[BriTtO]

What is the best run in procedure for a built motor?

I just had my block rebuilt with forged internals and was wondering what you guys are doing to run in your motors properly.

I did a few searches but couldn't find much info.

[RemlapaN]

Mine was broken in by the builder by immediately taking the car up to 12psi after the initial startup / lookover to make sure the rings seated well.

After that, the only rules he gave me were "I don't care what you do you as long as you stay under 5000rpm and under 10psi until 1000 miles, but dont baby it"

[corey]

Originally Posted by RemlapaN

"I don't care what you do you as long as you stay under 5000rpm and under 10psi until 1000 miles, but dont baby it"

If anyone is interested in reading something contridictary to nearly everything people have ever read/been told, check out Jeff from Import Builders.

[jays05]

Idle at 2000rpm for 20-30 minutes immediately, if you've replaced the cams.

[BriTtO]

I spun a rod bearing, getting block machined and getting forged rods and pistons etc.
Ive never had to run in a new motor before, so Im gathering opinions.
Thanks for all the info so far.

[gabedude]

Originally Posted by corey

If anyone is interested in reading something contridictary to nearly everything people have ever read/been told, check out Jeff from Import Builders.

Even a fast breakin on a stock motor can crack ringlands. Of course the PWC is probably more off on a stock motor than on a very well built one. The reason for breakin is that most people (unless you take it to a reputable shop) will not get the PWC exactly correct or the ring gap, hone, etc. Having a couple maps with correct fueling (gosh he harps about a WBO2 like 8 times) dialed in is the first part. That is your breakin map.