Performance Motor Break-In Procedure?

[Gaz64]

Every engine I've assembled is considered run in within the first day.

Don't baby it, don't free rev it, and don't over rev it.

An engine of that size with the right parts should see wide open throttle blasts to 5000 easy.

Generally speaking, the order would be top gear 30mph, accelerate to 50 mph WOT, coast to 30mph. Repeat 10 times.

What carbs and camshaft do you have?

[blykins]

Is it a flat tappet camshaft? That's the first question I would have and even if it's been run in on a stand, I'd still take it easy for a bit.

On the dyno, this is how we break them in.

Fire them up, set the carb and the timing. Put a very light load on them and run them for about 30 minutes. After that, I put a short pull on them to about 5000. Then I run the valves, do an inspection, etc. Then it's on like Donkey Kong.

In the car, you will want to follow pretty much the same procedure. I would drive it a lot on an open road, getting up to speed, then letting the engine brake the car back down to a lower speed. Let it climb back up and do it again. Keep an eye on the gauges and remember that when engines heat up, valve lash/lifter preload changes, so keep your ears open too.