There is quite an interesting article that analyses cam timing vs. compression, at the following url:
http://victorylibrary.com/mopar/cam-tech-c.htmYou can download an excel spreadsheet that estimates cylinder pressure. With my 541ci RB, using that spreadsheet and associated formula's, my measured cranking compression is actually within a few PSI of the predicted value.
For a given engine, the key determining factor to cranking compression is static compression and the intake valve closing point ABDC. You need to use the advertised value (not the value at 50'), as compression cannot start until the valve is fully closed.
Ive taken the liberty of inputing some values into the spreadsheet for your 340.
Based on the calculations, if all 3 cams are installed on the same ICL then:
XE268 calculated to be 154psi
XE262 calculated to be 158psi.
Remember, this is only a theoretical calculation, and your results may vary, as there are numerous real world factors that are not taken into account. I would be interested to see how well the spreadsheet calculations match up to other users known engine parameters vs. predicted values.
