Does Subaru make heads 2 different size exhaust ports?

 

Here is the situation, I bought a rebuilt engine a few months, car is an '04 Outback with 2.5 engine. Everything went good, car was running good. I started getting a slight exhaust leak at the manifold, enough to cause a po420 code. I ordered new gaskets but while putting them in I realized that the ports in the heads are bigger than the manifold, the studs line up and the gasket will go on but the flange does not cover enough of the gasket. The gaskets they sent with the rebuilt motor are the same, I didn't notice it when I installed the motor. It seems like I am going to have to replace the manifolds which really sucks. The way it is now the flange is actually restricting about 25% of the flow.

 

I hope I explained this well enough to make sense

Edited July 14, 201213 yr by richinct

The exhaust ports are the same in all non-turbo dual engines.

Clean the header flanges and head ports with a rotary tool to get them as clean as possible before installing new gaskets. The dealer gaskets have a ripple side and a flat side, the flat side should go towards the head iirc.