We were able to get the 418 together this weekend, get it in the car, and break in the cam. Good pressure, stays cool, no leaks. Sounds radical and is a torque monster from what we have felt. Took it out a couple of times for total of about 15 miles. Going to Mo-Power on Friday. How many break-in miles between now and then to be safe? What should be my RPM limit until then?

Thanks,

P.S. Bear with us, but we could have a lot more posts/questions in the following week. Thanks to all who have chimed in with all of the help to this point.

change the oil, and then get a load on that thing asap. wring it's neck. don't be afraid.

I would hate to give you the wrong advice,but you have already done all that I do before running them. I do not buy into that 500-1,000 mile break-in period.

you are probably not running cast iron rings anymore drive it like you stole it

I get them up to temp, run the valves and make 10-20 pulls on the dyno. Rings seat almost instantly, no cam break in on a roller.

I've always heard to double check all your bolts & lash, be sure about how you have it timed, check carefully for vacuum leaks, spend some time reading plugs to get the jetting right or put a wide band on it, and run it like you are going to use it. Always make sure to have it warmed up before you beat on it.

I had maybe 30 minutes run time on mine before I hit the track with it

On any street motor I like to seat the rings under acceleration and deceleration. Run it up to 60 - 70 m.p.h. and let her coast down to 40 or so and run it back up with firm , but not flat footed pedal pressure.
Repeat this three or four times and then commence to enjoying it.
Change oil shortly afterwards and inspect the filter , call it good.
I don't buy the 500 mile break in either.

If it was machined dead-nuts true and square, you should be able to trash it as soon as you seat the rings

Tubtar has it right but it's always good to run the valves again right after the first fire-up to operating temps. You don't want a loose rocker getting looser the first time you nail it.

The machine shop and the cylinder wall finish will determine how quick the rings seals BTW, SB( 10 head bolts) take longer than BB or Hemi on the dyno to reach peak power, 8 to 15 pulls BB and Hemi take 5 to 10 pulls to reach peak power

if all is done correctly i make one medium pass to make sure nothing falls off the car.
Then 6200 and launch

run em in fast & they go fast. i just give them 3-4 heat cycles, drain the oil, retorque everything & then go lean on it with a quality oil pumping.

I ran mine to break in the cam then let it cool checked the valves changed the oil , then burnout stage and sprayed the house thru it..

Lots of factors.
But ring type (cast, moly, etc), cylinder hone finish, bearing clearance, piston to wall clearance, piston material, ring end gap, etc. etc. etc.

But if built for racing, after 20 minutes to seat the moly rings, it is ready for full power....

That is after checking everything, everything. And changing the oil and filter.