06-04-2020, 01:32 PM
I wonder if this helps you John?
BHB were at least around until 1956, their piston drawings are available from the archive, some show 'without' oil holes and this one shows 'with'. I'd venture that as long as a bit of metal is left to support the gudgeon pin drilling two wee holes is unlikely* (*all the usual caveats apply!) to cause you a problem. On the other hand it would appear they made plenty of pistons without them.
BHB were at least around until 1956, their piston drawings are available from the archive, some show 'without' oil holes and this one shows 'with'. I'd venture that as long as a bit of metal is left to support the gudgeon pin drilling two wee holes is unlikely* (*all the usual caveats apply!) to cause you a problem. On the other hand it would appear they made plenty of pistons without them.