4.0 stroker

[geitin]

I need a rebould/stroker kit for a 4.0 90´xj do you recomend some kit??

 

[ForsterIV]

http://www.angelfire.com/my/fan/stroker.html

 

[Eagle]

The most reliable kit for a stroker was the one offered by Accurate Power. Unfortunately, very recently Accurate Power ceased operation with no explanation. We don't know if this is a temporary situation or permanent.

Get in touch with Dr. Dyno on this forum, and find the link to his personal web site. He has a tremendous amount of information regarding the stroker engines, and several sample "recipes" for building one without encountering the problems that some people run into.

 

[INI SLDR]

www.cliffordperformance.com/mance
Phone 1-951-303-2333

http://www.hescosc.com/
(205) 251-1472

I bought parts for my stroker ( 4.6 ) from both.

Here's the bare bones stroker

258 CRANKSHAFT/CONNECTING RODS

( dropped 11 pounds sometime in the 80's, makes a difference if you have manual or auto. Get the heavier one for manual/ less prone to stalling, the lighter one will spool up faster though)

high flow injectors OR high pressure fuel regulator
You don't need both

stock height pistons

Thats it!

I added a cam and bored .03 over stock, 60mm TB, header etc...

A TRUE stroker is made by using the 258 crank and your stock connecting rods. The reason these kits are so expensive is that they utilize special pistons with a different ( $800.00! ) pin height. The reason you use the 258 rods in the low buck version is to keep the pistons from making contact with your valves/head. The high dollar versions just lower the piston on the rod.

Call around to different machine shops, I got my crank/rods for free in exchange for my stock ones and just had to pay to have it turned.

 

[INI SLDR]

I almost forgot, its been a while since I did the motor but you have to cut the 258 crank down to match the 4.0 length. If not you will not be able to press the balancer on all the way to the timing chain cover. Its not much, maybe a quarter of an inch. Just compare the two and take off the difference. Good luck!

 

[Eagle]

www.cliffordperformance.com/mance
Phone 1-951-303-2333

http://www.hescosc.com/
(205) 251-1472

I bought parts for my stroker ( 4.6 ) from both.

I cannot recommend that someone in Iceland purchase from Clifford. Clifford was a great company, many years ago when Jack Clifford was alive and running the business. Jack is now deceased, and the company's reputation has (IMHO) gone down the toilet.

 

[Eagle]

I almost forgot, its been a while since I did the motor but you have to cut the 258 crank down to match the 4.0 length. If not you will not be able to press the balancer on all the way to the timing chain cover. Its not much, maybe a quarter of an inch. Just compare the two and take off the difference. Good luck!

That is only true if the 258 (4.2L) crankshaft came from an early 258 that had conventional vee belts. If it came from a vehicle with a serpentine belt there is no modification necessary.

 

[Dr. Dyno]

Get in touch with Dr. Dyno on this forum, and find the link to his personal web site. He has a tremendous amount of information regarding the stroker engines, and several sample "recipes" for building one without encountering the problems that some people run into.

Thanks Eagle. :cheers:
ForsterIV has already posted the link to my stroker build-up where there's a comprehensive parts list and a guide on which parts to select.
If you want to take a look at my sample stroker recipes, go to http://www.jeep4.0performance.4mg.com/stroker.html

 

[Lawn Cher']

That is only true if the 258 (4.2L) crankshaft came from an early 258 that had conventional vee belts. If it came from a vehicle with a serpentine belt there is no modification necessary.

What 258-equipped vehicles had serpentine belts? I have a 258 from a '87 YJ (yes, that one)and it had V-belts... did they change it between then and '91 when the YJ got the 4.0 liter?

 

[old_man]

I did a roll your own stroker and love it. It is by far the best mod I have done. I've got a couple of years on the motor and it runs fine. There isn't any shortage of info on parts and paying someone to put them all in one box seems excessive to me.

 

[Jeep 250]

What year of Jeep do you get an 258 crankshaft out of? Is this a 91 or newer Jeep? I have an 88 cherokee 4.0L with 102,000 miles on it. I have an used 92 HO Head that eventuly will put on when I get a 99/02 intake manifold.

 

[Jeep 250]

Ok I found it my self: http://www.angelfire.com/my/fan/selection.html
Crankshaft

At the heart of any stroker kit is the AMC 258 crankshaft (except for the JRE offset-ground 3.980" & 4.060" stroker cranks). This appeared in AMC 258 (Jeep 4.2) engines in various guises as shown below:

Year.........Casting No......Description
1971.........3199738.........For Borg Warner automatic
1972-80...3214723.........12 counterweights, 66lb, 64mm nose
1981-86...3235477.........4 counterweights, 46lb, 64mm nose
1987-90...3727...............4 counterweights, 46lb, 54mm nose

For comparison, the 4.0 crankshaft has 8 counterweights, weighs 55lb, and has a 54mm nose.
The #3214723 crank is reputed to the the strongest. The extra counterweights dampen vibration-inducing harmonics to produce a smoother running engine. The #3214723 and #3235477 cranks have a longer nose that was originally designed to accomodate a V-belt crank pulley. This needs to be shortened by 1.0cm if the serpentine pulley from the 4.0 is to be used. Alternatively, a custom 1.0cm thick spacer can be made to fit in front of the pulley thereby avoiding the need to shorten the crank nose. The nose of the #3727 crank is already the same length as that of the stock 4.0 crank so it doesn't require any modification.

 

[Dr. Dyno]

I guess someone found my stroker site useful.

 

[Jeep 250]

www.cliffordperformance.com/mance
Phone 1-951-303-2333

http://www.hescosc.com/
(205) 251-1472

I bought parts for my stroker ( 4.6 ) from both.

Here's the bare bones stroker

258 CRANKSHAFT/CONNECTING RODS

( dropped 11 pounds sometime in the 80's, makes a difference if you have manual or auto. Get the heavier one for manual/ less prone to stalling, the lighter one will spool up faster though)

high flow injectors OR high pressure fuel regulator
You don't need both

stock height pistons

Thats it!

I added a cam and bored .03 over stock, 60mm TB, header etc...

A TRUE stroker is made by using the 258 crank and your stock connecting rods. The reason these kits are so expensive is that they utilize special pistons with a different ( $800.00! ) pin height. The reason you use the 258 rods in the low buck version is to keep the pistons from making contact with your valves/head. The high dollar versions just lower the piston on the rod.

Call around to different machine shops, I got my crank/rods for free in exchange for my stock ones and just had to pay to have it turned.

Getting through the fog. Let me get this streight all I need is a 258 crank with 258 connecting rods, and use my 4.0L pistons?

 

[Eagle]

Getting through the fog. Let me get this streight all I need is a 258 crank with 258 connecting rods, and use my 4.0L pistons?

In short ... yes. But the minor dimensional differences between the 4.0L and 4.2L blocks will mean that you end up with a higher than stock compression ratio. Ping is a potential problem, so you should research the options regarding how to control that (short of running racing gasoline, of course).