New 4.2L mini-stroker recipes

[Cheromaniac]

Just added these to my stroker page. What do you think?

If you all thought that the old AMC 232 I6 crankshafts were only destined for scrapheap oblivion, think again. There are plenty of them around and with a 3.500" stroke, you can use them to convert a stock 4.0L engine into a 4.2L mini-stroker. While it doesn't have the displacement of an AMC 258 crank-based stroker, the 258 cranks are becoming increasingly scarce and expensive so a mini-stroker offers a low cost alternative to more HP/TQ:

4.2L Milder mini-stroker

AMC 232 3.500" stroke crank
Jeep 4.0L 6.125" rods
Silvolite UEM-2229 +0.060" bore pistons
Increase piston dish volume to 15cc
9.6:1 CR
CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.040" quench height
Ford 24lb/hr injectors with adjustable FPR or MAP adjuster for '87-'95 engines, Ford 24lb/hr injectors for '96-'04 engines, '99-'00 Chevy LS1 26.2lb/hr injectors for '05-'06 engines
262hp @ 5200rpm, 302lbft @ 3750rpm

4.2L Wilder mini-stroker

AMC 232 3.500" stroke crank
Jeep 4.0L 6.125" rods
Silvolite UEM-2229 +0.060" bore pistons
10.1:1 CR
CompCams #68-235-4 210/218 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.040" quench height
Ford 24lb/hr injectors with adjustable FPR or MAP adjuster for '87-'95 engines, Ford 24lb/hr injectors for '96-'04 engines, '99-'00 Chevy LS1 26.2lb/hr injectors for '05-'06 engines
270hp @ 5300rpm, 306lbft @ 4000rpm

[crusher242]

Too cool Dino. Maybe I'll use this one of these days for my one day 2wd slammed Eliminator project.

[GoMopar440]

Nice to know there are a few more parts sources out there besides just the 258's. And thank's again for helping the Jeep stroker community. More options = more strokers.

Out of curiosity, does the shorter stroke allow for more piston options than with the 258 cranks? I noticed you spec'd 4.0 rods on both of those recipies rather than the 232 rods.

FWIW: There's a bunch of those 12 & 4CW long snout 258 cranks available all around here, but the the 258 short snouts and the 232's are pretty rare. Maybe it has to do with the altitude I'm at (5000')?

[Cheromaniac]

Out of curiosity, does the shorter stroke allow for more piston options than with the 258 cranks? I noticed you spec'd 4.0 rods on both of those recipies rather than the 232 rods.

The Silvolite 2229 pistons (1.581" compression height) are the only ones that'll work with the 4.0 rods and 232 crank in a mini-stroker. I wouldn't even bother trying to find pistons that work with the 258 rods.
The only 232 cranks worth using carry casting no. 3214722 ('72-'79, 8 counterweights).

I decided that my milder mini-stroker was too close to the wilder one so I've revamped it into a configuration that'll run on 87 octane fuel. The 0.416" lift of the 68-115-4 camshaft also allows you to reuse the stock valve springs so it'll also be cheaper to build. The only differences from the 4.6 rockcrawler are the 232 crank, 4.0 rods, smaller piston dish volume, and lower quench.

4.2L Milder mini-stroker

AMC 232 3.500" stroke crank
Jeep 4.0L 6.125" rods
Silvolite UEM-2229 +0.060" bore pistons
Increase piston dish volume to 23cc
8.8:1 CR
CompCams 68-115-4 192/200 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.040" quench height
Ford 24lb/hr injectors for '87-'95 engines, Accel 24lb/hr injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
241hp @ 5000rpm, 294lbft @ 3000rpm

[amcinstaller]

232 cranks will likely become scarce too soon cause 232 went by the wayside long before the 258, at least in amc cars. but neat while it lasts for sure.

[4.0 Rambler]

Keep in mind also the early 232 cranks rear flange will need machining for automatic applications and an adapter.

[Dezertxj88]

This is the route I'm taking actually!
Its pointless for me to pay 150 roughly to deck the block when I can throw the 232 in it and gain displacment and lower cost of the build!

Original plan was 242 crank, 4.0 rods, .060 over silverlites to unshroud valves, dished to 17cc's, 0 deck to .005, quench being .053.
New plan is 232 crank, 4.0 rods, .060 over silerlites to unshroud valves, 21cc dish, piston will be .005 above deck, so -.005 deck height. All on the stock 87-95 single pattern cam.Motor is seeing boost, thats why the dish to drop the comp ratio.

