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Unread 04-23-2013, 09:13 AM   #1
daviddoughty1
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1987 YJ Wrangler 
 
Join Date: Apr 2011
Location: overbrook, ok
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2.5 to 4.2 to 4.6

My 87 is having a midlife crisis, I never was happy with the 2.5 so when I found a 4.2 drive train it was an easy decision to make the switch. No more 50mph uphill, no more internal slave, no more changing the ax5 everytime it breaks. After getting it all in and running I discovered that my "new" '81 4.2 out of a J10 had some internal issues. Tranny and transfer case seems fine but too much blowby for me to leave the engine alone. Pulled it and took it to my local machine shop/ motor guy who found several busted rings.
In the course of discussing options we ended up deciding to go with a 4.0 he had and build a 4.6. Should mate up with the t177 and be a lot more fun than the original 2.5

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Unread 04-23-2013, 09:55 AM   #2
bogleparsons
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Join Date: May 2011
Location: fayetteville, NC
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I'm jealous.
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If it's not supposed to move and does use duct tape.
If it's supposed to move and doesn't use WD40
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Unread 04-23-2013, 11:37 AM   #3
jsawduste
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2006 YJ Wrangler 
 
Join Date: Jul 2006
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Great, I just hope you doin`t go with the all to often advertised "Poor Mans" stroker
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Unread 04-23-2013, 12:28 PM   #4
daviddoughty1
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Not sure if it fits any of the stroker recipes , we're using the 4.0 block and head and the 4.2 crank and a new cam, bored .030. We have modified the 4.2 intake so I can keep it carbed { because I love simple} and will be using the stainless header that we got on the 4.0 donor motor. I can twist wrenches but I'm no motor builder so I leave the build details up to him.
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Unread 04-23-2013, 01:37 PM   #5
jsawduste
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Go here
http://www.jeepstrokers.com/forum/in...eaab77aec0fcca

Learn about the piston and rod combinations that will give you a zero deck and ultimately a .04x quench. The quench is one of the secrets to making a stroker run well.

FWIW I run a stroker but it is a little different then most.
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Unread 04-24-2013, 04:35 AM   #6
daviddoughty1
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Thanks, that site has a lot of stroker info. My crank was supposed to be done yesterday so I'll drop back by the machine shop and get some specifics on the parts list, how far he planned to deck and shave things, etc
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Unread 04-24-2013, 05:36 AM   #7
jsawduste
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Quote:
Originally Posted by daviddoughty1 View Post
Thanks, that site has a lot of stroker info. My crank was supposed to be done yesterday so I'll drop back by the machine shop and get some specifics on the parts list, how far he planned to deck and shave things, etc
Please post up what you find. Hopefully your engine guy is on the ball.

It sounds ignorant of me to be so generic of "make sure you use the correct combination of parts" without specifics. When I built me stroker there was little in the way of rods and pistons to choose from. Used Eagle H beam rods that were longer then the stock 4.0 (4.2 is shortest then 4.0 next is the Eagles) and then had custom pistons made to order. I knew I wanted a zero deck with just enough shaved from the block to flatten the deck surface and a relatively tight quench of the mid.040`s. Head volume was around 62 cc`s IIRC. Since then several compaines have introduced pistons for strokers but I have not kept up on the combinations. The guys on the strokers forum can help with that.

I like the 4.0/Eagles longer rods because of the rod to stroke ratio but also piston engagement within the bore at BDC. Be sure your engine guys checks/corrects for length as the factory rods are all over the place.

Not a big fan on Comp Cams. Quality control and cam/spring specs are not the greatest. Lunati`s have some good numbers but their ramp angles are a bit aggressive IMHO and the journal finish has eaten more then one set of cam bearings for folks. Hesco is a good choice.......Link below. If your going to run much more then stock lift roller rockers are a worthwhile investment. Mopar and Harland Sharp are strong considerations. Not a fan of the Terra`s.

LS1/LS6 vales/springs/retainers and keepers are cheap and effective. Worthwhile investments. There is plenty of meat under the spring pockets if your engine guys wants (he will need to in order to keep spring pressures down) needs to machine for spring height. Keep close to the factory valve sizes as anything much larger gets shrouded by the bore.

