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Old 09-21-2010, 06:27 PM   #1
bugeyesubby
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Default Mix and Match block halves

Im trying to find out if its possible to take 1 half of a EJ257 and mate it with the opposite half off another EJ257?

Long story short I purchased a "Ej257 short block with fresh wiseco pistons" installed with only 200 miles on them. I was told that the block wasnt honed for the pistons cause it was a low miliage block and from what ive read forged pistons need more piston-to-wall clearance so before I put it into my car I decided split it and have it honed. Got the block back yesterday and 3 cylinders are perfect with .0040 clearance but #3 cylinder is at .0050 and have some spots where the honed didnt even touch.
I dont want to bore over to 100mm cause I already have the new forged wiseco standard size.
I want to either get another stock bore driver side half or sell these halves to someone lookin for a block to bore over and buy another bare block.
Thanks in advanve for the help


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Last edited by bugeyesubby; 09-21-2010 at 06:42 PM.
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Old 09-21-2010, 06:56 PM   #2
paintbing
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Yes but with PROPER machine work - You'll have to line hone the main journals at a minimum.

However buy the 100mm pistons and sell the ones you already bought. It'll be much cheaper this way.
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Old 09-21-2010, 07:04 PM   #3
Csquared33
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Quote:
Originally Posted by paintbing View Post
Yes but with PROPER machine work - You'll have to line hone the main journals at a minimum.

However buy the 100mm pistons and sell the ones you already bought. It'll be much cheaper this way.
a line hone is a must.
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Old 09-21-2010, 07:06 PM   #4
bugeyesubby
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Yea im Trying to keep my cost LOWWW lol cause my girlfriend just got laid off so less income for the household and more bills on me. thanks for the advice I never considered the machining of the main journals...THANKS
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Old 09-21-2010, 07:10 PM   #5
MartinSTi05
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What they said. If the mains don't line up you are hosed.
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Old 09-21-2010, 08:04 PM   #6
john 1badSTI
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to have the mains align honed is twice the cost of bore and hone because they have to take a skim cut of where the cases go together before align honing it= a lot of work.just bore it to 100mm and be done with it.
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Old 09-21-2010, 08:06 PM   #7
paintbing
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I forgot to add... If the block halves don't line up front to back then you're hosed as well cause you will NEVER be able to get the clearance correct on the thrust bearing.
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Old 09-21-2010, 08:37 PM   #8
bugeyesubby
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I dont wanna get the noob bashing but ive been against goin to 100mm cause I have read that if you are planning for over 400hp its better to stick with stock size bore..
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Old 09-21-2010, 09:43 PM   #9
john 1badSTI
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it is nice to stick with stock bore but I have tuned quite a few 100mm setups to over 500whp,a couple to almost 650whp.
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Old 09-21-2010, 10:45 PM   #10
bugeyesubby
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That's good to know... thanks for all the info so far. I'm def. Not gonna use another half with my good half cause its not woth the headache and money so I'm either going to sell this block and start over with another to save my pistons or sell my pistons to buy 100mm ones and have this block bored over. So far nasioc votes are for 100mm lol
Thanks again for all the help and advice

Last edited by bugeyesubby; 09-22-2010 at 10:55 AM.
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Old 09-22-2010, 12:41 PM   #11
06PrecisionSTI
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if u bore the bigges thing is watching how much boost u ran the stock bore starts to warp the cylinder walls at about 27 psi but other than that boring to 100 is a great idea but make sure that the machine shop has a deck plate for the subarus a deck plate is a must for boring the boxer motor. it keeps everything from warping while they bore. if a shop ever tells u that u dont need one they are dead wrong!!
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