Building a stroker

[cjsxj87]

I know its been covered many times. I know research, i am but I need facts and links.

I want to build a "cheap" stroker. I have a 4.0 from my old 95 that will be used. Waht do I need for a 4.5 stroker? Should I just get the block bored and do a 4.6? I know I need a 4.2 crank and rods, what else do I need? What Cam should i go with? Cam kit?? ANY INFO and links. This is my first engine build/working on the internals.

 

[Dr. Dyno]

You'll find all the info. you need and some on my sites:

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

You'll definitely want to get the cylinders rebored so that they're round and true, otherwise you won't get good ring seal. Therefore you could overbore +0.030" and build a 4.6.

 

[1990JEEPXJ]

My 4.X liter Jeep Stroker Recipe
By Corey Kruchkowski
Note 1: All part numbers current as of May 2009.
Note 2: Where not mentioned, standard engine rebuilding
techniques apply.
Note 3: This is a tested recipe. Fieldtested,
and comp tested.
The
Block:
‐ To avoid unnecessary frustration, run the block from the
generation of engine that came in the vehicle that you are
placing the motor into. There were 4 versions/generations of
the 4.0L block and all had minor EXTERNAL variations. Read
the casting under the exhaust headers.
‐ If you are running a competition buggy, run a highmileage
Renix 4.0L engine (casting dates up to 1990, Gen 1 cast on
drivers side). It has higher nickel content and will be well
seasoned. It is the toughest block from a metallurgical
standpoint, and highly recommended for competition.
‐ Bore 0.040 over if possible. The engine will run cooler, and
one more rebuild (0.060) will remain if the unforeseen
occurs.
‐ Have new cam bearings installed.
‐ Install bottomend
studs in the block. Hesco part number
HESMS6 Hesco ARP Bottom End Studs. Install as per
Hesco/ARP instructions.
‐ Install head studs in the block. Hesco part number HESHS6
Hesco ARP Top End Studs. Install as per Hesco/ARP
instructions.
The Crank:
‐ The best 258 (4.2L) crank to run is the 198790,
3727 4
counterweight crank. It weighs 46lbs, and has a 54mm snout.
This crank is a direct bolt in to the 4.0L block and works with
a stock 4.0L harmonic dampener.
‐ If 3727 cranks are unavailable or difficult to find, the second
best 258 (4.2L) crank to run is the 198186,
3235477 4
counterweight crank. It weighs 46lbs, but has a 64mm snout.
This crank needs a 10mm spacer or 10mm removed from the
snout to work with a stock 4.0L harmonic dampener.
‐ Under no circumstances should a 12counterweight
crank be
used to build a Jeep inline Stroker engine.
‐ Have the crank spinbalanced.
Generally this only takes a
competent shop 1/2hr – 1hr, as they are very close from the
factory. Have all the oil holes chamfered. Check the pilotbearing
journal if you are running a standard trans,
machine/enlarge as necessary.
The Rods:
‐ You must run the longer 4.0L rods. This is both a power and
longevity issue. Yes – it requires custom pistons.
‐ Deburr all the casting flashes off the sides of the 4.0L rods.
Blastpeen
the rods in a highpower
bead blast cabinet to
surface harden. Resize. Install ARP stud kit PN 1126001.
Install as per ARP instructions.
‐ The casting number for all the years of the 4.0L rod is
53020126.
‐ Weight balance the rods before pressing them into the
pistons, then weight balance each rod and piston assembly
endforend.
The Pistons:
‐ Now that Keith Black has added 4.x liter Stroker pistons to its
catalog, these are the ONLY pistons to run in a normally
aspirated 4.x liter Stroker engine. Installing these pistons on
a 4.0L rod will result in a deck clearance of 0.028, on a block
that has not been decked. Two varieties have been created.
‐ KB Silvolite forged 944 come with a 21.7cc dish, resulting in a
9.5:1 compression ratio. This is the piston recommended for
stock 4.0L fuel systems (minus larger injectors of course) and
the milder 4.0L camshafts.
‐ KB Silvolite forged 945 come with an 11.4cc dish, resulting in
a 10.5:1 compression ratio. This is the piston recommended
for modified 4.0L fuel systems, and the most aggressive cam
profiles.
‐ A little known fact is that Chevy 283 rings work in Jeep 4.0L
engines. Run PlasmaMoly
racing rings for easy breakin
and
toughness. I like Hastings products, the quality is control is
excellent: PN 2M5506(
0.20304060).
File to fit for a
perfect match.
The Head:
‐ If the correct head is chosen, no modification is necessary to
the intake and exhaust runners.
‐ There are 4 head castings for the 4.0L head.
‐ The HO, or HiPo heads were in existence between 1991 and
1998. Casting numbers 7120 and 0630. The 7120 heads have
the coolant gauge sender necessary for ODB1 systems. These
two castings are the only ones worth considering for an
engine build.
‐ A 5angle
valve job is necessary.
‐ Stock valves may be reused
in all but the most extreme
applications.
‐ To run the camshafts I recommend, use MOPAR PN 5249464
springs with MOPAR 4452032 retainers. This combo is good
for cams with over 0.0500” of lift.
The Camshaft:
‐ I only recommend three cams for the 4.0L Stroker. Crane is
no longer in business, and one company in particular
continues to provide the best cams for this engine. I have
tried Isky, Clifford, Hesco and others – but came back to
Comp. Still the best profiles for this engine.
‐ For each cam, use Comp antipump
up lifters. PN 82212
‐ Stock replacement 4.0L pushrods are acceptable in normally
aspirated applications.
‐ For the best bottommid
trail crawling/tractor engine, use
Comp Cams PN 682324.
‐ For a midupper
screamer competition engine, use Comp
Cams PN 682394.
This cam will work best with compression
ratios of 9.5:1 and higher.
‐ For a great allaround
engine with mild street manners,
choose Comp Cams PN 682314.
Extras:
‐ Choose a double roller chain for durability, and reliability
during competition/racing and decreased friction. These
chains are manufactured and sold by Cloyes PN 93127,
and
supplied by MOPAR P5249519, and Comp Cams COC3127.
The chains work in all the 4.0L engines – a minor DIY
modification is required to the way the cam shaft is retained
in 99 and newer blocks (it is quite obvious once assembly is
undertaken).
‐ Run Harland Sharp pedestal mount rollerrockers
– they bolt
in with no modifications required. You must always check for
head & valve cover clearance and proper lifter preload. PN
S40196
FINAL WORDS:
• The above combo is the best balance of power and budget in
my opinion, when building a Jeep Stroker motor.
• If done properly, and attention to detail is maintained
throughout machining and assembly, 300+ horsepower and
350+ ft/lbs torque is expected with the 9.5:1 pistons. I am
unsure on the numbers for the 10.5:1 pistons (more) – but
fuel upgrades above and beyond oversized injectors must be
performed. Contact me for details on your specific
applications.
• Please let me know what you think, I welcome your input. If
you use this combo to compete – please give me credit for
your engine specs.
Best Regards,
Corey Kruchkowski
[email protected]
mobile (780) 9334012
http://tntgp.com

