Can being to conservitive on ignition timing raise egt's and cylinder pressures enough to lift the head and blow out a headgasket.

 

Retarded timing can raise egt's but shouldn't cause head gasket problems.Make sure your base timing is correct.

 

Retarding timing to an extreme degree will start to raise EGT's, but never peak cylinder pressures. 'Perfect timing' will put peak pressure at 14* past TDC. Less timing will put it further past TDC, meaning a lower overall pressure in the cylinders.