Vehicle: 1996 Legacy L wagon EJ22 (soon to be Frankenmotor)

2nd owner, just passed 200k miles (mostly highway grandma-style driving. Never overheated.)

Very regular oil/filter changes; Mobile full synthetic 0w-30

 

 

 

The motor has developed a lifter tick. It is sporadic yet consistently there. Mostly does it while at opperating temp. So since I'll have the motor out to service the valves, I figured I'd drop in a 1996 2.5l block that has 171k on it.

 

My main topic of interest/question.. I ordered the ej25/22 hybrid cometic gasket yesterday (100mm x .040" I hope that's correct...Those are the specs I've read everywhere for this application). This is before I've serviced the heads. I plan on resurfacing the heads via the shop bench-glass-sand paper-wd40 method. Did I just waste +$100 buying the gaskets first? Will I need thicker gaskets because of the loss of material during the resurfacing? I thought I'd be fine because 1.) motor has never overheated, 2.) this is the first time the heads will have been removed, ever.

 

Let me know so I can either relax or sell these and order a new pair...

 

Greg

Edited September 30, 201411 yr by suprunner

Removing material from the heads isn't the issue here.

The 96 block is a "peek-a-boo" block. The pistons crest above the block deck at TDC. You need a thicker head gasket to keep the pistons from striking the head. I don't recall the thickness needed for that block but I know that's the major issue with using the 96-97 25D block.

Removing material from the heads isn't the issue here.

The 96 block is a "peek-a-boo" block. The pistons crest above the block deck at TDC. You need a thicker head gasket to keep the pistons from striking the head. I don't recall the thickness needed for that block but I know that's the major issue with using the 96-97 25D block.

Thank you for the heads up. I called cometic, and they were thankfully able to hold my order until I get the correct info. If I pull off the heads for the 2.5, would I be accurate if I were to measure the distance that the piston moves outside the block?

I called a few different subaru dealers to see if they have any dimensions for a '96 ej25 block... No one seems to be able to find a thickness for the headgasket, or know of those motors having the pistons move out more..

 

 

EDIT: Just got a call back from a dealer in my home town. I think this kid was new or something but he actually grabbed one off the shelf to measure for me. .055" thick. I'm assuming I'm safe with that number? Maybe go .056"?

Edited September 30, 201411 yr by suprunner

The pistons crest out of the block the same on all ej25d's . But the piston is different, you will have much higher compression with that bottom end than 97-99 blocks. With stock thickness gasket you will have 11.4:1 compression, you'll be safe as far as piston to valve contact. But you will have a high risk of detonation.

If I'm using 91, will there be detonation problems? I'm also doing everything stock. I'd like to tinker on this project for a while. I plan on adding delta ground cams much later. By then I'll need some ECU management...Should I get thicker than .055" to lower the comp? How would I calculate conpression ratio based upon gasket thickness? Cometic said they'd jump a little in price if it was .020" above .040"( my original/incorrect order).

Basically what you need to know is bore and stroke (99.5x79mm), combustion chamber volume (41cc), piston to deck height (.05mm above for ej25d), piston dish (-8cc for 96) the variable will be the head gasket thickness (convert the measurements to metric for accurate results).

 

Plug your numbers into this one. Just make sure to select the metric setting up top.

http://www.csgnetwork.com/compcalc.html

 

Also, consider that if you go too much thicker you'll be affecting your timing as all components are designed around stock measurements.

Edited October 1, 201411 yr by 86BRATMAN