well this was the problem I had... Spun the #4 Rod Bearing, its hard to tell from the pic but there was an overall .030 missing from the crank( making it garbage )..
The Rod was No better also making it trash... Not a great pic, but you'll see the damage... The rust is from me letting the rod get wet after removal...
This is the section of the piston that was kissing the head for 120 Soft miles..
In the end I actually had the Engine replaced with a Low Mileage JY unit.... Been 1 year and it still runs good.. But I have noticed it has a slight thud thud thud when the oil is changed signifying to me that it has a bit more rod clearance than I'd like... It only does this when the oil is changed, You will never hear it again untill the next oil change..
The engine that spun the number 4 Rod bearing was tossed to the melt down pile.. I did get the heads and related items... The Block was scrapped...