so I am thinking that to save a bit of money, I will try and freshen up the 100k mile ej25 SOHC heads I just bought rather than send them off to CCR. the valves/seals do not look to be burnt(surprise surprise). I am DEFINITELY getting new valve springs as I will be putting the hurt on them with a garrett. I do have a compressor.

I have had 16v motorcycle heads apart, but never subaru.

a few things to discuss:

 

valve grinding compound:

how is it done and is it worth my time? chuck up the valves in a hand drill?

 

valve seals:

do I need a tool to do it?

 

valve guides:

will they even be bad? how to tell?

 

any other general tips for success?

Personally....something like what you're talking about is not an item I would recommend a DIYer with limited experience to perform.

 

I didn't even bother when I did my motor. Even if I would've done the heads myself, I probably would have still taken them to a machine shop to perform a valve job.

from what I understand, valve grinding is a pretty common thing to do, I have experience with complicated heads, and I doubt the heads really need a full 3 angle job, so what could go wrong?

well I am going to do the lapping compound.

seals should be the standard pull the old ones out with pliers and seat the new ones with a deep socket right?

You're a person after my own heart!

 

Assuming you just want a "freshen up" and there are no major problems with burnt seats and/or valves:

 

Mark the valves so that they can be returned to their original locations.

With a wire wheel, clean the carbon from the front and rear of the valves.

Put some fine grinding paste on the contact area of the valves and seats.

Insert the valve into its guide and chuck the valve stem into a cordless drill from the top. Spin the drill at slow speed and pull upwards slightly on the drill to apply pressure on the seat area. Stop when you have a nice contact finish on the valve and seat.

 

Test the seal with some kerosene or other thin liquid pooled in the combustion chamber with the valve springs installed and the heads upside down. The valves should hold the kerosene for quite a while.

 

There shouldn't be much noticeable looseness with the valves fully inserted into the guides. If the guides are worn, note the installed height and drive the old ones out. Freeze the new ones in the freezer. Heat the head to 400 degrees in the oven. The freezing cold guides should almost fall into the hot head with just a few taps of the proper sized socket.

 

Valve seals? You know what to do...........Pliers for removal, socket and hammer to tap them on.

get a good valve spring compressor. i bought one from advanced auto parts and it's a POS for the older subaru motors. does not work well, if at all and is dangerous having lack of control with all that pressure.

I have a nice one, its homemade out of a very large C clamp and pieces from one of your crappy autozone compressors! it works very well on stiff motorcycle springs designed to rev way higher than any street EJ motor.

scoobaru, good tips thank you sir.

but I think I am going to forego the drill trick and just use the hand tool as I do not want to risk compromising the valve guides in any way.

I used the hand tool at first, then put the small suction cup onto a dremel arbor for a sanding drum and chucked that into my drill. Saved me a bunch of time.

 

Jay

Valve job is no that hard, but the ppoint of the valve job is refinishing the seats. Valve grinding compound is not what that is used for. It is actually for lapping the valves, This is done with a suction cup tool to ensure a perfect metal to metal seal, its the final step, not the first step.

Taking the head apart is simple. But if your not going to bother with a true valve job (and three angle isnt that hard to do with the right tools) then you may be doing alot of work for nothing.

 

nipper

Respect to anyone willing to give this a go, but i'd have to agree with nipper. Its a complex job so get it done right first time and good luck!

 

KELTIK

well, these are 100k mile heads. I suppose I will first test the leakage and then reevaluate. the reasoning behind wanting to do a lap is wanting to change the seals and not wanting to pay a machinist. but, I have not really looked into the labor for a valve job. that is ALL I am willing to farm out on the heads for this build(payed $450 for ej22e head rebuilds 1 year ago).

comeplelty disassemble the heads yourself. that will save labor charges. Also another thing the machine shop does is knurl the guides so there is no oil consumption.

 

nipper