Chris' XJ stroker project

[Chris]

Hey guys, a little background first. I've got a 95 4WD XJ with a manual tranny which is used for a combo of DD/Offroad use. Probably more DD than anything though. I'm looking to build a stroker that is reliable, but doesn't cost a ton(aren't we all...lol) When finished, I would like an engine that can run on regular gas, but still has enough power to impress ME and my buddies. I'm not looking for anything too wild, but when I crank it up, I would like for the people around it to wonder what I did to it. A lope at idle would be nice! Been reading and researching other peoples builds, and started coming up with a possible wish list for my project. Ran some numbers through the stroker calculator at the top, and here are my possible mods and the numbers from the calc. Someone with knowledge PLEASE point out the error of my ways. I don't mind spending a little more, and having this take a little longer, if it is right in the end!!!

Donor engines
4.0 complete running takeout engine from a 93 XJ
4.2 shortblock for the crank and rods(Not for sure of the year or castings yet...I'm away from home when I found this, and won't pick it up for another 3 weeks)

Mods
Bore out the block .30 over
try not to shave any off the block or head if at all possible
Sealed Power pistons 677CP
Crane 753905 cam (lift .456int/.484ex duration 260*int/272*ex)
Crane valve springs CRN-753901 (1.437 in. O.D. 204lbs/in rate "1.069 in. Coil Bind Height)

When I added the numbers up in the calculator, here is what it gave me:

Bore - 3.905 (.30 over)
Stroke - 3.895 (standard number)
Deck Height - 9.453 (stock since I haven't shaved it down)
Head Gasket Thickness - .060 (stock is .051)
Combustion chamber volume - 57 (didn't know what to use, so I used the standard number)
Piston dish volume - 17.5 (no dishing on the piston, this is what they come as)
Compression Ratio - 9.15\:1 (stock is 8.76/:1)
Quench - .0985 (stock is .0725)
Quench diff from stock - -0.026
Deck clearance - .0385 (stock is .0215)

Help me decipher these numbers...are they even remotely close to what I need to be looking for, or what can I do to improve them? Thanks guys.

[seanyb505]

Youre going to want a smaller quench than stock. It helps with the combustion process. Low 9 CR is a good goal, but when you do something to lower the quench, say, shave the block, your CR will go up. A good way to take care of that is to dish the piston, which you might want to think about. Its kinda like a wild goose chase, once you fix something another problem will come up.

[Chris]

The quench numbers were in green....was this not what I need?

Nevermind, they are all in green...I see now. With the quench being soo little above stock, would this make a difference on the fuel I will have to use, or is it a "must" to get it down further? What would be the easiest way to get the quench down? Deck the block, and if so, by around how much? Also, by decking the block, won't I get into having to order custom length push rods or using spacers for the rockers?

[Chris]

Looked at the numbers with a different thickness head gasket. This raised my CR to high 9's, but now my quench is below stock. What ill effects with the higher CR have for my build? If I'm right, the CR is one of the main causes of having to use Super, am I right here? As stated before, I'm trying to do this on as much of a budget as I can while still doing it right. If I can get away without dishing my pistons, I would prefer to go that route, but only if I really need to.


Bore - 3.905 (.30 over)
Stroke - 3.895 (standard number)
Deck Height - 9.453 (stock since I haven't shaved it down)
Head Gasket Thickness - .032 (stock is .051)
Combustion chamber volume - 57 (didn't know what to use, so I used the standard number)
Piston dish volume - 17.5 (no dishing on the piston, this is what they come as)
Compression Ratio - 9.65\:1 (stock is 8.76/:1)
Quench - .0705 (stock is .0725)
Quench diff from stock - 0.002
Deck clearance - .0385 (stock is .0215)



Another question is about the cam. I have no experience with different cams in the 4.0. Is this lift/duration ration gonna be too aggresive, or is it gonna be just on the high side of fun?

[gradon]

In your case, I would at least use the .043" HG and deck it .020 (or the .051 HG and deck it .025-.030) and then you'll be right around factory quench. I was disappointed today to see that the HG I received was a fel-pro .051, not the Mopar Performance/Victor Reinz .043 that I ordered, so I have to deal with the BS on returning that.

