Tony,
OK, now we know that your 100 percent that the engine was bored correctly. So this leads to another thought, just today in the shop we had a BIG piston.
First I got a question for you. What did the piston skirt look like on the opposite side of the piston on the top?
The reason I am asking, I'm not a ("quote")engine machinist, but a regular repair machinist. I have seen many many STUPID things done on engines and everything else that comes along in the past almost 20 years. BUT, still machine work is machine work, the two go hand in hand and specs. are specs. .0001" on and engine is still .0001" on a bearing area.
ANYHOW, One of our other machinist was working on a VERY large piston about 10 inch in diameter from an engine for a natural gas pipe line distributing station. (regular engine machine shops don't work on these big beast) Anyhow, this piston started locking up and showing a mark on the bottom (skirt) and then another marked area on the top opposite side of the skirt. After we (not myself) took the piston and measured it all up, everything was in their specs. BUT, We found out that the piston itself wrist pin bore was bore at an angle about .015" from parallel from the top, bottom and side of the piston. The bores were both straight with one another, just bored at an angle to the piston. In return it was causing it to "cock" in the cylinder bore.
This gas companies maintenance crews know when something is not going together correct. From what I gathered as they were installing the piston etc. Pistons fit in the bore great, just when the connecting rod was installed on the piston and on the crank shaft everything was getting extremely tight and could not rolled it over, but they could not definatly locate the cause of the problem.
That's when it came to our shop and we discovered this small problem. They found out that 2 of the 6 pistons wrist pin bores were bore this way. Probably just from the factory's setup fixture.
Back to this engine, I don't know all the particulars of the engine (Stroke or HP), but I know the valves are HUGH. I just reground the valve seat faces, here a couple weeks ago. 4 inches in diameter on the vale itself and a overall length of 20 inches and the stem is about 1-1/8 in diameter.
I would just love to have an old burnt valve for a conservation piece and/or a door stop, LOL!
FOOD for Thought, THIS IS ONE OF THEIR SMALLER ENGINES!
This is JUST a thought, after seeing this one today. I know you said the piston were new or close to new and that you have cheked them, but have you thought of a bad wrist pin bore? Honestly speaking, it's probably one thing I don't check on building a new engine.
My guess is that it's probably somthing real simple, more than a mis-aligned wrist pin bore, like here, but ya never know.
Just had to share this story with you.
John
