New 4.2L mini-stroker recipes

Newbies, and basic Stroker Recipes... Get started with your first stroker here!!
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

Dezertxj88 wrote: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 wouldn't run the quench that tight; 0.030" would be the absolute minimum but why chance it? With larger 2.0" intake valves you're really going to test the PVC but you definitely don't want the pistons to hit the head at TDC.
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Re: New 4.2L mini-stroker recipes

Post by Dezertxj88 »

Ya I think I'll stick with .038 quench and I'll clay the motor at that point as well..I know I'll get the head planed to get it straight and clean, but only the very very minimal amount! Its not worth the risk to try and go further now that I've slept on it for a night.
More reading online and such last night just confirms, steel rods will stretch around .03 or so and aluminum slightly more, but I couldn't figure out how to calculate a ball park figure for us! I know most LS guys were telling me steel rods stretch .02-.03 around 6800-7000rpm. So I don't think ours will stretch that much, but they will stretch still..
And just to say if they stretch .02 around 5000rpm, then I've got .018 for clearence which is very very close lol. I'll be claying my motor, stock cam, 2.00" intake valve and .038 quench and go from there.

I really wanted to run a bigger cam, but we will see..I don't want to do it, but if nessesary then I'll run the stock .051" head gasket to gain a little clearence, but thats a last resort!
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Re: New 4.2L mini-stroker recipes

Post by Dezertxj88 »

Hey Dino I was curious about pistons..why are the 2229's the only option for a 4.2L? Is it the compression height of 1.581"? Can a lower or slightly taller compression height be used?
My block is at the shop and I figured what they hey, only live once right? I'm going to have them sonic check the walls and see if it's got enough meet for a 4" pistons..its a 1988 block, well seasoned, so if its got the thickness it should be ok..175" is minimum right?
I was looking at the SBC UEM-S3456HC- 4.00" bore, 1.588 compression height..Its dished, with valve reliefs, but I'm sure I can get it dished out further if need to adjust compression accordingly, the only thing I see as a concern/problem is the .927" pin diameter because sock pin diameter is slightly bigger.
http://www.summitracing.com/parts/UEM-S3456HC-STD/

Using these pistons would put them .012 above the deck, a .051 head gasket can be used to avoid any PVC. Doing so gives you a .039 quench. Using a 3.935" 2229 piston and a .043 head gasket, I get a .038 quench..so not much changes except a bigger bore.

Also what about using a lower piston compression height? I'm shooting for mid 9's for compression, so high compression isn't my desire!
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Re: New 4.2L mini-stroker recipes

Post by Cheromaniac »

Dezertxj88 wrote:Hey Dino I was curious about pistons..why are the 2229's the only option for a 4.2L? Is it the compression height of 1.581"?
Other 4.0 pistons are too tall except for the Sealed Power Z677AP's which have a compression height of 1.585", though you could use the Sealed Power Z525AP's for the Jeep 2.5 I4 engine that have a compression height of 1.580".

http://www.summitracing.com/search/?key ... 77AP&dds=1
http://www.summitracing.com/search/?key ... 25AP&dds=1

My advice would be to go +0.060" and call it a day.
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Re: New 4.2L mini-stroker recipes

Post by Dezertxj88 »

Ya it just seems alot easier. Good news is my block will hold a 4" piston :banana: Mic'ed out at .181-.183 with a 4" over bore..and I think thats enough?

Bad news is, since my crank still hasn't arrived, pistons and valve train have though, but I'll be stopping my stroker project! I've been looking for a cost effective diesel swap ever since I saw a RHD 2.5L for sale in my area about a year ago..ya saw one in California last year, and guy had a whole spare drivetrain, wanted 3k but couldn't keep the jeep running so I passed it up. I ran into a guy on pirate4x4 who swapped in a OM606 but he extended the front end like 4-6" which I didn't want to do..so after searching the last few days I found the OM617 that a guy did in a MJ, Xj and some wranglers..and knowing I just swapped in 3.55's with my ax15 5speed and 30x9.5's, it should be perfect with getting me in the powerband of the 617. I'm around 3" of lift, but will probably go up to 4" for more clearence for the oil pan if needed..My axles also streched 2" forward so that may or may not help.
I actually sold my spare motor last night, kind of sucked :| but theres quiet a few om617's merc's around me for $900-2000. So I'm going for the swap, it was pointless for me to do a more efficient jeep 4.0 build to gain mileage when swapping the diesel will get way better mileage and similar power numbers. I figure gas will be $5 a gallon here shortly, its like $4.52 now :frustrated:, so nows the perfect time for a diesel..diesel being $4.38 currently, but bio diesel, veg, atf, oil...all helping the planet and all cheap to run. And the diesel fits my ExPo/Military theme better:)

