Engine break in without a tachometer

I'm far from a forum guru, I've already been told so, but I still know what I'm doing LOL
I've never lost a cam or shredded metal by not using a tach or a timing light. I break them in on the floor of a garage with open headers running between 2 and 3000 rpms for up to 40 minutes sometimes. the neighbors love me ! lol

Well sure you can do it without one. BUT he's never done this before. Does he know what 2500 RPM sounds like? I don't know. So my best advice is to hook the tach up. I wouldn't let three wires stop me. JMO.