Numbers on intake and exhaust ports(MC-1)

[Michael Gough]

> [ Picked text/plain from multipart/alternative ]
> I just removed the head off the MC in my turbo Coupe GT, after a very bad
> weekend.  I noticed in the intake and exhaust ports that there were numbers
> stamped in them.  They were values in the 13 to 20 range.  What are they?

I noticed that too on my MC head when I was matching the ports...my numbers
were in a lower range though....I'd love to know what they are for too.
Mike