i know its long but LOTS of good info. this guy knows his stuff

 

[alex22]

When I took apart the engine I'm using for my stroker engine the bores still had the factory cross hatch, almost no wear ridge at the top of the bore and the bores were round within .0015. If I wanted to be extra cheap I could have just ball honed the cylinders and used stock pistons and new rings and it would probably have run fine. Now I'm not saying that 4.0 blocks don't wear out and that you should use stock size pistons, just that if you want to spend as little as possible have the bores measured by a machine shop to check for wear.

I'm not sure why the 12CW crankshaft would be undesirable in any stroker. For an automatic they would not be the best way to go, but the rotating mass would be helpful with a standard transmission (I forgot if you have an automatic or not). SCAT is now producing a stroker crankshaft that is built with some of the 4.0 specs; it has 6 counterweights about the same as the 4.0 crank (54lbs IIRC) but has the stroke of a 4.2.
I haven't heard about the Chevy 283 piston rings yet, neat trick.

Decking the block to get as close to a zero deck as possible will keep the quench as tight as possible which will result in a better burn in the combustion chamber.

When it comes to the pistons you will have to weigh the cost of a set of KB pistons vs. a set of 4.2 rods and cheaper cast pistons. It all depends on what kind of deal you get on parts.

A quick port and polish on the head and a good valve job will give you some good power gains as well. Chevy LS-1 valves can be used as oversized valves. If you have any experience porting it can also be a cheap way to make more power. If you don't know what you're doing in the port you can do some real damage.

Since you're on a budget the stock rocker arms will do just fine for you, just replace any that are worn out. Here is some good info about rocker arms.

Check out www.jeepstrokers.com out for some more info.