Hesco while not cheap makes some very good parts. Hesco was contracted by AMC/Mopar for their racing endeavors back in the day. Leee (yes 3 E`s) and Bennie know more about strokers then most anybody.
http://www.hesco.us/

The Hi Flow water pump has a machined vane rather then a simple stamped vane and flows much better. The Hi Flow thermostat housing is a worthwhile investment. Another is the Melling HV oil pump they sell. It is blueprinted (generic term) and also has a sqruiter (sp) for the cam gear/dist. Make sure the oil pump sets flat on the block. It is not common but sometimes the block has a raised machined ridge that needs to be flattened. In any case Hesco have parts you cannot get anywhere else and the proven track record of parts that perform.

Be cautious of anything written by Dino. Real nice guy whom does his best to help. He lives in the land of sand and his fuel is so much different then what we burn here as to not be comparable. Important when your working with the combustion process. He is good with numbers but has little actual proof to back them up. You will find plenty of theory but again little practical proven data.

Welcome to PM me if you want to yak. A quick search will bring up some specs on the engine I run as well as some dyno pulls.
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Unread 04-24-2013, 06:25 AM   #8
blown50
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The best advice I can give is to index grind the crank, I didn't and have different piston heights! I did my rods my self ( buddy has a rod machine) and all my rods are the same! Stay away from the comp stuff as stated! You will be thrilled with the power, I to run a carb, but the 32/36 weber is a touch to small! A Holley would be a better choice! I kept my compression at 9:1 and have no problem with detonation. Bullet has some good cams without a bunch of overlap as most comp stuff has got. You can pm me to if you want, as I have all my specs written down
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Unread 04-24-2013, 07:12 AM   #9
daviddoughty1
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The points you guys bring up is exactly why I found a motor guy that I have confidence in. I'm a tinkerer and the internal details are beyond my skillset. This guy rebuilt the numbers matching motor in my old vette several years ago for me and it's still a blast and dependable.[IMG][/IMG] Everything he's done comes with his reasons for doing it and I trust his 30 or 40 someodd years in the business. From what I've learned so far online he's spot on with using good parts and paying attention to the details.....we'll see before long I hope .
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Unread 04-25-2013, 07:31 PM   #10
daviddoughty1
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Picked up my motor today and I guess it's a 4.7 now... he found a place in a cylinder he didn't like while honing it so he took them out to 60. I could have some of this mixed up but I believe he told me " 60 over pistons { Keith Black ?} Deck was taken down 35 and 25 off the head , quench was 45 with the compression ratio around 9.1 . Cam was 258 or 268 ?? I hate to sound ignorant but most all of it was beyond me. I'm going to hopefully put it in this weekend and see what I've got.
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Unread 04-26-2013, 07:53 AM   #11
blown50
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Quote:
Originally Posted by daviddoughty1
Picked up my motor today and I guess it's a 4.7 now... he found a place in a cylinder he didn't like while honing it so he took them out to 60. I could have some of this mixed up but I believe he told me " 60 over pistons { Keith Black ?} Deck was taken down 35 and 25 off the head , quench was 45 with the compression ratio around 9.1 . Cam was 258 or 268 ?? I hate to sound ignorant but most all of it was beyond me. I'm going to hopefully put it in this weekend and see what I've got.
Yea it sounds pretty correct, he milled the deck to make up for the deck height of the pistons, milled the head to get the compression and quench where he wanted them, and used the cam to kill some cylinder pressure at lower rpm.
It should be a healthy improvement over what you had! Hope you get it fired this weekend, keep us posted
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Unread 04-26-2013, 08:54 AM   #12
rykemc
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Not sure if you know this or not but I am putting it out there anyway. Don't make the mistake I did and install the 4.2 flywheel. You must use the 4.0 flywheel.
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Unread 04-26-2013, 09:05 AM   #13
blown50
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Quote:
Originally Posted by rykemc
Not sure if you know this or not but I am putting it out there anyway. Don't make the mistake I did and install the 4.2 flywheel. You must use the 4.0 flywheel.
He's not injected so it won't matter
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Unread 04-26-2013, 09:15 AM   #14
rykemc
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Quote:
Originally Posted by blown50 View Post
He's not injected so it won't matter
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Unread 04-26-2013, 10:00 AM   #15
daviddoughty1
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Quote:
Originally Posted by rykemc

Thanks for the heads up but I'm hopin to not need the Cps stuff
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