where does the block need to be clearenced to fit a 3.750 stroke crank and a 5.7 rod? is there also a need to clearance the oil pan rails?

 

Although every block is not cast the same.. here are some general ideas of where you need to grind:

1. Bottom of cylinder wall near the camshaft.
2. Oil pan rail.
3. Back of the block in the corner... near the thrust bearing (because the crank throw will usually hit it) near cyl #8 I beleive.
4. There are notches near the oil pan rail that GM already clearanced out from the factory, you will need to clearance those more.
5. Oil pan (usually)
6. I also had to clearance my oil pump (because of the crank throw).

I did all the grinding with my father, we used a Dremel tool with grinding bits. Just take your time and you'll be all set

 

More than likely a couple of rod bolts will have to be ground on to clear the camshaft.

Just put the crank in, spin it over, and start putting rods/pistons on one at a time. Each time, spin it over, see where it hits, and do the clearancing.

BTW: Whats the clearance? 0.100" for heat expansion right?