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Guest Message by DevFuse

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ej25 dohc with sohc heads

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6 replies to this topic

#1 imprezadude



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Posted 20 August 2013 - 06:35 PM

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

#2 idosubaru


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Posted 20 August 2013 - 08:18 PM

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.

#3 imprezadude



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Posted 20 August 2013 - 09:18 PM

thanks for that gaskets are what others have said  the pcv system on the 00 up are threaded in the block  the 99 down stuff the pcv is threaded into intake im gonna rigg it  

#4 nickb21


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Posted 20 August 2013 - 09:34 PM

2000 (at least Legacy L's) had the pcv in the intake, not that it helps you. Isn't the intake threaded anyway with the hose nipple, maybe same threads as as the pcv?

#5 johnceggleston


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Posted 21 August 2013 - 06:50 AM

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, 21 August 2013 - 06:51 AM.

#6 ivans imports

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Posted 21 August 2013 - 10:08 AM

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

#7 johnceggleston


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Posted 21 August 2013 - 01:58 PM

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, 21 August 2013 - 01:59 PM.

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