1970 Dodge Dart 318 upgrades

nm9stheham said

I have been musing on this and can't quite figure this out. But I'm not sure I know the right answer so thought I should throw this out for further comment:

• Seems like more lift in a shorter number of degrees would be higher speed ramps, and put more pressure on the valvetrain during opening...? (And I am only looking at the advertised vs .050" durations, as I don't have other numbers like .200" durations.)
• Now, if the opening lift occurs sooner, and the closing ramp starts later, then maybe going 'over-the-nose' will be gentler, and less need for heavy springs to fight float?
• Then on the closing, the deceleration at the end of the ramp would be harsher and higher pressures again, so it seems.

I am just trying to understand how this higher lift, short duration cam would be as easy as a low ramp, and the only place I can see is 'over-the-nose'

Click to expand...

Looks like you got it right to me.
The need for valve springs to exacting cam specs should have been handled by the grinder. However a heavier spring, needed or not, not only helps control the valve better but also for more rpm.

Going deeper than this becomes a scientific chat.
You can do better by reading up from the original cam greats. Start with Mr. Crane and finish up with Harold Brookshire.

If you get what there talking about, your in awesome shape. I just don’t think I can regurgitate what they say simply. It’s just a bit complex for me to break down. They do a good job in explaining things anyway.