4.2L or 4.7L conversion

I am getting ready to pull the motor out of my 89' Laredo and am looking at adding some umph to it. To up my current 4.0L to 4.7L or 4.2L, what is involved.

For 4.2L I know I need a 4.2L camshaft. What would I need to do to the head, cylinders and such. What about for 4.7L.

I think you have some ideas confused. The 4.2 is a different motor unless you just plan to overbore the 4.0L to get a 4.2L which I don't think it possible.

The 4.5, 4.6, 4.7, 4.9 stroker motor requires the use of a 4.2L crank.

You will need a good amount of machine work on the block and head. You have a lot of options for pistons, camshafts, head work, bore size, and fuel system.

Chicks dig a big stroker.

Plenty of links to stroker info on the bottom of this page:

4.7L stroker page.

Be sure to search the information at the stroker group listed... Almost any question ya could ask has answered. I took several days to read thru it & had most of my questions answered before I got started on mine.

Parts list & basic info on my 4.7L is on that page too. (Still under construction... the page & the motor!)


:anon:

Here's my stroker webpage:

http://www.jeep4.0performance.4mg.com/stroker.html

I'm still in the planning stage for my stroker but this is the recipe that I've decided upon:

4.6L stroker consisting of:
Jeep 4.0 block; 0.030" overbore and 0.010" milled from deck
Jeep 4.2 crank ('86-'90 lightweight version)
Reconditioned 4.0 rods
Custom forged pistons with 26cc dish and 1.37" pin height
Existing ported/milled #7120 head
9.5:1 compression ratio
Crane 260/272 degree cam
Mopar Performance 0.043" head gasket
0.043" quench height
Existing Ford 24lb injectors
Existing MAP adjuster
'99 and later intake manifold

Output should be at least 260hp/325lbft with this combination. I'm not in a hurry to do it so I can take my time, shop around for parts, and build it slowly.

Marc said:

I am getting ready to pull the motor out of my 89' Laredo and am looking at adding some umph to it. To up my current 4.0L to 4.7L or 4.2L, what is involved.

For 4.2L I know I need a 4.2L camshaft. What would I need to do to the head, cylinders and such. What about for 4.7L.

Click to expand...

You can't really go from 4.0L to 4.2L. The 4.2L has a smaller bore than the 4.0L. (Okay, you could sleeve the bores, but why bother?)

The "stroker" engines use a 4.0L block with the longer throw crankshaft from the 4.2L engine. That leaves you a choice of using the slightly weaker 4.2L connecting rods with stock 4.0L (oversized) pistons -- which results in an increased compression ratio and probably "ping" -- or you can use 4.0L rods with custom pistons.

Depending on how much you want/need to bore your 4.0L block, you can make a stroker come out to 4.5L, 4.6L or 4.7L. Some 4.0L heads are marginally better than others, but for simplicity use the one that belongs in your year XJ and do some light porting and polishing.

Yup, for a variety of combinations for parts, ya gotta check out Dino's page... Dino helped me make a few critical choices along the way & I made darn sure to list his page in my links.

A big 'thank you!' to Dino for gathering up so much usefull info on strokers!

:anon: ( :arrowl: I really dress like this.)