They get pretty low at 60 LOL

Ok it was a bad idea to put those on engines--they were very susceptible
to failure if not from miles just heat and age--I am thinking it was done to quite noise--Noise I have never heard but anyway

The COOL thing is when you read about one of the greatest engine innovators that ever lived Grump Jenkins Jenkins Competition--Sox's worst nightmare and a guy that could wring more HP and performance out of a stock block deal than almost anyone--well The small block Chevy Pro Stock engines he ruled the earth with had that $12 plastic teeth timing set on his $$$$$$$$ Pro Stocker with tunnel ram turning over 8000 RPM and the reason was---wait for it--- He said it acted like then banned belt drive --actually absorbing ( or not transmitting) bad harmonics between valve train and the rest of the engine That is EXACTLY what a belt drive does--you can gain valve train stability and thus gain HP by separating the valve train from the rest with a belt drive--they are used for no other reason by knowing builders when legal Otherwise there is just no reason to run one You can observe 318 SS combos where they run one and that is why---

But----they are engine "fuses" or as I believe Pieces of JUNK