258 crank into 4.0. Is it that easy?

[Masato]

To get a 4.6 or 4.7, is it just a matter of swapping in a 4.2 crank into a 4.0? I know nothing about 4.0s

[Cecil14]

For the most part. The 4.0 block is almost identical to the 258/232 blocks. There shouldn't need to be any machining done.

You can use either set of rods (258 or 4.0) but with each you have to use a different set of pistons. If you use the 258 rods you just use stock 4.0 pistons for whatever bore you've got. (I had to have my 4.0 block bored .060" over and got stock 4.0 replacement pistons in that size.)

If you use the 4.0 rods you have to use custom pistons which can get fairly expensive but can lower the compression ratio down to whatever you want it. (With the 258 rods and 4.0 pistons compression is suppose to be upwards of 9.7:1 :eek: .)

Any other q's?
Anthony

[J10/J20 Project]

you will need the connecting rods also. you can either make a 1/4 spacer for the harmonic balancer or have a shop take off the 1/4" at the end of the crank. There are some good write ups on this.

[ March 18, 2003, 08:26 PM: Message edited by: J10/J20 Project ]

[Masato]

So all the brackets (alt, P/S, etc)from the 4.2 will fit?

What about the fuel pump, does it have a mechanical one or do I need an electric pump?

Augusto

[Cecil14]

There is a basic writeup on my homepage. I need to add a few more things but that's got the jist of it. For the balancer it depends on what your run. If you run the stock 4.0 stuff (FI, serpentine belt, etc.) you need to either have the 4.2 crank snout machined down or get the spacer as mentioned. If you use the stock 4.2 stuff (carb, v belts, etc.) then you don't need a spacer, just bolt on your balancer.

All the brackets will bolt on to the 4.0 block. The only thing we had an issue with is the power steering bracket. If you use a carb you have to move the intake up about a 1/2" or so to cover up the injector ports on the 4.0 head. Because the power steering bracket bolts to the intake this moves everything and some of the bolts don't line up. We also had to clearance the back of the bracket to get around the header pipe. I'm going to make a different bracket for the power steering that should relocate everything back to where it's suppose to be. I'll put a short writeup on my page when I get that far.

As for the fuel pump, the 4.0 block doesn't have a provision for a mech. pump so you have to run an electric one. What kind you run depends on if you run FI or a carb.

Anthony

[Masato]

Anthony,

Where is your homepage? I clicked the link for your Wrangler but couldn;t find the writeup for the stroker.

I have some more questions, but would like to read it before asking.

[Cecil14]

Sorry, it's www.geocities.com/cecil_odo (http://www.geocities.com/cecil_odo)

I just updated my sig, now it should take you to the first page.

You can email me if you've got any specific q's.

odo@myownemail.com

Anthony