What's the minimum clearance I can have between the block and the crank counterweights?
Reason I'm asking is because I just got my new Scat crank home and the rear counterweight hit the side of the block where the oil filter sits. I only had to grind the block down about 1/16" to allow the crank to spin freely. I've got just over .02" of clearance between the counterweight and the block. I can't go but probably another 1/8" before I get too close to the oil pan bolt hole.

 

I try to keep it at least .025" and I've never had anything collide with anything else at that clearance in a stroker bottom end. You're real close.

 

I don't really have a good way to measure it right now, no feeler gauges in my arsenal or anything. I just used a cardboard cereal box top. The crank was sliding against it, but there was no pull or anything. I measured three times and got .020, .022, and .020 again. I just used this method to get a general idea where I was at.
So anything greater than .025" and I should be okay?

 

I found a piece of steel stock that measures .045". It slides between the weight and block just fine except at one point where it hits and slightly catches. I'll grind that down a little more and test it again.

 

Get a plastigage string and put it in the groove and swing the crank till it crushes it.

That will give you an accurate-ish number for about $0.50

 

I thought about doing that, but I figured the weight would break the plastigage rather than squish it and I wouldn't be able to get a reading.
It's cool though, I got it ground down to where I could fit two of the .045" pieces of bar in there with a little wiggle room. I've got just over .09" of clearance.

 

i've used music wire crimped ina piece of steel tube for a gage. can't remember the diameter right now but it was close to .050, it was 2nd or 3rd string from a guitar.

 

The machine shop that built my shortblock told me to use 2 plastic wire ties together to check stroker crank clearance. Watch the big end of the rod & cam lobe clearance as well. The shop reccomended .050" clearance on the rotating assembly.