[MidOHasp]

Wilf,

My engine guy ran about 20-25 minutes of varied light to medium loads to simulate driving around town then ran it straight to 6K, full dyno pull, no questions asked.

His explanation:

Things basically get broken in immediately. If there is a microscopic "high point" on a cylinder wall or on a main journal bearing, it will get knocked down and smoothed out first time the starter cranks over. With a solid flat-tappet cam, I guess then you do need to really break it in for a while to seat the lifters or something like that. (OK that last sentence was my take, not his words. If he said that, I'd be out there disconnecting the dyno immediately).

Long story short, if you have a hydraulic roller cam, the motor requires no break-in. You could run it at 2-3K RPM for 10,000 miles of break-in and if it was meant to blow apart at 6250, then it still will. Or if your engine wasn't meant to blow apart at all, you could run it up to whatever RPM it was designed for immediately.

This guy explained "his" warmup as basically a diagnostic check. Check pressures, vacuum, check for leaks (there were a couple), set initial timing, etc... Once that's set, it's time to rock and roll.