Replacement 68 340 four speed cams

krazykuda said
It depends on the manufacturer and how they spec their cams... Every manufacturer has "their" way of doing it... Some do it at just after .000", some at .001", and some at .006"...

That's why sometimes it's better to compare the @.050" numbers as to the advertised duration numbers, it eliminates the 'room for interpretation' out of the different ways the different manufacturers spec their cams...

One of the reasons that I made my spreadsheets so I could get a better feel for the numbers and try to compare them more accurately...

Plus, by comparing the advertised duration to the @.050" duration, you can get a feel for the ramp speed that they use to open/close the valve...

Slower ramp speeds set the valve down more gently... Faster ramp speeds get the valve open faster so it flows more for the given duration, but sets the valve down quicker/harder... Setting the valve down too hard may slam the valve down to where it increases wear/beats up the seat...

You have to balance them to pick one that best fits your needs...