BBC casting #1X157129AC still a mystery.

[Dwight Southerland]

Originally Posted by Jim Cimarolli

Is that an open or closed chamber head? What spark plug does it take?
I knew you said it had a 2.25 intake valve, what size exhaust valve?
Thanks, I wonder if Dwight Southerland can chime in on this one?

Jim - I can't shed a lot of light on this that hasn't already been said. The CFD marking indicates to me these are from the '80s. Maybe this was done at the same time the replacement 291 closed chamber heads were done. I know the late casting 291 heads (which were also CFD castings from the '80s) used the same intake port and exhaust ports as the 188 & 990 heads and were machined for the 5/8" spark plugs. What throws me is the 2.25" valves. Chev had 2.30" valves in their HP catalog about that time, but not 2.25" valves. It would be nice to have a bunch more pictures.