16v oversize valve seats

[oldeskewltoy]

(09-19-2016 10:52 AM)harkes Wrote:  I kinda knew it could be done, but is it necessary for, what essentially is a street car? Are the F/A engines running oversize valve seats?

every 4AG with Atlantic type O/S valve coming from Loynings uses O/S seats... some steel, some beryllium copper.

They run O/S seats so the the bowls can grow too....




Stock intake valve seats are just shy of 32 mm, while the exhaust seat is a little short of 28.5mm. Ferrea OS valves are 32mm, and 27.5. By the time you make the stock seats/bowls the same ID of the OS seats/bowls, the seat itself is too thin and may not stay in the head. Even a little bit of movement in the seat can cause catastrophic results