[Chris]

In your case, I would at least use the .043" HG and deck it .020 (or the .051 HG and deck it .025-.030) and then you'll be right around factory quench.

I'm a noob at this and still learning, so bear with me. I haven't run the numbers you gave yet, getting ready to go do that, but what would be the difference in my last numbers and these? I was able to get my quench down to around (barely below) stock. Would it be the CR changing with your numbers? I'm getting ready to go run them, so I guess we'll see.

I was disappointed today to see that the HG I received was a fel-pro .051, not the Mopar Performance/Victor Reinz .043 that I ordered, so I have to deal with the BS on returning that.

That sucks, sorry to hear. good luck getting what ya need back quickly!

[Chris]

Ran the numbers you suggested, and my quench was better than stock, but the CR went way up. Here's what I got.

quench - .0615 (.011 better than stock)

but the CR went up to 9.83\:1

Is that gonna be better than the numbers I had? Isn't that getting the compression up a little high?

Tried decking .025 with the .051 gasket, and this got me to"

quench - .0645 (.008 better than stock)
CR - 9.77\:1

And by decking the block, aren't I gonna have to go with custom length push rods? If so, how do I figure the length I need. I know it will depend on how much I deck, and the thickness of the HG.

[seanyb505]

I was told you can shim the rocker arms up to .060".

[Chris]

I was told you can shim the rocker arms up to .060".

How do I figure on my shim size? If I use the last set of numbers here is how I think it would go. How much removed from the deck (-.025) + gasket thickness (.051) - stock gasket thickness (.051) = shim height. I'm just guessing on this formula, but it makes sense. If this is true, I would need .025 thick shims. Where can I get the shims from?

[gradon]

I just crunched your #'s and a .051HG with .020" taken off the block you would have a 9.67 SCR and your quench would be .0695--.003 better than stock. If you don't want to deck the block and go with the .043 HG, your scr would be 9.45:1 and quench would be .0815--.008 worse than stock. I think this option(677cps with the biggest dish of 17.5cc and the thinnest HG) would be best for the poor-man's stroker and would probably run fine on mid-grade gas.

[Chris]

I would rather not deck the block, but if needed, I would. Sounds like decking it is going to be the best way for me to go. I'm sure it would be better to get the custom push rods with this kind of setup, but is it "bad" to use the shims? What is the price difference between the 2, and is my formula earlier the way to figure the shims....or the different length pushrod I'll be needing for that matter? On a side note, I haven't checked with any maching shops yet, waiting till I get home to talk to em, any idea on price range I'll be looking at to bore it out .30 over and decking the block?

[seanyb505]

Well the stock headgasket is .052", so if you deviate from that you need to factor that into your shim size. Example: if you go to a .060" add .008 to your shim size. The kit I got only has .030 and .060 so .008 isnt enough to really make a difference. You if you deck the block or the head, just add amounts decked together and thats it. Example: deck the head .005 just to get it flat, and the block .025 to get a better quench, you would need a .030 shim size. If you decide to go with a custom pushrod, you would just take .030 off the stock length to figure the new length. As Im sure you can imagine, a 9 inch rod costs more than a .030" or .060" washer.

A quality machine shop quoted me $300 for decking, boring and honing. For all the machine work I was planning on having done: $770

[Chris]

A quality machine shop quoted me $300 for decking, boring and honing. For all the machine work I was planning on having done: $770

What other machine work are you looking at? I'm assuming polish the crank and surface the head and freshen it up? Anything I'm leaving out?

[oletshot]

Anything taken off the head to freshen would have to be taken into account on your shims.

[seanyb505]

Break down of prices:
Block work
-clean block and ports: $120
-deck block .045": $120
-bore and hone cylinders .030" over: $180
-magnafluxing included
-instal cam bearings: $40

Rotating Assembly
-recondition rods: $100 (Im getting new rod bolts so Ill need it)
-press pistons onto rods: $45
-grind crank (if needed): $165 (I dont think I need this my crank looks good)
-balance rotating assembly: $165

So everything for the block and not the head will be 770ish. They quoted me $300 for the head, and Carquest quoted $170. I felt better about getting quality work done so it would be right. Both places said the same stuff went into a head rebuild, so Ill probly go with carquest for that.