4.0 stroker questions

Lee

Lee

ECGS
Joined
Mar 20, 2005
Location
Louisburg NC
A little back story. Motor in my 96 xj has died at 275k, been knowing it had issues for awhile. Picked up a running 4.0 a few weeks back that is also a 96+ nvh motor. I originally planned to do a quick stock freshen up with bearings, rings, timing set, oil pump and send the head to the machine shop to have them go through it.
After tearing it down I think I have decided why not build a stroker? Started doing some research and now have a million questions. I have been thinking for ease and sake of time about ordering one of these two kits
http://www.cleggengine.com/jeep-4-0l-stage-1-stroker-kit-9-0-1c-r-4-5l-4-6l-4-7l-242-amc.html

Talked to these guys today, waiting on a full estimate with changing a few things and adding some parts. I would actually be getting 4.0 rods and dished pistons instead. Said I should actually end up with an 8.8:1 cr, no decking of the block. Would have to run one of their cam kits.

http://m.ebay.com/itm/140894789023?nav=SEARCH


Not sure what cr you end up with or if it requires decking the block. Need to call them tomorrow.

Anyways, long story short. Opinions on buying a kit vs buying individual pieces and building your own setup? I know there are a bazillion different recipes to build a stroker.
 
Mine is a 4.2 crank and rods with 4.0 pistons, and it's been running strong since 2003. But if I had it to do over again, I'd go 87-91 4.2 crank (which I have in mine) and whatever 4.0 rods were in my engine and the custom offset pistons that you can get these days. I'm still running stock cam, injectors, intake, head etc and I'm pretty happy with it. I'm sure all the performance stuff make a it better, but the difference between 4.0 to stroker is phenomenal even with everything else stock.
 
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I'm running an 89 258 crank and rods and 4.0 pistons. Pre 95 block. Ported head and the biggest Crane cam they said would work with factory fuel injection and map sensor. You Could run larger cam with a split second programmer for the map.
Running .060" or .100" shims under stock replacement valve springs to get the open pressure up some. It's been too long to remember. Stock valves with a good 3 angle job on them.

Built this in the fall of 05 and it has over 80k miles. Drove it daily till 08 when I swapped tons and still gets beat on now ( knock on wood).

Didn't really do anything special. I'd use the 89-90 crank so it has the proper snout for serpentine belt. Nvh blocks are better for higher nickel and better webbing, as well as the main stud girdle.

It's better to use 4.0 rods and custom raised pin pistons bc you get a better rod length to stroke ratio, but with stock rev limit, it's not really an issue. It can be done much much cheaper using stock replacement 4.0 pistons and 4.2 rods.

I didn't deck the block as the machine shop checked it for flatness and was within spec. My static compression was around 9.7:1, with polished chambers. I run 93, but have had to run 89 on occasion due to only thing available, and I didn't notice any pinging.

I run some type of orange top injector, not sure exactly what it came out of, I think zj 318, and disconnect fpr to get max (45) all the time.

Only thing I want that I don't have, is ability to adjust timing to get some more out of it. However I have beat the snot out of this motor and it has broken tons of parts behind it, so really no need for any more hp.

It has survived daily trips to the rev limiter and two trips to 265 deg while being stupid.

Make sure to use good assembly lube on the cam and order some good high zddp oil for the break in. Koup should know about some green oil from PA that is good for flat tapper cams.

I would piece together a "kit" and spend the money/time porting the head and getting a good set of bearings, and a melling high volume oil pump.

Also, make sure you get correct size 2.0" freeze plugs. Some are 1.997, some are 2.002 or something dumb like that, it will spit out the smaller ones at high rpm.

Plastigauge everything during assembly.

You may have to clearance block for rod bolt clearance at the base of the cylinder walls. I didn't, but I know some have. You should be able to just use some washers to space the main stud girdle down for clearance.
 
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Lee said:
Did you deck your block Matt?
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No, nothing was done to the block (other than using some lock washers to space the stud girdle. I believe they skimmed a couple thousandths off the head but its been over a decade so my memory is not 100% clear.
 
Keith Black makes dished pistons to work with the 4.0 rods. Without a decked block or shaved head it gives you right around 8.8:1 CR if I remember right. I will try to find the part number. With a stock or close-to-stock cam I think the setup would work great for a DD on pump gas. If you deck the block 0.020" and run the .043" head gasket the CR will be around 9.6:1. Whatever you decide, piece together the parts. That way you get exactly what you want. The OEM cam with a custom grind would be my recommendation. I have heard mixed results with aftermarket versions (different retainers, narrow lobes, etc.). Every stroker cam failure I've read about involved a cam from an aftermarket manufacturer.

Crower makes lifters designed to increase the oiling to the Camshaft in these engines. I think they are called Cam Savers. The oil pressure will drop a couple psi but I think its worth it if the cam will live.

@ScottR has a stroker in his tj. Not sure the specifics on the build. I think Newcomer Racing built it for him.

EDIT: The pistons are part number UEM-IC944
 
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Last one I did was for a 2000 WJ. CJ style crank, but used a spacer to line everything up belt wise. I used 4.2 crank, rods and 4.0 pistons as it was a budget build. I had the deck machined down 0.035" to get the quench where it needed to be. We did have to locate the correct length pushrods, but everything else was re-used.
Runs like a top and does not require high test as the quench is dead nuts in spec.
 
You talking about Brad Penn oil, Scott? I remember it being on the shelf at Napa, no one ever bought it haha. Some guys swore by it, other swore by Red Line. I used Red Line when I put the cam in my old truck, didn't have any problems. I probably could've used grinding compound in that thing and been alright. I remember a sales guy from Brad Penn coming into Senex, trying to sell us grease and oil, way too pricey for the amount we used.
 
