Newb to here - questions

[UncleWally]

OK,

Been looking around on this subject for the last several weeks and finally found a forum for it. Thanks to those that started it.

I own an 84 CJ7 with a tired old 258. Been looking at what I will be doing to replace it. SBC is out of the question (I'm a Chevy guy from way back, but this isn't a Chevy, it's a Jeep). I'm not keen on the idea of a AMC V8, but I haven't ruled it out.

I called Bernie at Hesco and Golen Engine Service. Got some interesting information. I likely won't be spending the kind of money Hesco wants. I've heard some not so stellar comments about Golen. So I'm thinking I'll build this one myself.

My first question is:

What are the best parts to use and why?

Block casting number?

Head casting number? I've read the 7120 is a good one, albight doesn't flow well. The 0331is prone to cracking. So which one?

Crank casting number? What are the advantages of a 4cw vs 12cw crank? Are they all cast?

Rods? Stick with the 258 rods or use the 4.0 rods?

Pistons? Forged is what I'm looking for, who makes them to fit the rods of choice?

Cam? Looking for a off-idle to 4000rpm max cam -

Fuel injection system? I'm seriously looking at the Accel DFI Thruster for this for it's adjustability. Anyone use it?



As a note, I also want to use the v-belt accessories that I already have as with it is an old York Compressor that I use for On Board Air.

I'd like to start digging through the salvage yards for parts, so some good info on this would be greatly appreciated.

Waldo

[StroktWJ]

Block casting number?
1996-98 - 53020569, 1999-04-53010449, Do not get a 99-04 WJ block unless you want to fabricate mounts.... I'm not sure if it was the 96 or 99 blocks that started getting the extra material and webbing for more rigidity.

Head casting number? I've read the 7120 is a good one, albight doesn't flow well. The 0331is prone to cracking. So which one?
I believe 0331 was prone to cranking till 03. The 7120 or 0630 have the best flow numbers (unmodified)

Crank casting number? What are the advantages of a 4cw vs 12cw crank? Are they all cast?
The 4.2L crank snouts are longer except for the 727 casting so you will need the Hesco spacer/adapter if running serpentine, or a crankshaft machine shop would charge around $30 to cut the end down. They are all cast from what I have read, more weights is a smoother rotating assembly but you are also turning 8-10lbs more reciprocating mass.

Rods? Stick with the 258 rods or use the 4.0 rods?
I went with 5.875 rods and had the block decked .010 however it seems to be more common on this board to run the 6.123 rod. With the longer rod you will have less cylinder quench issues and have a broader power band.

Pistons? Forged is what I'm looking for, who makes them to fit the rods of choice?
Diamond are your best bet but big $$$,

Hope that helps, I cant answer all your questions but hopefully that is a start to a educational thread for you.

[dwg86]

Kieth Black makes an off the shelf forged stroker piston..kb944 and kb945. Use with the 4.0/6.125 rods.

[eastin82]

longer rod creates a better angle on the cylinder walls and leaves the piston at tdc longer. mine a 91 block going in a 81 cj5 doesnt have the extra webing but it was cheap and i opted to add a main bearing girdle like the 96+. you need external fuel pump and cps set up also.

[UncleWally]

Does anyone have pics of a 4cw and 12cw crank so I can tell them apart easily? I think I found a crank fairly cheap.

Waldo

[Muad'Dib]

Does anyone have pics of a 4cw and 12cw crank so I can tell them apart easily? I think I found a crank fairly cheap.

Waldo

Counterweights are counterweights... you can count them.

Check the casting numbers of the cranks also.. this will tell you allot.

viewtopic.php?f=27&t=51

[UncleWally]

Sorry - I guess I should have asked this a different way.

Is there a way to tell the difference in cranks without removing the pan? I guess I could go with the block casting number provided it hasn't been rebuilt.

Waldo

[dwg86]

I think up to 1980 are 12 wt cranks. From 1981 to 1988 are 4 wt. Here is a link to find out what engine you have...
http://www.vehicleidentificationnumber. ... -1980.html

[yuppiexj]

here's a 4CW viewtopic.php?f=8&t=444&p=8829#p8514
and a 12 CW http://www.angelfire.com/my/fan/stroker.html

Thanks SilverXJ and DIno respectively (both great contributors here.).