pablorg wrote
82Waggy: Thanks a lot for your advice! I think I will be rebuilding my 360 in about 6 months so I will definitely take a look at the Engles 5052H and 5054H....
If you don't mind, last question: what is the difference between these two Engle cams?
Basically a difference in the rpm range at which peak power is produced, the later being a bit higher up.
If you have everything else to support the longer duration, like higher CR, proper induction, free flow exhaust, big gears to let it rev up to optimum rpm, etc, then the longer duration can result in more peak power without much loss in bottom end. If you don't have everything else to support the longer duration they can often lead to a loss in overall power and usually lose torque, vacuum, and throttle response at the bottom end due to a later intake valve closing point and more overlap - so be careful about your choice. If you don't run up to the higher rpm ranges or are lacking any of the supporting features, stick with the shorter duration cams.
Duration in and of itself only shifts the point at which peak rpm is produced (about 500rpm higher for each 10degree increase in total duration) with little increase if any on the maximum torque value produced. When in doubt, go with shorter duration.
PS: On the flip side, if you are running relatively high compression, closing the intake valve too early can result in excessive cylinder pressure ("dynamic", or "running" compression ratio) that may lead to detonation (ping), especially under load such as when towing or grunting up a hill - so you need to look at the whole package.
I use a couple of calculators to estimate dynamic compression ratio and then choose a cam with appropriate specs - after running I may make changes if I want to shift from the baseline this process establishes.
