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workin a 03 sohc and want to use a 99 dohc short block with the 03 sohc heads on it  any body done it  pistons apear to have a lower compression with obvious square top not sue about piston clearance and also pcv system has tube in 99 the 03 has a threaded fitting any remedys

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i've done it, use thick headgaskets or i believe the pistons can strike the heads. with thin headgaskets they won't strike the heads when assembled but will when running.  may vary depending how much material has/will be taken off for resurfacing.  forget which headgaskets i used but it may have simply been the 610 gaskets (last 3 digits of the Subaru part number for the DOHC heads).


PCV is easy, i don't remember having any issue with it so just use the 99 hose if the 03 fitting doesn't look to swap, which i don't remember doing. it's just hoses, compared to a short block swap that's a drop in the bucket, you'll figure that out.

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the 99 block is a phase 2 block, but as mentioned, the pistons and possibly the rods are phase 1.

the crank has to match the block since they moved the thrust bearing around then.

 

i doubt they would change the thrust bearing position and the block and the crank one year just to come back a year later and change the crank again.

Edited by johnceggleston
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Must use thick headgaskets also must modify the tetioner as it will not have enuff room now i take the bracket fo it and drill the 3 holes biger so can move braket up to give more room for tentioner. Also the round pin that it sitts agiant i trim the bottom side flat by doing these two things the belt will not be to tight if not problems. Other than that i think there may be oil flow retrictions on twincam heads that are not on single cam heads this may cerate a oil preshure / flow problem. The two engines may flow oil diferently as one is end thrust and one is center. There is tiny oil retrictors in the pasage on twin cam heads

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the ej25 block in 99 is the phase 2 block that was used 00 - 04

 

from subarugenuineparts.com the block is the same 99 - 08

                                      

 

Engine, Cylinder block
All Models - 2.5l, 1999-08

ENGINE »Engine

Subaru › Outback › 1999-2001

List Price : $1,104.23
Your Price : $1,037.32       

Edited by johnceggleston
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