Head bolts; 1.5 vs 2F what's the difference and why? (2 Viewers)

[Pighead]

I pulled my cylinder head the other day, routine valve job, 4 of the head bolts have washers, 11 are shouldered. They look pretty much the same otherwise.
What is the actual difference between the Late F and the 2F head bolts? Why are they different? Is the difference in the blocks or in the heads?

 

[charliemeyer007]

No clue. When I do mine I'm going to chase the threads in the block. I like washers, as they can "slip" easier when torqueing IMHO.