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Re: Another 4.6 Build
Posted: June 12th, 2008, 2:10 pm
by Flash
gradon wrote:tsk-tsk
.............................................................Sounds like some one got the clock working again
Re: Another 4.6 Build
Posted: June 12th, 2008, 11:16 pm
by gradon
gotta give ya some ish.
Re: Another 4.6 Build
Posted: June 13th, 2008, 1:46 am
by Cheromaniac
Geo. wrote:First I would like to thank Muad'Dib for the site & all the regulars (I would name them, but I am afraid I would leave some one out) for all the time, effort and knowledge contributed to this forum and the Stroker list before.
I have been lurking and learning for over a year now and am finally starting to put together my own stroker. It will be for a 95% trail rig with an auto, so torque at low rpm for big tires (40") is my goal.
Parts on hand:
91 4.0 block & head
re-conditioned 258 rods
silvolite 2229c pistons
comp cams 68-231-4 & lifters
Mopar 5249464 springs
Mopar .043 head gasket (set)
I was hoping to take the block and head in for machining next week and looking for help on a few things. I am going to have the pistons dished, I would like to end up with 30cc's but have read that 24 cc's may be the safe limit. Anybody have any experience with this?
If 24cc is the max and I deck the block .035 and the head .010 I end up with 9.25 SCR and 8.378 DCR and a quench height of .0575 if I have used the calculator right. Is this too high for pump gas? The alternative is to take less off the block but this increases the quench.
Assuming I do deck the block and head I need shorter push rods or adjustable rockers, correct? If I chose adjustable rockers, I need a valve cover spacer?
Or should I wait to see how the KB 944's work out and start again?
You're already on the right track. All you need to do is dish your existing pistons. The 2229's come with an 11.5cc dish but you only need to go as high as 22cc and do an almost exact copy of the 4.6L low buck stroker option 2 recipe (except for the cam) that I have here:
http://jeep4.0performance.4mg.com/stroker.html
The specs would be as follows:
Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Silvolite UEM-2229 +0.030" bore pistons
Increase piston dish volume to 22cc
9.5:1 CR
CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mill block deck 0.035"
Mopar/Victor 0.043" head gasket
0.058" quench height
Ford 24lb/hr injectors with adjustable FPR or MAP adjuster for '87-'95 engines
263hp @ 4850rpm, 324lbft @ 3500rpm
This static CR assumes a head with 56.5cc chambers. If the chambers turn out to be bigger, this will lower the CR and allow you to use lower octane fuel with slightly lower HP/TQ outputs.
Re: Another 4.6 Build
Posted: June 17th, 2008, 6:37 pm
by Geo.
Bad news, the block was worn beyond service limits.
Good news, looking through the local buy-sell for a block and scored a 97 XJ with blown tranny for $800.00! It's too nice to part out so my crawler is on hold while I build this for a DD.
The best of both now, 96+ block and 7120 head.
Engine shop is machining the pistons and re-building the head while they wait for another block.
Re: Another 4.6 Build
Posted: July 8th, 2008, 4:41 pm
by SilverXJ
Nice find. Throw a tranny in and drive it.
Re: Another 4.6 Build
Posted: July 10th, 2008, 8:32 am
by Geo.
I just bought an rebuild kit for the tranny, if I screw it up I will just pick up a used one for $69. at Pick a Part, I love how cheep these things are to play with!
The machine shop has mocked up a piston and says I am .056 below deck. I told them to deck it .040, this gives me a quench height of .059.
So, if I subtract .043 (new head gasket) from .052 (stock thickness) = .009 I am decking the block .040 and the head needs .005 to clean up. That is .054 shorter than stock, stock push rods are 9.641 less .054 = 9.587 The closest pr listed on the push rod faq (I love this site!!!!) is RP3171 at 5.954". That is only .007' longer than stock geometry, close enough?
Re: Another 4.6 Build
Posted: July 10th, 2008, 11:40 am
by gradon
You meant they are 9.594". I had .030" taken off the block and .004" taken off the head, but am using a PR that is .037-39" shorter than stock(looks like stock replacements can be 9.639-41"). I don't know what is an acceptable tolerance +/-, if it's better to err on the shorter side(maybe not as much lift--.445" instead of .45" in my case) or the larger side(extra preload?) in your case. Regardless, it's better to be .007" long than .054".
Re: Another 4.6 Build
Posted: July 10th, 2008, 1:43 pm
by Geo.
Back asswards as usual, yes I meant 9.594, thanks.
The engine shop says they routinely surface heads .005 - .010 and just pop them back on with the old push rods, so I think I should be alright.