Hello, new guy here with a question, I am building a 68 Thunderbolt from boxes of parts and it did not include the original pistons. I am trying to find out the weight of one original standard bore piston
The std pistons are lighter than most, and early ones are different again. Sorry I don't have the weight of a std piston, but what looks like a + .020" JCC 397g a + .030" Hepolite 420g .040" 425g both latter style 9-1. MC 10-1 402g all with pins. Different brands can be different weights. Generally with cast pistons, the bigger the heavier because they are thicker in the skirt. Forged B44 80mm are around 372g with pin, 79.5mm Omega cast are about the same. T140 are 340g with pin.
I didn't find the '67 L pistons, but I did find a pair of OE pistons from a '65 Lightning Rocket. I can't say for sure if they would have used the same pistons in '66, but it would seem likely. They appear to be 9:1 CR. I'll include the markings on the pistons if that helps anyone.
Piston 1: On the crown, 68-892 BSA/T, and 46/4/67 L. Next to the pin, 68-743 and AM, other side, LO-EX and L66. Weight without rings and gudgeon pin is 9.9 oz or 281 grams.
Piston 2: On the crown, 68-892 BSA/T, and 46/9/67 H. Next to the pin, 68-743 and AM, other side, LO-EX and M66. Weight without rings and gudgeon pin is 10.1 oz, or 286 grams.