Engine break in opinions

[2mAn]

bumping this because it has good info, but I have one additional question

After the initial ~300miles of varying RPM & load, is it safe to drive 1000miles on the freeway. Mostly cruising, but there will be plenty of spots where a LOT of throttle will be applied

[TurboJake]

even 300 miles is too long. At 1st startup and warmup, drive it like you stole it (Especially hard pulls and lots of engine braking). After 50 miles, life is normal again.

So, to answer your question. Yes. Everything internally has been set for over 250 miles already.

[Cletonius]

We always broke them in on a dyno when we built Ford 302's. High cylinder pressures are required for a good ring seal.

Break in the cam and flog it like a red headed stepchild.

[Stanley Rockafella]

drive it like you stole in the 1st 20 miles, if not you will have a dog. And might not get the rings too seat well.

+1

[Dj Buttchug]

New Motor

First 300 miles on regular organic oil, vary RPM and Load.

After 300 miles, change to synthetic, and beat the shit out of it.

pretty much this.

[Thizzelle]

all these opinions seem like just fire it up and drive it normal, at least for me. Change oil a bit after

[slammin.e28]

This thread makes me want to build an engine just to have fun breaking it in.