I am thinking of using a 4.25 over a 4.15 stroke crank.
How much clearancing of the block is needed,any pictures?

If the 4.25 stroke crank has 2.2 BBC rod journal dia., it may need no clearance work at all. If using a internal oil pick-up you will probably have to do a little work in block where it screws in.

I have the 4.25 crank in my 57 truck. As stated above, I only had to do a little grinding where the oil pickup screwed into the block.

Would a 4.15" stroke using 2.20" rod journals likely be a "no grind" installation?

I agree that with steel rods, the 4.25" stroke with 2.2 Chevy journals only needs a touch on the oil pickup boss. Attached pic is all I needed. You should also check for clearance at the bottom of each cylinder to the rod bolts. But they may clear without any grinding at that location.

I've built a few of those 505 inch motors over the years. I think it is probably the easiest and best BB stroker combo going. 4.250 crank with 2.200 rod journals then buy either 6.800 or 7.100 long BB Chevy rods and matching pistons. Very little bottom end clearancing needed. Maybe a slight touch on the oil pickup boss and maybe a slight notch on the bottom of the cylinder walls depending on how big the connecting rods are. If you use a high quality I beam rod you usually don't need any clearancing. The cheaper H beam rods are a little bulkier and might require a few minutes of grinding.

I'm building one right now. Eagle crank, chevy rod. I put the crank in and the rods cleared fine so I went on with the build but noticed after I put in four pistons the counter weights are very close in a couple spots. I searched on here and found a post from BG a while back where he said some blocks need clearance for the counterweights and some don't. I have to pull mine apart, clearance it, clean it and try it again.

I put together a 4.25" stroke 440 recently. I clearanced a fair bit on the oil pickup boss. However, it would of been WAY WAY less possibly none but I only had 1 rod and piston combo back from the machine shop with the block to do the clearance checking, I was way more worried about getting the piston the right way and had the rod in the wrong way for that throw.

Brad,
I never did that combo, but from the other combos (4.25/2.2 and 4.15/2.375) I would think there would be no clearancing for steel rods.

A 4.15 with 2.20 journals should clear just fine. Not a lot of those cranks around, for some reason the 4.15 cranks usually came with the larger Mopar journals.

I do have a 4.15 with 2.20 crank in my World block with Oliver I beam rods. The Oliver rods are very compact so there is a ton of clearance.

Scat offered an RB 4.15" x 2.20" that has since been replaced by a 4.25" version, but I know where one of the original 4.15" cranks is. Molnar currently lists an RB 4.15" x 2.20", too, and it's a 6-bolt (no need to change flexplate, either).

At least one (possibly both) of those companies has 6.76" x 2.20" h-beam rods, and there are plenty of piston choices for that stroke combination w/o having to go custom.

On paper that seemed like a pretty straight forward way to build a machined RB 4.375" bore block into a 499. Not that I NEED another 48 cubes, and already have all the parts on hand (Eagle crank, K1 rods, bearings, CP pistons) for the 451 it was intended to be.

EDIT: My apology to the OP for semi-high-jacking this thread.

Took off around .060 of iron off the the oil pick up boss. Now I have around .080 clearance between the 2.20 Chevy rod and the block

I ha to clear some on the pic up tube to !