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Home "machine" Subaru 2.5 heads


Aug 22, 2015
I didn't say he was.

Another way to look at it is if the average machine shop - even a good one - can't meet the specs called for to refinish the head* surface then it's a shaky design, too.

*And the head would never have needed to be in a machine shop in the first place if it hadn't been designed in a marginal manner.
The order of failure is gasket leaks-> engine overheats-> heads warp due to heat. Head design was not the cause of the failure.


Cast Iron
Mar 31, 2013
Danville Virginia
One thing to consider when doing a VJ on a Subaru is the expense of valve adjustment after the valve job. Later heads use solid buckets of various thickness, no shims, time consuming and pricey. On a side note, for the past 8-10 years I did all the block machining for the US Subaru rally team featured in the video in post 39 (until retiring this year). Stock blocks were not up to the task of big HP so several years ago they went to billets. A lot more work to get to finish form but they hold up under 50 lbs boost.

Edit: I should add that a good automotive machine shop will have a surfacer with a PCD insert, they give the best finish of about 12-15 Ra.


Hot Rolled
Apr 14, 2012
New Zealand
Subaru's are a sorta the Mercedes of Japan. They have this (sort of) reputation as being super-rugged when in fact they are far below the norm in terms of reliability. Somewhere, someplace, a marketing genius must be rolling in the dough.
I ran away from Subie about the time they went away from pushrod operated valves to that f'kn stupid long rubber band drive.
Bought a SR20 Nissan Primera and later an R32 Skyline and never looked back.

I always wondered if a Lycoming would fit??
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Dec 21, 2012
Brisbane Qld Australia
I would always check out the price of new made Chinese heads ,new cams ,valves ,the lot ...........I went the new head with my Ford ,three day turnaround (thats with my creaky bones ).......the local cylinder head service would have been a week wait ,and my old stuff back refaced ...........the Chinese head is the most beautiful bit of machining ever seen by me.......and the whole lot ,bolts ,gaskets,delivery ,etc ,was around 1/2 the price of a head exchange from the locals.