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what style of 4.2 crank?

Posted: April 14th, 2008, 5:04 pm
by 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 :mrgreen:

Re: what style of 4.2 crank?

Posted: April 14th, 2008, 5:23 pm
by 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 :huh:

Re: what style of 4.2 crank?

Posted: April 14th, 2008, 6:03 pm
by Muad'Dib
Chris wrote: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 :huh:
This seems to be the general consensous...

viewtopic.php?f=27&t=51

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

Re: what style of 4.2 crank?

Posted: April 14th, 2008, 6:21 pm
by 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.

Re: what style of 4.2 crank?

Posted: April 14th, 2008, 6:38 pm
by 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. . .

Re: what style of 4.2 crank?

Posted: April 14th, 2008, 10:24 pm
by gradon
I'm even scheming on a light-weight flywheel, so you know who I have to give a call to. . .

Re: what style of 4.2 crank?

Posted: April 15th, 2008, 12:14 pm
by seanyb505
Ghostbusters?

Re: what style of 4.2 crank?

Posted: April 15th, 2008, 2:35 pm
by gradon
ha-ha-hesco

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 11:00 am
by Cheromaniac
4.0l sahara wrote: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 :mrgreen:
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.

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 12:20 pm
by seanyb505
gradon wrote: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."

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 2:48 pm
by 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).

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 6:44 pm
by stroked'73
gradon wrote:ha-ha-hesco
Don't Hays, Ram, Centerforce, etc. all make aluminum flywheels also?
Moneywise they're probably all in the same ballpark, though.

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 6:54 pm
by gradon
Centerforce makes one for an older model jeep IIRC--I'll search around and let y'all know what I found.

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 8:14 pm
by Shark
ill take a 4cw if anyones got an extra.

Re: what style of 4.2 crank?

Posted: April 16th, 2008, 9:31 pm
by 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).