Which Crank?

[nate]

I'm gathering parts for a stroker 4.6/4.7L for my ZJ and I'm looking for advice.

I've been doing alot of research to build the best setup. Right now, I'm looking for a 258 crankshaft. I have a line on one (3214723 casting number) for $40.

The problem is I've been getting mixed reviews on the standard (3214723 casting) and lightweight (3235477) cranks. Which is the better choice?

A few sites say the standard (heavyweight) crank is better, since it's stronger, while I read a few posts on here that say go with the lightweight. What are the pros/cons to each?

 

[NCSUcherokee]

If you are gonna be running it with a manual tranny then you should run the heavier crank, it will lower the stall RPM by having more rotating inertia

If you are gonna run it with an auto then run the lighter crank, it takes less juice to get it to full spin because of the lower moment of inertia and stall isnt an issue because, well, its an auto

There are 3 cranks to choose from

1. 12 counterweight(3214723)- requires crank to be cut or a spacer fabricated

2. 4 counterweight(3727)- already correct length for serp. system

3. 4 counterweight(3235477)- requires cut or spacer

most run 1 or 2 depending on transmission

edit- casting numbers pulled from Dino's site http://www.angelfire.com/my/fan/stroker.html

 

[Dr. Dyno]

The 12-counterweight crank seems to be the most popular and I think that's because there's more of them available. The extra counterweights do smooth out some of the harmonics and this crank has reputedly been used by racers with no reported failures.
The lightweight cranks have 4-counterweights, are 20lb lighter, and allow the engine to rev up faster so theoretically, they should be good for a stroker that's built for higher rev HP. The only problem is that harmonic resonance becomes more of an issue at higher rpm because there are fewer counterweights to dampen it.
Since you have a line on a 12-counterweight crank, go for it as long as it's in good condition. You'll need to have it checked for cracks and the journals may need to be reground if they are scratched or "out of round". To further aid smooth operation, you have the option of getting the crank spin balanced at a machine shop.
As an alternative, you could buy the 258 crank & rods through e-bay from Atlanta Crankshaft Exchange:

http://search.stores.ebay.com/searc...t+Exchange&colorid=14&fp=0&st=1&submit=Search

I bought my crank from them. It was very neatly packaged and it looked great. Their products and customer service are top notch and I highly recommend them.

 

[nate]

I am running an auto.

I didn't realize it was a 4 counterweight shaft. The webpages I read said the cranks were all either 8 or 12.

It looks like all the stroker kits use the 4 counterweight cranks. Must be a reason? I would like an engine with good torque, but to also be able to "spool up" quickly, seemed like the lighter crank would do that?

I have no problems with the low end power of my 4.0, it just turns to a complete turd trying maintain 60-70mph.

 

[Dr. Dyno]

It looks like all the stroker kits use the 4 counterweight cranks. Must be a reason? I would like an engine with good torque, but to also be able to "spool up" quickly, seemed like the lighter crank would do that?

Yes, and that's probably the reason why the stroker kits have the 4-counterweight crank. You can't ignore a 20lb weight saving over the 12-counterweight version.

 

[nate]

Thanks!

 

[old_man]

For low rpm wheeling, especially with a manual tranny, the heavier crank is definately better. I run one. Yes it won't wrap as fast, but I don't care. It is still a dream to drive.