Helping a friend with an engine which we believe is 1960 650cc head's an barrels on a 1957 600cc bottom end an crank cases done in the past by someone most likely after an engine failure. The problem is the pushrods are to short an so due to the mixture of parts i was wondering if AJS had changed the Pushrod length at some time or for different capacity of engine (as i know they a changed the stroke). ?? The manual gives no mention of length of pushrods as far as i can see (i may have missed it or it may be in a different manual to the one i have seen) Also if it comes to it i could make him some longer pushrods by reusing his ends an turning up new aluminium parts but what grade/specification of material should be used to do this?.