I have not seen any discussion concerning offset dowel pins and cylinder head alignment. This topic is mentioned in the Chevrolet Inline Six Cylinder Power Manual, 2nd Edition, pp 113, by Glen Rarick of Bow Tie Speed and Reproduction. His telephone number is now longer in service.
What size are the dowel pins, and where are offset pins available? Rarick states offsets of 0.030" to 0.090". Can you completely align the combustion chambers with the cylinder bores? Will the current overhang of the combustion chamber beyond the cylinder bore be alleviated? How much power is gained?