One more thing to keep in mind is that if you build the cheapest stroker possible then you're the owner of the cheapest stroker that you could build. If the engine in your jeep is still running strong you should think about waiting a few months to save up more money so you can have a better engine.

Where do you plan on having the machine work done?

 

[biztyke]

i know its long but LOTS of good info. this guy knows his stuff

yeah, he sounds like he knows his stuff. but it also sounds a little narrow minded. i have seen and heard of many people who run the 12 counterweight crank with no problems, in fact many prefer it over the 4 counterweight for crawling. i also see no problem running the shorter 258 rods, again many out there have done it with no problems. i think any added wear by using shorter rods is going to be negligible, plus you save a good chunk of change by not having to run the KB pistons($450 vs $100-120).

i also highly doubt he got over 300HP like he claims.

then again, i am no expert(yet)......just going by what i have read from many who have done it before.


i would check out jeepstrokers.com, tons of valuable info to be had. i have been doing stroker research for a while now and am planning on a build soon(as soon as money allows me to).

dino's sites are a good place to start, here are a couple others:
http://www.rockcrawler.com/techreports/stroker40/index.asp
http://www.fourwheeler.com/techarticles/engine/129_0711_1987_2006_jeep_40l_inline_six/index.html

really though, you are not gonna find a single site with absolutely everything laid out nice and neat for you. just keep reading through all the sites listed here, keep searching and you'll start to understand it all. definitely try and understand the math behind it, there is a calculator at jeepstrokers that is handy for that. compression ratio and quench will determine what kind of fuel you can run without ping, and both depend on some variables you'll have to work with.

my thinking is that with something like an engine build it is best to take the time to thoroughly understand everything before you just go ahead and slap something together.

 

[Talyn]

yeah, he sounds like he knows his stuff. but it also sounds a little narrow minded.

He "sounds" like it but he doesn't. That recipe he has there may be fine, some stuff is completely unnecessary and some poor info, but its fine. But as a whole, he doesn't.

 

[Dr. Dyno]

I agree with everything Corey said except for

Under no circumstances should a 12 counterweight crank be used to build a Jeep inline Stroker engine.

I wonder if he said that because the 12 cwt crank is 20lb heavier than the others. I have it and I like it 'cause the extra counterweights dampen harmonics and my engine revs smoothly to 5000+rpm. Almost 6 years and 60k miles on my stroker.
I also think his 300hp/350lbft quote is somewhat optimistic; 270/335 is more likely.

 

[Talyn]

There is no need to run Hesco ARP crank bolts and head studs, as is there is no need for a 5angle valve job. You also don't need roller rockers.The correct number for the Hastings Moly faced rings is 2M667

 

[old_man]

I've got almost 100k on my 4.7L stroker. I think it was the second stroker built in Colorado around 8-9 years ago. I am running the 12cw crank. It is superior when running a stick like I used to have. It will not rap as fast as a lighter crank. Other than that, it has worked flawlessly on my automatic.

 

[clean4drxj]

Caleb.. there was a local place in colcheter CT that builds strokers for not alot of money providing you supply the parts. Basically just go with with 258 crank and rods (redone) ARP fasteners, good set of pistons and becareful on what cam you use as alot of people have had various problems do to todays oil and the manufacturing of the cam, maybe stick with mopar stage 1 or 2, the rest is self explanitory and in the links above.

 

[wy_jeep]

I've got almost 100k on my 4.7L stroker. I think it was the second stroker built in Colorado around 8-9 years ago. I am running the 12cw crank. It is superior when running a stick like I used to have. It will not rap as fast as a lighter crank. Other than that, it has worked flawlessly on my automatic.

I don't know about superior...you make it sound like running a 4cw crank with a 5spd is inferior. I have the 4cw crank with a 5spd and it drives just fine. I wouldn't choose a 4cw over a 12cw, or vice versa. I would get whichever one is first available.

Anyway, to the OP. I would recommend getting the block bored. Around here it's roughly $10/cylinder to bore/hone, why not? 4.2 crank and rods are the only stroker specific parts you'll need. Everything else will be the 4.0L parts (water pump, oil pump, gaskets, etc). Maybe do a search on the camshafts people are running. I know a popular choice is the Comp 68-232-4. I decided to run the stock cam. Depending on the cam you get, you might want to upgrade the valvetrain.

The links Dr Dyno provided were by far the most helpful to me when I was building my engine. Good luck!