Photo of Combustion Chamber of Head Casting 2843675?

66fs said
273 chambers are closed, similar to 302 heads.

The last year for the closed chamber heads is 67, they came on both the 273 & 318 that year... The 67 318 being the first year of the LA 318...

In 68 & 69 both the 273 and 318 have the same open chamber heads....