roflmao::roflmao::roflmao:
http://www.youtube.com/watch?v=OT4B-NJUcZE&feature=related

haha thats was funny...

 

[AIbandit]

www.jeepstrokers.com has all the info you need, from 258 vehicles to what you need/ should do to get a reliable stroker.


also you may need to go over .040 the water pump cools the first cylinder and causes alot of wear (according to my machinist). It definitley shows more wear than the rest of the cylinders.

 

[mcantar18c]

haha thats was funny...

Lol well the last time I heard anybody say "most excellent" was that movie. Had a good laugh when ya posted it.

also you may need to go over .040 the water pump cools the first cylinder and causes alot of wear (according to my machinist). It definitley shows more wear than the rest of the cylinders.

Huh? Not sure I follow what you're saying... could ya explain a bit?

 

[AIbandit]

If you run your finder along the inside of your cylinder wall you can feel a lip if its worn it was more prominent on my first cylinder on the opposite side of the wall sits your water pump. he said the water flowing directly to that spot causes that.

 

[mcantar18c]

Interesting... never heard of increased runout caused by a water pump. Doesn't really make much sense to me, I'll have to look into that a bit.

 

[DieselSJ]

also you may need to go over .040 the water pump cools the first cylinder and causes alot of wear (according to my machinist). It definitley shows more wear than the rest of the cylinders.

You need to find a new machinist.

 

[AIbandit]

He may be tarded but he does good work
I just know he's seen the inside of more 4.0's than I have. May not make him right in reasoning but I'll give him the benefit of the doubt for atleast identifying a trend.

 

[vortex]

that is interesting.....

 

[mcantar18c]

I don't see how increased water flow --i.e. increased cooling capacity-- in a specific area would cause an increased amount of wear on the cylinder wall. In fact, I'd guess that just the opposite is true.

 

[jeeperjohn]

I personally would not replace just one piston. Since the engine is already torn down I would get a matched, balanced set of pistons and have the rods checked/balanced. I would also take the whole rotating assembly and have it balanced as an assembly. While you're at it you might as well stroke it right?

 

[vortex]

I personally would not replace just one piston. Since the engine is already torn down I would get a matched, balanced set of pistons and have the rods checked/balanced. I would also take the whole rotating assembly and have it balanced as an assembly. While you're at it you might as well stroke it right?

For sure....shouldn't be too terrible....

 

[Talyn]

BTW, that number on top of the piston might not be its over size. I had a set of pistons that said 50 on top. But they were .030" over pistons.

 

[stroked88]

I don't see how increased water flow --i.e. increased cooling capacity-- in a specific area would cause an increased amount of wear on the cylinder wall. In fact, I'd guess that just the opposite is true.

it cools that one spot more than the rest of the cylinder and causes uneven cooling and causes the cylinder to disform slightly due to the metal expanding different amounts. atleast thats what im imagining out of it :dunno: