How would you define 'vigorously'?
Would a stock '72 351CJ with Holley 600 that's probably on the original valves be in danger of losing it's valve heads during road use (i.e. rarely above 5000rpm for more than a few seconds).
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.