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Old 04-25-2011, 08:49 PM   #1
ilikesubaru:)
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Default Single Cam Block with DOCH Heads?

Hi everyone, I have a question for all of you engine geniuses. My friend have a 99 legacy outback with 2.5L DOCH engine, he got a rod knock in it. So he decided to just put a new block from a 2001 outback with 21k miles on it. The only concern is that the new block was originally single cam. My question is will the 99 legacy 2.5L DOCH heads fit the new single cam 2001 outback block?

My other friend did put a block in his 97 legacy a from 07 impreza and he had to put different pistons in the block in order for 97 heads to fit the 07 block. Is this true with 99 heads and 2001 block? Please let me know. Thanks
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Old 04-25-2011, 09:49 PM   #2
Patrick Olsen
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The '99 DOHC heads will bolt onto the '01 Phase II block without any issues at all. Use the DOHC head gaskets to get the proper compression ratio.

Not sure why your other friend had to put different pistons in his '07 block - I've never heard of such a thing. What exactly was the issue, and what pistons did he put in it?
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Old 04-25-2011, 10:59 PM   #3
ballitch
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I say use the 01 block with SOHC EJ25 headgaskets and enjoy the 10.5:1 compression ratio.


~Josh~
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Old 04-26-2011, 03:02 PM   #4
ilikesubaru:)
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Quote:
Originally Posted by Patrick Olsen View Post
The '99 DOHC heads will bolt onto the '01 Phase II block without any issues at all. Use the DOHC head gaskets to get the proper compression ratio.

Not sure why your other friend had to put different pistons in his '07 block - I've never heard of such a thing. What exactly was the issue, and what pistons did he put in it?
On his 07 he had the bubble head pistons which hit the DOCH heads and they would no bolt up it was like 1/4 of inch gap between the DOCH head and the block, so he bought the DOCH flat head pistons and installed into the block then the DOCH heads bolted right up to the SOCH block. Thats my question if the 2001 SOCH Block has those bubble pistons, if it does I just dont wanna buy new pistons and install it to the block. Also how can I tell the difference between the phases of the block? I just dont know much about them. Thanks
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Old 04-27-2011, 09:55 AM   #5
Patrick Olsen
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First, you're killin' me with "SOCH" and "DOCH". It's SOHC (Single OverHead Camshaft) and DOHC (Dual OverHead Camshaft).

Second, I've already answered the question - the DOHC heads will bolt onto an '01 block without any issues.

An '01 block is a Phase II block, there's no differences to determine.
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Old 04-27-2011, 11:53 AM   #6
ilikesubaru:)
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Quote:
Originally Posted by Patrick Olsen View Post
First, you're killin' me with "SOCH" and "DOCH". It's SOHC (Single OverHead Camshaft) and DOHC (Dual OverHead Camshaft).

Second, I've already answered the question - the DOHC heads will bolt onto an '01 block without any issues.

An '01 block is a Phase II block, there's no differences to determine.
Thanks for your help, I don't know why I'm killing you, I just tried to explain as much as a could because my friend had problem with an 07 block Anyways thanks again.
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Old 04-27-2011, 01:11 PM   #7
Patrick Olsen
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Your explanation is fine. What's killing me is that you're repeatedly getting the acronym wrong. There's no such thing as "SOCH" or "DOCH".
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Old 04-27-2011, 04:18 PM   #8
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Isn't that Irish for Socks and a boat dock???

I'd like to see those 07 pistons.....

Jay
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Old 04-27-2011, 04:23 PM   #9
Matt Monson
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Those new 2.5i pistons are funny looking little things. They actually look a lot like an old 911 air cooled piston from a CIS engine...
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Old 04-27-2011, 04:47 PM   #10
ilikesubaru:)
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Quote:
Originally Posted by Patrick Olsen View Post
Your explanation is fine. What's killing me is that you're repeatedly getting the acronym wrong. There's no such thing as "SOCH" or "DOCH".
Crap I'm sorry just was in the hurry trying to write this to get the response faster. Tomorrow we will pick that 01 block from the guy and install it on my friends legacy, thanks again.
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Old 04-27-2011, 04:50 PM   #11
ilikesubaru:)
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By the way so should I go with SOHC head gaskets and DOHC heads to get more compression, or I just should stay with DOHC head gaskets? Will higher compression ratio effect the gas mileage. Thanks guys
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Old 04-27-2011, 11:40 PM   #12
ballitch
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Gasket matches the block, always.

So use the SOCH gasket.....

That's just for Pat.


~Josh~
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Old 05-01-2011, 04:39 PM   #13
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I've replaced the SOHC 2.5L headgaskets with STi HGs. I rather them not leak down the road like they still are.
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Old 03-21-2019, 09:28 PM   #14
Carlos2003
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Default Does the same thing go for 98' DOHC heads on a 02' SOHC block? Im

I heard that it ups the compression one whole point from 10:1 to 11:1, that is if you use the SOHC gaskets. I just wanted to make sure that there isn't any clearance issues.
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