Rich Carb

Yeah, the early 340's were rated at 10.4:1, but that's a factory rating and I'm betting that if one were actually cc'd and measured right out of the factory (no additional machine work, heads, etc), it would be closer to 10:1.

That's just my opinion and I've never had the chance to break down an unmolested 340, but every other engine i've broke down and measured was around .3 to .4 less than the factory measured ratio.