Thread: 1970's Block & Gen5 Heads?

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i have done it the f1047 up to 4.540 bore or f1037 for smaller bore the mark 4 block was started in 1965 as the 396 and was end around the late 80s this block has a closed down deck less holes in the deck making for a stronger and better block i think. the 5/6 blocks have a open up deck bigger holes for coolant and re work flow on the deck 5/6 heads can fit on older blocks but not that great of a head less you have put the 7/16 studs on them so you can run the old type ajustable rocker arms you can not run the old mark 4 heads on the gm 5/6 mark blocks there not much around the deck on the older head to hold the head gasket seal were it gets thin is the lifter valley side of the deck