Have heard so many scenarios, What is the right way to break in fresh motor? Never had one rebuilt just the new ones. 502 Mag new pistons, cam, lifters the works, with a little head work. Just really want to know from the experienced few... What is the right way?

Thanks,
Rocket

I will also be breaking in my rebuilt 454 Mag this week. Told by the engine builder to run at 2100 - 2300 for 20 minutes to break in the cam. Then change the oil. For the next ten hours try not to idle for long periods and run 3100 - 3900 (can run higher for short bursts) varying speed often. Then change oil again. I have faith in my builder (built motors for Moroso), so that's the plan I'll follow.

Hope this helps,

Scott

let it have it!! u don't break-in a chain saw saw'n twigs now do ya!!??

hell that's more than 1/2 a race season!

I like the idea of "let it have it!" but ..... Ive tore up a hell uva lot more chainsaws than 5 grand worth of rebuild Chevy Big Blocks. Are you serious is there no real way. Come on Mercury has all the little does and donts when you buy a new toy, but hell thats warranty ****. I dont thimk I could afford the divorce if I screwd this motor up. I had a hard enough time convincing I needed more HP. Not a lot of sponsorship here!

My dad has built motors for 30 yrs and he and I have never babied a new motor... except for camshaft breakin... we mostly run all roller cams. no breakin. just drive it like ya stole it..

your best mile will be the first mile . if you have faith in your builder run it. although I run mine about ten miles easy, shut it off look for leaks check things over, let it cool down and go see what it does. good look no one likes engine problems.

Cam break-in is CRUCIAL! {Non-Roller lifters} After that......Run the sumbich!!!!!!!

.....W F O.....

Cam break in is critical (non roller)
But after that it depends on how the cylinders were finished.
If they were honed with a real fine stone then it will take longer for the rings to seat, that is why they don't recommend usning synthetic on a new motor.
The motors that I have had done have not had the cylinders honed that fine so basically break in is "drive it like you stole it !"

I would say a few hours, and change oil. I think on brand new merc motors, they run really rich for the first 30-40 hours, at least mine did. Then it leaned out. MY 2 cents.

WILL