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Hello everyone, I am preparing myself to rebuild an EJ25 engine in my 2006 Subaru Impreza 2.5i SOHC. I want to make sure my valves are at or near original factory spec. If all I do is lap the valves, I understand that I may need to readjust the stem height. Will this cause any problem with compression or timing? Is there a way to determine if I need to recut the 3 angled surfaces on the valves? If I buy new valves for this used head, it looks like I will need to lap them, but will they sit correctly in the head?


Is there a way to check the valve seats and check it's angles or is all this that I'm asking about for the machine shop to do?
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Hi AJ ;  Your 2006 probably has 200,000 miles or less ?  You will know when you are lapping the valves how good the seat is. Look for the grey line, if its solid and even all the way around your good to go.  I would not replace the valves unless they are not seating. Unless you are building a high rpm turbo rally motor, I would not worry about a three angle valve job or stem height. You would not take enough off with lapping to change anything. Compression nor timing will change.  If your pulling the valves yourself you will need a torx plus tp40 , the cam covers are tight ! regular torx will strip it. Also your valve spring compressor may have trouble fitting in the small area . If you are splitting the case then be sure to buy NEW subaru only sealing washers and o rings inside the case  or you may leak water into the oil.  On rebuild only put Japanese made parts in for timing components ... be sure they are not made in china !!!! you will be very sorry if they are. 

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Get the Factory Service manual for your year engine. That will have all of the specs needed or checking the valves and seats.


The biggest thing you're looking for is that the seat and the valve face have flat surfaces where they seal. If the seat is worn to a point or there is a groove in the valve then the seat need to be recut and the valve replaced. 

Lapping is generally only necessary when replacing a valve. If the valves all have nice flat sealing surfaces then I would not bother with replacing any. You will need to set the lash clearance after reinstalling the valves, and then you'll need to check it again after running the engine for a few weeks.

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