Refurb Subaru EJ205 Cylinder Heads - Should I face mill them?

[HoosierBuddy]

Hey guys,

I've been working on a bit of a "social distancing project"...in that I seem to have a lot of time on my hands these days.

Project involved tear down of my kid's WRX's 115,000 mile OEM engine that we replaced a year or so ago because of low compression in one cylinder. Well, I think I tracked that problem down to a crack in the #1 piston allowing compression to leak by the rings. It likely makes no sense to rebuild short block, because you can buy this short block brand new from subaru for 2 grand...and just the parts would be close to $1000 (gaskets, pistons, rings, bearings, oil pump, timing set, etc) PLUS machine work.

So I was thinking I'd just refurb the heads and box them up to use as spares if the replacement (used JDM) engine takes a dump. And then sell them down the line if he gets rid of the car in a few years.

My plan is to disassemble them, clean and evaluate the valves, replace the valve seals and probably springs...and reassemble. However, I've got a milling machine (an old U.S. Burke "Millrite") and these little bitty heads (the EJ205 is a flat 4, meaning each of the 2 heads only serves 2 pistons)...would fit on my table. You see where I'm going here?

Would it make sense to take a skim cut on the combustion chamber side of these heads? If so, would a fly cutter be the tool or something else? OR...would you recommend just letting sleeping dogs lie and NOT resurfacing. There are no visible defects on the head face. Just trying to be a little thorough here.....ESPECIALLY if on down the line I end of selling these to someone else.

Phil

 

[bpjr]

What are the chances you will ever use them again I wouldn't waste time or money unless you are going to use them. Make the decision when you need to use or sell.

 

[General Geoff]

If you want an excuse to make chips, sure, go ahead. But if you're concerned with practicality, check the cyl heads with a straight edge before proceeding.

 

[metlmunchr]

Unless you have a valve machine and seat grinder, there's not much point in doing anything else to the heads now. A set of heads with various new parts but no valve job has no more value than any other set of used heads to a purchaser who's knowledgeable enough to do quality engine work. The ones who wouldn't care are the same ones who are looking for heads they can buy for 20 bucks apiece to complete a quick and dirty hack repair.

 

[Mr_B]

heads don't warp on those in general .
Best checked with straight edge and if in spec just clean surface up to high standard .
main issue on those is cam journal wear .
No point skimming unless truly needed .

 

[got2boostit2]

If no cracks around spark plug holes look at refurbishing. Straight edge check and then skim cut to clean up. Rebuilt 205 heads were going for $600-800 on Nasioc last check. Or keep as backup. People reuse heads with cracks around spark plug holes without issue, but lots of people balk when seeing the cracks. NASIOC forum is a good resource.

 

[HoosierBuddy]

Thanks for the insights guys!

I will evaluate the head face with a straight edge before proceeding. Once I get the heads disassembled I will also evaluate if any of the valves or seats have visible wear or issues that would require a valve job.

My understanding is that if a valve job is required on these heads then the bucket shims have to be adjusted accordingly, which may be a steeper learning curve than I want to tackle.

Got2boosit2....agree 100% NASIOC has been an invaluable source for us, especially when we were evaluating the old engine and doing the JDM swap. I keep coming back to the fact that if I would have had a good used set of heads at the time...I could have gotten that brand new short block rather than doinking around with a used JDM engine. It worked out OK...but I'd have rather had a new short block.

Phil

 

[c39er]

Milling the heads would somewhat affect tensioner and TB belt too.
Milling the heads on old Datsun 1600 and 2000 Fairlady's and pickups sometimes required a thicker head gasket to keep the chain in spec.
https://thefactoryfiveforum.com/sho...-with-a-Decked-Block-Milled-Head-Flat-4-Motor

 

[ChrisLS8]

Milling the heads would somewhat affect tensioner and TB belt too.

Not to any degree you would ever notice

 

[Showkey]

If I was going to redo the heads, I would have checked for cracks, cam bearing clearance, , guides, seats ........I would then do this: