rebuilt engine break in periode

[miller]

so all new cars say your suppose to drive your new car without going over a certain rpm, or pull anything, or in general abuse the car, for a certain number of miles

what is the rule of thumb for rebuilt motors, it seems that everyone would, after the long rebuilding process, want to take it out and see what it would do out of the box, but how long should you wait to make sure everything sets properly?

[RD]

start it up, break in the cam around 2000 rpm.  make sure you have oil pressure....


THEN BEAT THE HELL OUT OF IT!!! lol

I have heard of guys breaking in their engines at the strip if that tells you something.  I believe in the:

flogging it every once and a while and keep varying the RPM's up to 500 miles.

[Chryco Psycho]

it depends how tight the engine was built , I generally give the engine 500 easy miles just to let stuff seat in , then give her all she has

[terrible one]

I've heard many things, from taking it easy to going all out, or "driving it like you'll be driving it." However, generally I've heard that you need to break the cam in at 2,000 RPM for a good bit, change the oil, then go at it. Still, I'd sure like to hear other's opinions as I'll be breaking in two pretty soon. . .

[firefighter3931]

The breakin period depends a lot on the type of rings that were used : Moly rings seat up faster than Cast rings. 

Generally i like to break them in on a dyno but that isn't allways feasable or cost effective. If it's a mild street type build i would give it 300-500 miles of easy driving with the occasional blast up to 4500 rpm....then let it rip ! 


Ron

[375instroke]

After cam break-in, a few half throttle 1/4 mile-ish passes, then a few full throttle 1/4 mile-ish passes, and drive it like you stole it.  Combustion pressure pushes the rings against the cylinder walls from behind and is what "seats" the rings.  Baby the motor, and the crosshatch gets polished before the rings seat, and you're screwed.  How are race motors broken in?  They need ring seal to make power, and they don't drive them for 500 miles babying them before they race.

[RD]

After cam break-in, a few half throttle 1/4 mile-ish passes, then a few full throttle 1/4 mile-ish passes, and drive it like you stole it.  Combustion pressure pushes the rings against the cylinder walls from behind and is what "seats" the rings.  Baby the motor, and the crosshatch gets polished before the rings seat, and you're screwed.  How are race motors broken in?  They need ring seal to make power, and they don't drive them for 500 miles babying them before they race.

a man after my own heart!

[skip68]

My motor was really tight the shop said. And they said that was a good thing.    I've got about 100 miles on it and broke the new tranny mount. I've gone up and down with RPM's and shifted to lower gears when slowing down to help seat the rings. I guess the couple of stabs of the gas was to much for the stock tranny mount. 

[2Gunz]

I put in a good 10 miles of easy driving.

Then.... well....


Ok.... I flogged the hell out of it.