bore clearance query

[jellywrestler]

hey folks
what thoughts are out there on bore size/clearance for the diecast shadow pistons?
E7/7AS/D 7.3:1 Piston Diecast

 

[chankly bore]

There are a few different opinions around.On my original Comet I run .005" bottom skirt clearance, 35 deg. magneto advance and have had no problems and negligible oil consumption.My newest Comet nipped up an original Specialloid so I have gone to diecast with .006" clearance.There is a theory in Australia at the moment that premium fuel (98 octane) burns cooler and is less likely to cause seizures.The evidence so far is only anecdotal; any comments from the ethersphere? I add that my bores are round and the muffs fit properly and are true to the crankcase mouth faces.

 

[ogrilp400]

Club low expansion pistons can be run at .003" However the bore must be true and the muffs the correct interference on the liner.

 

[davidd]

Chankly's advice sounds good. With a twin you may choose the tight side of the tolerance, but with a Comet it seems best to choose the loose side. When pressing a Comet you have all that heat working one piston very hard.

David