My head is still spinning from all of the recipes. Buddy_holly, the kit from Cleggs is pretty much the formula you are taking about. They never emailed me my final estimate for all the parts I want. I think I am going to buy their basic kit at a minimum and fill in the rest of the parts else where. New scat crank with bearings and rods already sized and ready to go almost sounds to easy. Yes I realize I could probably scrounge and put the kit together cheaper. But my time is worth money and convince to me. Drop the block off for a dip, freeze plugs and a .030 overbore. Rework and port the head and put the thing together
 
well I bit the bullet and ordered this today http://www.cleggengine.com/jeep-4-0l-stage-3-stroker-kit-9-6-1c-r-4-5l-4-6l-4-7l-242-amc.html. Still have to do alot of figuring for the cam and top end, but I figure I will get the block machine work done and get the rotating assembly put together.

Anybody got advice on a good cam? Thoughts on running the 96+ stock OBD 2 cam?


thinking I can get by with stock according to this modified recipe 4.6L "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
Stock 4.0 camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" 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
248hp @ 4900rpm, 306lbft @ 3250rpm ('87-'95 camshaft)
245hp @ 4800rpm, 315lbft @ 3000rpm ('96-'04 camshaft)

NEW: Modified "poor man's" stroker

Same as above except Jeep 4.0L 6.125" rods, Keith Black UEM-IC944-020 forged pistons, and 0.070" quench height. This is a great stroker build for a mild supercharger/turbo application with up to 6psi of boost. The 4.0L connecting rod/IC944 piston combination offers 155g less reciprocating mass than the 4.2L rod/677P piston combination (1275g v 1430g), thereby giving this engine a potentially higher rpm capability than the traditional "poor man's" stroker.
 
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The stock cam will do just fine. But if you want a little extra grunt (in whatever power range you desire) I have had great luck with Schneider Cams and the Comp 231 series cams in 4._ engines.
 
Lee said:
thinking I can get by with stock according to this modified recipe 4.6L "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
Stock 4.0 camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" 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
248hp @ 4900rpm, 306lbft @ 3250rpm ('87-'95 camshaft)
245hp @ 4800rpm, 315lbft @ 3000rpm ('96-'04 camshaft)
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This is pretty much exactly what I have, minus the 24lb/hr injectors, and I used H802CP pistons I believe, but I'm super happy with it.

I'd definitely recommend going with the 4.0 rods and the different pistons though, which you may have done, but I'm too lazy to look at the link you posted :D
 
More compression equals more power. I say do it!
 
Sampling of some of the parts that arrived today. Decided after much research to deck the block .020. Run the .043 head gasket and the stock cam.
 

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I went with a similar setup KB pistons, 91 crank, 4.0 rods. Decked the block to .007, .043 gasket. So, quench height of .05. Ford injectors work great. jeepstrokers.com is a great resource. Read, Read and then read some more. Lots to learn.

FYI- I had to index the distributor to get it timed right.
 
Jeep strokers has been a wealth of knowledge. I have read for days and kind of deciphered the way this build will fit my needs and budget best. Your setup sound very similar. I will end up with a .051 quench. What can are you running? How is the performance difference from the 4.0?
 
Cam- CompCams 68-231-4 206/214 degree camshaft.
Lifters- Comp Cam 822-12
It seems like there are other cams out there that people like better. My stroker does have a slight tick- I think it is in the valves. I used rocker spacers to get the preload on the pushrods. Building an engine is definitely new for me, so I might not have it perfect.
Throttle response is awesome. The power gain is good. I have been told that I will get a more from my setup if I increase the diameter of my exhaust.
I went with Joe Gibbs break-in oil. Who knows if it was worth it or not.
 
After further inspection of my stock cam I have decided to buy a new cam. Chose a comp 68-200-4. Looks like I will be able to run stock valve springs with only .433 lift. Calculator shows with my setup I will be at 9.43 scr and a 8.25 dcr. Hope to pick everything up from the machine shop Thursday and assemble the engine next weekend
 
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Mac5005 said:
Can I ask?

If decking the block would lower the quench volume, then wouldn't that raise the compression ratio?, and wouldn't that in turn make detonation and pre-ignition worse? Or am I missing something. Please explain.
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I'll give the "sore back from wheeling and the Panthers are on" answer.
With some combos, like stock 4.0 pistons on 4.2 rods, the top of piston travel ends up quite a bit from the deck. This can allow excessive carbon buildup on the top of the cylinder wall. That buildup can create a "hot spot" and cause pre-detonation. This one is very common in "poor man's" stroker 4._ builds.

Also, there is this: (copy and pasted)
Quench (or squish) is the stirring up of the charge during the compression stroke. As the piston approaches the cylinder head, the charge between the piston and the head is squished out into the combustion chamber, which stirs the charge to increase the burning rate. If the quench clearance is increased, the squish velocity will be less, and the stirring of the charge will be less. That would slow down the burn rate, giving more time for the detonation to take place.
 
Jody Treadway said:
I'll give the "sore back from wheeling and the Panthers are on" answer.
With some combos, like stock 4.0 pistons on 4.2 rods, the top of piston travel ends up quite a bit from the deck. This can allow excessive carbon buildup on the top of the cylinder wall. That buildup can create a "hot spot" and cause pre-detonation. This one is very common in "poor man's" stroker 4._ builds.

Also, there is this: (copy and pasted)
Quench (or squish) is the stirring up of the charge during the compression stroke. As the piston approaches the cylinder head, the charge between the piston and the head is squished out into the combustion chamber, which stirs the charge to increase the burning rate. If the quench clearance is increased, the squish velocity will be less, and the stirring of the charge will be less. That would slow down the burn rate, giving more time for the detonation to take place.
Click to expand...


Haha. Thanks man
 
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