[tbucketnut]

Well I find out not all 305 blocks are created equal. This bit of info might be useful for others and should be a sticky. I thought the only difference in the 305C engine were beefier rods but I find my main bearings do not fit the main webs and cabs. It turns out my 305C replacement engine I found was casted in 1974 and the main caps and webs are different. It takes a bigger main bearing. So I now have a fully machined .020/.020 crank and main and rod bearings I cant use.

When I checked the casting date it had a year 4 which I assumed "64" but it is indeed "74" based on block casting. I got lucky and found main bearings only in .010 undersize so I had to machine another crank. Note I belive the last two years of production 1973-74 305 engines have the bigger mains. Why did they change for two years and then discontinue the engine? Things that make you go Hmmm.