what style of 4.2 crank?

[4.0l sahara]

I know that there are two styles of cranks used in the 4.2 . Am I right that the 12cw crank is better? why?

Thanks

[Chris]

The way I understand it, the 12w is better for low torque low speed applications such as rock crawling. The reason is it has more weight, so once it gets to spinning, it is harder to slow down...aka - momentum. The lighter ones will rev quicker, and are more for high speed applications. I don't think there is really much of a noticeable difference though. I could be wrong on this, but I read it somewhere, so

[Muad'Dib]

The way I understand it, the 12w is better for low torque low speed applications such as rock crawling. The reason is it has more weight, so once it gets to spinning, it is harder to slow down...aka - momentum. The lighter ones will rev quicker, and are more for high speed applications. I don't think there is really much of a noticeable difference though. I could be wrong on this, but I read it somewhere, so

This seems to be the general consensous...

viewtopic.php?f=27&t=51

Although when i build mine im going to try the 4cw.

[seanyb505]

As far as strength goes I have yet to read that either has an advantage/disadvantage. I have read that the 4wt is more vibratious. No real world experience, give more 3 months Ill let you know.

[gradon]

I wanted less weight and faster spool-up so that's why I traded a 12cw for a 4cw. I'll find out in a month. . .

[gradon]

I'm even scheming on a light-weight flywheel, so you know who I have to give a call to. . .

[seanyb505]

Ghostbusters?

[gradon]

ha-ha-hesco

[Cheromaniac]

I know that there are two styles of cranks used in the 4.2 . Am I right that the 12cw crank is better? why?

Thanks

Each has its own advantages but in the real world, either will do very well:

12CW: Less vibration (more counterweights), extra 20lb like having a heavier flywheel (engine doesn't stall when rockcrawling at very low revs), better choice for endurance racing.
4CW: 20lb less weight over the front wheels, engine revs up faster, better choice for drag racing.

[seanyb505]

ha-ha-hesco

Youll have to switch to an auto trans type starter. Taken from Hesco - "The flywheel does not come with a ring gear and is designed to be used with a automatic flex plate that will match your existing electronics..." "May also be used with manual transmission using an automatic transmission starter ring to complete installation."

[gradon]

Yeah I went to Hesco's site months ago and saw the auto-flexplate, but thought there was a different p/n for the manual-flywheel since I had read comments about it from somewhere(I'm gonna hold off before I drop $350).

[stroked'73]

ha-ha-hesco

Don't Hays, Ram, Centerforce, etc. all make aluminum flywheels also?
Moneywise they're probably all in the same ballpark, though.

[gradon]

Centerforce makes one for an older model jeep IIRC--I'll search around and let y'all know what I found.

[Shark]

ill take a 4cw if anyones got an extra.

[gradon]

No luck on the light-weight aluminum flywheel. I did shoot an email to Fidanza. They make light-weight aluminum flywheels and have a HD 39# steel one for our 4.0s so they might be able to make a light-weight one. Some of their flywheels weigh 13-18#s, which would be nice. I also googled "custom flywheel" and shot an email to a JB Racing(IIRC) in Florida. Since I have to wait on the pistons and block work, I'm tempted to give Yella Terra a call(I'm not sure I want to reuse the stamped rockers-esp with the additional lift of the 30ab).