Sucks cause I really wanted to be one of the first with a 4.2L mini stroker. I wanted to document everything for people to come, and really wanted to see how efficient the 4.0 can really be made with a super tight quench and maybe around 9.1-9.6:1 compression.
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Re: New 4.2L mini-stroker recipes

Post by JeepSpeed18 »

So If I am reading correctly. I'm going to have to modify my 232 crank to work in my stroker build becuase I have an automatic?
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Re: New 4.2L mini-stroker recipes

Post by IH 392 »

IF your 232 crank is a '72 or later it shouldn't need modification.
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Re: New 4.2L mini-stroker recipes

Post by JeepSpeed18 »

Ok Thank you! :cheers:
_=====ooooo
//__l_l_,\____\,_____
l_/-\_l__l_/-\_|lllllll|
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_(o)_)___(o)_)--o-)_)

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Re: New 4.2L mini-stroker recipes

Post by Jeepinscott »

Dezertxj88 wrote: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..


I built one of these mini-strokers and took it to the extreme with zero piston dish. I had to run 100 octane fuel but made 275hp at the wheels through a manual, t-case, and ford 9" on 33" tires. There is a lot of room between the pistons and valves, it shouldn't be an issue. I used 1.6:1 Harland Sharp roller rockers and an agressive cam and still had room. It would hold 5800rpms for hours at a time.

I wouldn't run the 2.00 valves, the 1.94's flow better. 2.00's get into significant shrouding.
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Re: New 4.2L mini-stroker recipes

Post by Dezertxj88 »

Jeepinscott wrote:
Dezertxj88 wrote: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..


I built one of these mini-strokers and took it to the extreme with zero piston dish. I had to run 100 octane fuel but made 275hp at the wheels through a manual, t-case, and ford 9" on 33" tires. There is a lot of room between the pistons and valves, it shouldn't be an issue. I used 1.6:1 Harland Sharp roller rockers and an agressive cam and still had room. It would hold 5800rpms for hours at a time.

I wouldn't run the 2.00 valves, the 1.94's flow better. 2.00's get into significant shrouding.

I agree with the 2.00" intakes..not worth it..I've ported my head alot and opened up the chambers as much as I'm comfortable with..on a 0630. And I think the shroudning was worse that an unported head on stock valves :?
I'm going to get the intake valves turned down to 1.96 I believe.. Ls1's were only chosen because I got a complete valve train for around 40 bucks, its all stainless, all back cut & swirl polished & weighs less than stock:)
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Re: New 4.2L mini-stroker recipes

Post by Coffee Commando »

Dezertxj88 wrote: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?
Holy awesome. I'm about to rebuild another stroker when I go home in a few weeks. I'm glad I just registered with this site.

I bought an Avenger Supercharger back in January from someone. I'm going to use that so I'm definitely going to need lower CR than my current 9.6. I'm attempting to hold a very intricate raffle on Cherokee Forum in order to sell it.

I'm thinking I'll bore .030" over with my new engine and dish out the SV's to 23 CC as specified. That should put me at 8.9:1 CR. I'm only going to 6 lbs of boost with it.

I'm not sure where that red-line is on running 6lbs of boost vs. Compression Ratio but I would like my engine to last longer.

I'm also not sure what horsepower my crank is capable of. With my 4.6 and all the extra mods I should have been at 290-300 HP at the crank considering I have every bolt on modification in existence in addition. The only thing I don't have are the larger 2" intake valves and a ported head.

Well, I'm going read my pants off now that I've found this site.

Long live the ministroker. You rule Dino. You document and experiment with stroker builds like a mad scientist.

I'll be performing your 180 degree thermostat resistor modification when I build this new engine. I'm opting for a 5K Ohm resister since I'm utilizing a Supercharger with my stroker (aka Super Stroker).


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Re: New 4.2L mini-stroker recipes

Post by Coffee Commando »

Where can I find the 232 crankshafts at? There was nothing E-Bay and googling is yeilding nothing so far.

I also searched Car-Parts.com and it found no matches in the U.S. whatsoever.

I really want this crank. I like the idea of a lower compression engine still yeilding 241 HP and allowing me to supercharge it safely 8-)
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Re: New 4.2L mini-stroker recipes

Post by amcinstaller »

id start scowering junkyards for old amcs, and maybe make friends in some amc forums
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Re: New 4.2L mini-stroker recipes

Post by IH 392 »

Coffee Commando wrote:Where can I find the 232 crankshafts at?

Knowing where you're at will help us help you!, last time one of the guys was saying he couldn't find a 258 crank I asked him to specify his location and within 15 minuets I'd found him a whole engine on Craigs List! and for only $75!
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Re: New 4.2L mini-stroker recipes

Post by Coffee Commando »

Ocala Florida, 32134 zip code.

I assume that any engine by AMC that is a 232 between the years of 72 and 79 (I have an AW4) is compatible? Not just the CJ-5?
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