Valvetrain Geometry
Well, dang near every V8 Mopar made has bad valve train geometry and they didn't break. But neither did they push the boundaries regarding valve train.
As long as the rpm is near stock levels, the lobes are soft and the spring loads are minimal.
Once you start getting away from anything stick, like an aftermarket rocker and then increase the rpm and spring loads to go with it you will see parts damage and failures.
I have a 471 on the dyno that didn’t have the correct valve springs on it.
When I went to change the springs it was already beating the **** out of the locks and retainers. And that was at 6100 rpm. It was so pissed off I wouldn’t dare try and pull through it.
The customer did not really understand what the issue was, so he was here this time to see it first hand.
We used a spring that was bigger on the OD and had a larger wire diameter.
I think we went down on seat pressure by 10 pounds and up 10 over the nose.
Where is was struggling at 5800ish and was miserable at 6100, now it will zip right up to 6900.
Fortunately, his geometry was very close and he paid for overkill Pushrods’s or it would have killed some parts.
When you do this every day you see the effects of **** geometry.
I just got off the phone with Mike. We discussed some of this stuff, including the fallacy that the 1.5 ratio is perfect for the small block. It’s not.
If it was, then why make the magnum with 1.6 rockers? They could have left well enough alone but they didn’t.
Most of the time when an engine doesn’t make more power with a higher rocker ratio it is geometry related.
You can run the same lobe on a 1.5 Chrysler and a 1.7 big block Chevy and the Chevy doesn’t go out of control.
In most cases a higher ratio rocker will make more power unless there are issues somewhere else.