302 valve seals

[DBoyer0]

I'm suffering some confusion here. I took off the heads from my 88 Mustang 302 and removed the valves and springs. The right side head had different seals than the left. I'm presuming that this is a sign that some work had been done to one head and not the other. Don't know which one though. The right side head had a plastic valve stem seal/retainer on the exhaust valve and a different rubber valve stem seal and metal retainer on the intake valves. The left side had the same type seals on all of the valves.

[83GLCoupe]

From what I understand is that the rubber with metal band style is stock for the intake side and an umbrella style is stock for the exhaust. Since the umbrella style isn't that good, there is a style of seal similar to the intake side but for the exhaust to seal better.
I'm in the process of rebuilding my stock E7's and are planning on that style for both valves for better oil control.

[DBoyer0]

Thanks, I'm still baffled on why one head had all the rubber and the other head had both.

From what I understand is that the rubber with metal band style is stock for the intake side and an umbrella style is stock for the exhaust. Since the umbrella style isn't that good, there is a style of seal similar to the intake side but for the exhaust to seal better.
I'm in the process of rebuilding my stock E7's and are planning on that style for both valves for better oil control.