2012 Stroker build.

[Cjbeer]

Hey. i am new to this forum but not to the jeep world. i will get straight to the point. i am building my first motor hope for my 96 xj. i have been getting a lot of info off of this site and don't like having to go back so far in the forum to find things.

so far i have
94 block
93 7120 head
4.2 crank with the 4 weights 2 in snout. all at the machine shop getting cleaned and magna fluxed

my questions are what kind of cam and pistons and rods should i run? i want to get to the 4.6 mark. would like to run of 87 octane. plan on all new valve train so any thoughts on that would be great and will the 96 fuel injectors work? . this jeep will be used for mild off road/rockcrawl but mostly street and hwy driving to northern AZ so there are some nice hills to pull. also as i know with almost everything there are little issues that come along with building a motor or swap, anything to look out for?

[Retlaw01XJ]

0.030" overbore will get you 4.6 liters.
What's your budget?
With 4.2 rods, you could use stock replacement pistons but would have to have the dish machined larger to run 87 octane.
With 4.0 rods, you can step up to the forged K-B 944 pistons but you'll still have to have the block decked for the best CR match. ARP rod bolts are a nice addition, but you'll have to have the rods resized.... maybe $100 + $45 for the bolts.
Late stock cam is okay. Mild performance is a bit better. But a bigger cam will need additional $$ for better valve springs and possible head cutting for the springs.
There are some good valve/spring options out there, but you have to plan ahead!

[Cheromaniac]

I have two questions before I guide to what to do next:

1. What's your budget?
2. Do you really want to restrict yourself to 87 octane fuel? If the answer is yes, it looks like your only option is to build a stroker similar to my "rockcrawler" recipe.

[Cjbeer]

My budget i would like to stay under the 2500 range. as for 87 no i dont want to limit my self i would just like to run it on it if i can. i do have a daily driver its AN 02 DODGE 5.9 V8. Both not great on gas but thats what comes with lifted off road toys. back to the jeep i look at it as im building a motor i should build it right and reliable. good power and decent to the same 13mpg i get now.

Jeep mods
6 inch lift
285 75 16 bfg
dana 30 front with powertrac locker
rear cry 8 1\4 limited slip
4:56 gears
stock exhaust header with 2.5 Exhaust the rest of the way

[Cheromaniac]

How about this recipe?

4.6L low-buck stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith Black UEM-IC944-030 pistons
9.6:1 CR
CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mill block deck 0.020"
Mopar/Victor 0.043" head gasket
0.050" quench height
Ford 24lb/hr injectors with adjustable FPR or MAP adjuster for '87-'95 engines
264hp @ 4900rpm, 324lbft @ 3500rpm

[martin809]

Dino, with this set up do you need mopar performance springs and if you use them do you have to machine the seats. Or can you get away with using the springs with no machining.
My concern comes from seeing a few cam bering failures.
Thanks for your time.

[Retlaw01XJ]

There was one user that mentioned he had to machine the heads to use those springs. I don't know the details.
What are the specs for the Mopar springs?

Dino, what is your opinion on the Crower 44243 cam? It has less lift that appears to be compatible with the stock springs, yet still gives increased performance over the stock cam..

[martin809]

Here is the link to the springs
http://www.summitracing.com/parts/DCC-5249464/

[Cjbeer]

With this cam CompCams #68-231-4 206/214 degree camshaft can that be run with the stock valvetrain. Also I have a 96 engine do I need that map adjuster. Plus I have the 7120 cast head. You mentioned a port. Is that needed on the head?

[Antifreeze2]

With this cam CompCams #68-231-4 206/214 degree camshaft can that be run with the stock valvetrain.

Stock valve springs go to .430 lift, some have had success up to .450 lift. That cam is .462/.485, and they state it needs new valve springs.

[Cheromaniac]

There was one user that mentioned he had to machine the heads to use those springs.

Dino, what is your opinion on the Crower 44243 cam? It has less lift that appears to be compatible with the stock springs, yet still gives increased performance over the stock cam.

You DON'T need to machine the head to use the Mopar 5249464 springs. I used them when I first built my stroker.
I can see the appeal of using the Crower 44243 cam in a stroker and you could indeed reuse the stock valve springs. That cam will provide a lot of grunt at low rpm but will fall flat by about 4500rpm.

[Cjbeer]

Ok thanks. It seems like choosing the cam and what needs to be done to the head is going to be the hardest part. Can I count on the machine shop/ builder to figure out the head and valves if they have it all block,crank, rods, pistions, cam, and the head it self?

[Cjbeer]

Was at a Napa today and just asked if they sell pistons. They have a .30 over piston for the 4.0 are they a good product?

[Landon]

I think the consensus is that the stock pistons are too high with the 4.0 rods, and too low with the 4.2 rods. By the time you deck the block and dish the pistons, you could have higher quality pistons and a better rod to stroke ratio with the KB944. All that said, I am still looking for experiences with the stock pistons and no machining. Seems marginal on static compression ratio, not enough quench, and may need an aftermarket cam investment to get the dynamic compression ratio down. Run some numbers through the compression ratio calculator. Feed your head. It's healthy.

[herbiehind]

I think the consensus is that the stock pistons are too high with the 4.0 rods, and too low with the 4.2 rods. By the time you deck the block and dish the pistons, you could have higher quality pistons and a better rod to stroke ratio with the KB944. All that said, I am still looking for experiences with the stock pistons and no machining. Seems marginal on static compression ratio, not enough quench, and may need an aftermarket cam investment to get the dynamic compression ratio down. Run some numbers through the compression ratio calculator. Feed your head. It's healthy.

i thought the stockers ' greater pin height would be taller either way .
1. Deck height: This is the dimension from the crankshaft centerline to the head face of the block.
2.Crank throw: This is the radius the rod journal sweeps out as it rotates around the main journal centerline.
3. Crank stroke: This is twice the crank throw and represents the amount the crank moves the piston up and down the bore.
4. Rod center-to-center length: Usually referred to as the rod length
5. Piston compression height: Sometimes also called the pin height, this dimension refers to the distance between the center of the wrist pin and the top surface of the piston that makes a close approach to the cylinder head face.
6. Swept volume or Cubic Inch Displacement (CID): This refers to the amount of air the cylinder is capable of drawing in as the piston moves from the top of the stroke to the bottom.

Read more: http://www.popularhotrodding.com/tech/0 ... z1mU8TSndW