EJ22/EJ25 Valve sizes, head swap

[Legacy777]

Just some info for ya I stumbled across.

This is from SubyTechMaster on nasioc (formerly i-club)

The Phase I head has a single cam contained in the head, 31mm Intake Valves, 27mm Exhaust Valves, valves angled at 15deg from center. Early years (90-96) have hydraulic lash adjusters and they didn't get roller rocker arms until '93 (Impreza) or '95 (Legacy). '93 Impreza and later, '95 Legacy and later, have EGR which makes the heads either right or left side. These heads usually have dual exhaust ports but may have a single exhaust port if it's a CA spec, TLEV motor.

The Phase II head has a single camshaft sandwiched between the head and a camcase, 36mm Intake, 32mm Exhaust. Intake valves are 23deg off center, Exhaust valves are 20deg off center, contributing to a swirl effect in the combustion chamber. They do not have EGR and so the heads can be used left or right. The only differance between 2.5L and 2.2L heads is the 2.5L has dual exhaust ports and the 2.2L is a single.

Yes, the people I know who have done this are using the stock Fuel Injection. Hence the pinging under certain conditions.

The head gaskets on all the Phase I motors were a heavy composite type until '97 when they went to adjustable valves/interferance motors. At that time they switched to a 3-piece metal head gasket which may appear thinner but is very durable. This is the head gasket you would get today, they superceded the #s.

Here's the original thread
http://forums.nasioc.com/forums/showthr ... EJ22+heads