Yes...valve adjustment has to be done every now and then. Which is why it is an emissions thing. I would hope you are checking things over every 10-15k miles in your 450rwhp, 520fwhp, 5.7L, 91 hp/liter engine!

In the 60s and 70s, no real high performance engine came with hydraulic lifters. My Supra TT doesn't have them either. And I believe people take them out of DOHC modular Fords also.

 

Thanks for posting the article. Excellant read. Vizard states if you do what he says you can run a 1/2 point higher than what the chart says. Also he does not differentiate between aluminum and iron heads. Thought that was odd.

 

He does mention aluminum heads halfway through.

 

So ok.. Detonation is caused by a lot of things right? To high of a DCR with not enough octane at a high temp is one of them right. Well, what would be better for bottom end torque and shifting at say 6200-6300rpm:

Motor details:
348ci
-2cc forged pistons
Stock heads
Z06 manifolds

Lower DCR (8.0ish) running 91 octane at 180* with higher timing

or

Higher DCR (8.5ish) running 91 octane at 175* with less timing

 

I can tell you that 9.3 DCR knocks pretty bad on pump gas. Even with the .040 gasket. Knock is a killer on race engines.

 

For me the most DCR I can run with the coolest temps and NOT dialing back timing is a winner.

Bret