So John, is that Jerry's usual shop? I'd had thought being that close to Nashville and all those guitar amplifiers some of that electricity would filter out to the countryside. I mean we even have electricity here and it's an hour's drive to the nearest BPA dam. Granted it took a shooting war to get BPA power up the valley.
Along about 1968, I got a part for my 66 Pontiac machined by an old fellow in Leominster, MA. He was 90 then and told me his father had built the machine shop, starting by hand-building a lathe for which he had the headstock cast in Boston and hand built the rest. From that he used the lathe to make the rest of the tools, all driven from above by flat leather belts running on pulleys of various sizes. It had been powered by wood-fired steam and eventually coal and after WWI they converted to oil. When I saw it the power was from a huge electric motor that you could see into and watch the brushes arcing. It was like the history of the American industrial revolution in one shop.
Today, a lifetime later, I came in for lunch and it's too hot to go back to work so I'll write up the latest on my 261 overhaul. It got to a hundred yesterday and today is supposed to be 106. My machinist is only working till 3PM these days because he's got no air conditioning. Neither do I. So yesterday morning I drove to the neighboring town to collect my knurled pistons and my rods. My pistons now have a nice Perfect Circle logo knurled into the skirts.
I had checked the con-rod bores and could tell they were round to 0.0005 but with the heat I couldn't tell how big they were. My Jo-block is as hot as everything else -- hardly room temperature. Anyhow the machinist keeps his jo-blocks in the fridge and knows what the mic should say on a refrigerated Jo-block. A Jo-block is a piece of metal of known size used to calibrate micrometers and such. Anyhow, he had checked the rods and said they were right on and still straight and he didn't charge me for that. The piston knurling was $10 each and I though that was reasonable.
He was of the opinion that knurled pistons should be fitted tighter than I ever have, basically filed down so you can just get them in the bore and they'll seat themselves. That scares me. These are solid skirt pistons destined for heavy-duty truck work and I've replaced a few Cummins sleeves and pistons when the drivers weren't watching the pyrometer and stuck them. Those are the same guys that pop head bolts. Sometimes you can head that problem off because you can see antifreeze stains on the block from the heads bouncing up and down. Write a little note and put it in their box with their dispatch so they know you're watching. But I digress...
I compromised and set the pistons to a stiff pull on a 0.002 feeler. Hopefully they won't slap and they won't stick. Oil catches in the knurl so oil control is better and you can fit them tighter. He did a good job. I told him what bore sizes I had and numbered the pistons. In the end it only took a couple whacks with a file to set the clearance. That was yesterday.