Old plan was 249CI, 4.09L 9.11:1 compression ratio, .048 quench.
New plan is 255CI, 4.19L 9.12:1 compression ratio, .038 quench..this thing will be amazing on boost, either owuld of really, this option will be better, and be cheaper to build!

The reason I'm doing the 232 crank, is yes theres a slight advantage, obviously! But also because machining cost will be cheaper! I just payed 158 for the crank with .20 under mains/rods, comes with bearings. 158 with bearings, and 40 some dollars to ship it. So for under 200 bills it'll be shipping to my house. No deck height machining needed!
Before I was going to turn my crank .10 under and deck the block..that was close to 300 in machine work and still would need to buy bearings!! So if your looking at a stock rebuild like I was, then the 232 crank is the real winner! IDK why AMC/Chys never did it from the factory, they would of had 1 hell of an engine!

Idk all the specs on the 232 yet, but from what I've been told, no machining is needed with a 5speed? And the snout is the same at the 242.

Note: I specificually ordered the 4wt version..we will see what I get..the 4wt version should be lighter then the 4.0 crank..idk by how much though. ANyone have good specs on the 232 crank?
Weight, snout length?

[Cheromaniac]

Keep in mind also the early 232 cranks rear flange will need machining for automatic applications and an adapter.

That's why I said

The only 232 cranks worth using carry casting no. 3214722 ('72-'79, 8 counterweights).

ANyone have good specs on the 232 crank?
Weight, snout length?

If it's the '72-'79 crank, I believe it has 8 counterweights (two on each of the no. 1, 3, 4, 6 rod journals) like the 4.0 crank so it'll be similar in weight (55lb). It'll probably have the same snout length as the 258 crank of the same vintage (64mm).
The 4.0 rod/Silvolite 2229 piston is the only off-the-shelf parts combination that'll work with the 232 crank in a 4.0 block for a mini-stroker. If you already have a complete 4.0L short block you'd only need to buy the 232 crank, Silvolite 2229 pistons, new ARP 112-6001 rod bolts, main/rod/cam bearings, and new oil pump to rebuild the bottom end. Cheap and easy.

[IH 392]

I've often wondered why Jeep/Chrysler made a new crank for the 4.0's when they already had the 232 crank that was just/almost the same thing?

[casual]

Hey everybody, Is oleshot still around..I think it was him that used to dish pistons. My 2229's will be here on the 6th, and I need them dished to around 20-21cc's.
Are these safe to dish that deep?

Still waiting on my 232 crank to arrive!

[amcinstaller]

first paragraph:

http://www.jeepstrokers.com/forum/viewt ... =34&t=3001

[Cheromaniac]

I've often wondered why Jeep/Chrysler made a new crank for the 4.0's when they already had the 232 crank that was just/almost the same thing?

I've often wondered that myself. They could have easily used the 232 crank in the 4.0 block and with the stock 3.875" bore, displacement would have been 4058cc (~100cc more than with the 4.0 crank). They could even have kept the stock 4.0 pistons/rods (shared with the 2.5 I4) and just added a mere 0.025" to the deck height of the block to leave zero deck clearance. Compression ratio would have been 9.4:1 with the stock 0.051" head gasket.

[casual]

Double post.

[casual]

Incase anyones wondering, theres 3 different vendors on ebay selling the 72-79 cast cranks for around 150 shipped to your door.

[Dezertxj88]

Dino is there any concerns for PVC? The pistons will be above deck by .005 give or take a little..and with a .043 headgasket that gives a .038 quench. I was curious if I could get that quench down to .025 without worrying about PVC..
I'll be running the OEM 87-95 cam, 2.00 intake valves, 1.50 exhaust..I'm hoping maybe you know the limit, or maybe someone knows the limit?

What I was hoping to try was,

.060 over
232 crank
59.2cc (getting final numbers, may be slightly bigger)
-.018 deck clearence
.043 head gasket
19cc piston dish
6.123
75 IVCA (stock 91' cam)
2.00 intake/1.500 exhaust (LS1 valves)


That'll give me 9.32 SCR & a .025 quench. Only worry is will there be any PVC? The tighter quench will bump me up from 9.1 to 9.3 but I'm not to worried about it..still should run on 87 octane since its got such a tight quench. I want to get my quench as low as possible!
I know con rod stretch and piston rock are a concern..I just don't know how much..I can't imagine our rods stretching very much with a 5300rpm limit..