While reassembling the engine I noticed very light stampings in the block next to each stud on the exhaust side of the engine. Either a “G” or a “H”. Does anyone know what these are for? I asked the machine shop and they said it was not theirs.
Probably the measured bore size used to select the piston size/grade to fit. Available in grades F-K for example, for the 3.8 E-Type engine.
-David
Thanks for the suggestion. Very logical. Since the machine shop I used did not stamp it must have been from the previous which was I believe around about 1970’s.
Its from the factory. There were five sizes of pistons lettered F, G, H, J and K, for bores that were measured in diameter ranges of .0004" increments. See page B38 in the Service Manual.
…and the fact that they are still there means your block only needed a very light skim…my letters were removed when my block was shaved.
Thank you gentlemen. I see on page B38 you are correct and that the size difference between letters was .0003. I am surprised that the original bore/piston would not be accurate to within a closer tolerance and that all pistons would be of one size. Also makes me curious if the new piston supplier for my overhaul (Mahle) went through the same careful consideration.