What caused this camshaft wear pattern

[70rrclone]

From day one this valvetrain has seemed unhappy.

 

[PRHeads]

I don’t think you ever really had enough spring to control it.

 

[PRHeads]

Your new plan of the SR should be a nice improvement

 

[autoxcuda]

+/- .010” is great.

The TF springs are PAC-1903……391lb/in, listed as 110@1.900 and 130@1.850.
391x .020 = 7.8
130 - 7.8 = 122.2
391 x .580” = 226.7
226.7 + 122.2 = 348.9

Personally, I don’t feel like that’s really enough spring to maintain control at higher rpm(with that cam & 1.6RR, with the fairly heavy TF intake valves).
But at the same time, the fast rate profile can really tax the Hyd part of the lifter at high rpm.
I kinda feel that situation is the worst of both worlds.

To take the Hyd part of the lifter out of the equation, I’d want more seat and open force.
Something like 140-150 seat/360-375 open……. But Hyd lifters don’t always play well like that.

It’s a bit of a catch 22.
The valvetrain needs what it needs for force to maintain control in the upper rpm…….. but that’s often more than the Hyd portion of the lifters cam effectively deal with.

All that said, It’s not all that likely that more spring force would have made that cam live.
So you’d still be where you are now.

So with a cam of that size/agressiveness and net lift, is it safest to go mechanical ?

 

[PRHeads]

Imo, absolutely.

We fought with Hyd lifters in my buddies stocker for a pretty long time. Spring pressure wasn’t at all effective in upping the rpm ceiling.
At the time it wasn’t legal, but we were searching for the root cause of the problem, so we tried some solid lifters on the Hyd cheater cam.
Poof!! Problem solved.
Got some Schubeks for it after that, which were essentially Slightly squishy solids(severely limited travel Hyd), never looked back.

This happened a bit after we worked our way thru my friends stocker cam woes:
Mild-Mannered 440 Mauler Mayhem - Part 5, The Dyno Test