Crankshaft Clearance Problem

This is a first for me and want the correct fix to the problem. Mocking up the hemi motor with a 4.15 stroke Ohio Crankshaft and the large diameter throw on the back of the #2 and #6 rod journal is hitting the block at the cam webbing. What the problem is the throw of the crank has no radius on the OD which is causing the rubbing on #2 and actual hitting on #6. What is best to fix for the problem? Grind block for clearance which would be a pain, hand grind a radius on the crank throw, or take it to a shop and have lathe cut the radius for clearance? The assembly has not been balanced yet. The hemi block is an original casting.

On my R-3 block the crank hit webbing near one of the
mains... I ground the block for clearance... I just
used a 1/4 die grinder... doing it this way I could
put any crank in it without having to rework each crank

tough to say without seeing how close. Having not balanced yet, you could grind down crank for clearance, but there are a lot of variables. If your piston/rods are heavy, you won't want to cut crank. If you have lightweight parts you'll need to lighten crank anyway. I would strongly suggest you mock up entire rotating assembly, and add cam and timing chain then check for clearance before balancing. Mallory metal is not cheap

First off what is the bob weight of the rotating assembly ? If the bobweight is 2450 or above grind the block. If it's less you can cut the counter weights. I usually cut those .150 and still have enough to drill for balancing. I think most of the target bob weight is 2500. Give Scott at Ohio Crank a call and ask very nice people and balance a lot of their on cranks. Hope this helps.

Whatever is minimum clearance required in this area? The #2 just touches and #6 his by about .010-.015. So minimum grinding or chamfering would be required.

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Whatever is minimum clearance required in this area? The #2 just touches and #6 his by about .010-.015. So minimum grinding or chamfering would be required.

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I had the same clearance problem as MrP. I clearance it at .100 to be safe.