I'm not the expert here which is why I was hoping someone who was could chime in. However, I'm pretty sure that a 1cc decrease in chamber size does not equal .1 drop in cr. That would be too easy.

Ive seen stock chamber sizes ranging between 70 and 74 listed for 317s. And not just on forums either. I mean in different articles and reference books I was able to google. Do they just vary that much from the factory or is it different for different years maybe. Thats whats making this so confusing.

 

I've been searching around and everyone with a LQ4 block and 243 heads are at 10.5:1 10.6:1.

 

I agree, thats what everyone is claiming, I just cant get the math to work. Im probably doing something wrong in my calculations but I cant figure out what. Although my numbers are consistent with SynergyV8's replies. He makes his living doing this so I naturally consider him to be credible.

SynergyV8, are you out there? What are we missing?