Hello all i have an 85 truck slant six. I didnt know anything about this engine so i tore it down to inspect. I discovered the cylinders still show the cross-hatch, no unusual wear. Very little if any ring ridge. Rod bearings look excellent, I havent inspected the crank bearings yet. The problems i have found is that the cam lobes on number 6 are badly pitted, no rust. The rest of the cam looks great. Pitting is so deep on 6 that im not going to use the cam. The next is the number 6 cylinder and piston. The number 6 cylinder is scuffed vertically in several places, not very deep, just marks on the cylinder walls. The sides of the number 6 piston is scuffed as you can see from the pictures and theres a small section where the piston is missing some material above the top ring. The top of the piston looks normal.
When i first started tearing down the engine i pulled the head off and was looking in the cylinders to see if the pistons were centered in the bores. All of the pistons were nicely centered and had approximately the same distance between the piston and the cylinder, except for number 6 of course. Number 6 had no gap between the piston and the cylinder on the side that was missing the material and a larger than normal gap on the opposite side.
I plan on putting in a new or used cam and a used piston/rod assembly and run the engine. But what happened to the cam and number 6 piston?
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https://postimage.me/image/1000003998.SN6D6