Bought 2 Olds 350 engines..

[GMNorway]

From OLDS FAQ : For those seeking to build a really heavy-duty engine, rumor has it that the blocks with a "F", "F1", etc, up to, "F5" or "F6", are higher in nickel, and stronger. Rumor has it those blocks up to the "F2" are the most desireable. These are commonly 1967 to 1970 or so 425 or 455 blocks..

Dont know if it is same for the Smal block engines..

 

[79loserbluebu]

From what I have been told and read, higher nickle is more brittle, but also less likely to need boring, in other words, its a harder cast. Im not sure it would make a better race engine, but it does make for a longer lasting and more durable street motor. IIRC, the army used engines with chromium/nickle blocks that would literally last forever in the 2.25 trucks back in the day.

I see. Oh well, you won't be able to tell the difference between the two once it's assembled and in the car.

 

[hurst1979olds]

http://www.youtube.com/watch?v=oJOvfaoZpB8
This is what can be done with a Diesel block. Mine is a 350D.