compression ratio???
 

hello all

im building a new motor for the boat,its a 350 changeing the pistons for more compression but was told not to go over 9.2 to 1 or the motor will burn itself up,
im usen dart 64 cc heads.
any sugg, on compression and cams,to keep the cost down thinkn of replaceing piston with cast,what do you all think ??? thats whats in it now.
any and all suggestions are needed and welcome,this is also a
merc stern drive


thanks stan

Forged pistons are well worth the money and aren't a great deal more than cast. Hypereutectic pistons are available and are a cost effective alternative.

A good rule of thumb for compression ratio and pump gas in marine engines is 9:1 with iron heads, and 10:1 with aluminum. There are things that can be done to allow more compression, but these compression numbers will generally be safe. These are for 93 octane pump gas.;)