Where does 1800-2000 rpm for 20 mins break in come from?

[oldcarnut]

Today I changed out a couple lifters that seemed to start ticking some.  Added some Lucas break in additive and ran the 1800 for 20 mins.  Just wondered where did these numbers come from?  I know the cam mfgs say it.  Some 2k and some 1800 rpm but how did those numbers come up?  Just seems kinda uneasy when I think about running in a new motor right off the git go up like that.  I don't ever remember the older cars when purchased new having to do that unless they did it at the factory.  Any thoughts?

[SRT-440]

Good question..I was wondering the same thing. 

[chargd72]

Isn't it just to get adequate lubrication to all the internals while keeping it at an "undamaging" rpm?  

[flyinlow]

I would think everything except the camshaft lobes would like to start up and remain at idle until fully warm. The cam lubes get most of there oil from what is thrown off the rod bearings. This oil has to fight gravity to get up to the cam. The faster the crank is spinning ,the more oil reaches the cam.
Modern moly rings have little break in requirements compaired to the plain iron or chrome rings of the 1960's. Our hand built engines we use should have little in the way of burrs and rough edges compaired to newly cast, assembly line engine originally in the Chargers, so "babying" them takes back seat to breaking in the lobes of our aftermarket higher lift,higher valve spring pressure cams. 

[John_Kunkel]

I don't know where the 20-minute 2000 rpm breakin started but I can't count the number of brand new motors we fired up and just let idle "back in the day". Never lost a cam.

[oldcarnut]

I found this on the comp site and I reckon its about getting oil to the lobes and lifter rotation as flynlow noted.  Looks to be 2k the range best for the lubing as less doesn't get enough and more puts unnecessary stress on the parts.  I thought there might have been more to it like science with heat, hardness etc figured in.  A couple places mentioned varying the rpms to direct the splash to different areas.

"As soon as the engine fires, make sure that the oil pressure comes up properly, then bring the revs up to 2,000-2,500 for the first 30 minutes. Running it slower won't provide sufficient oil flow to the lifters and camshaft, and faster puts additional unnecessary stress on them during this critical process.

Varying the engine's RPM within this range during the break-in period will help to direct oil splash lubrication to different areas of the camshaft – this can be especially important in engines with a windage tray or other measures to help control oil within the crankcase, so it's worth the extra effort. After a half-hour, the engine oil and filter should be changed (turn it off first!) to remove contaminants and break-in lube. If you followed COMP's suggestion and removed the inner valvesprings or installed low-ratio rockers for the break-in process, now's the time to swap back to your regular setup."
http://www.compcams.com/Technical/Instructions/Files/145.pdf

[Cooter]

 The factory engines were already broken in LONG before "POP" told everybody he had to "Run it in for the first 500 miles or so"..Even the dealers got in on this one as the more people did this, the less warranty the dealers had to supply...

It's funny, people STILL think new cars new to be driven "Easy" for that first 500 miles....

[firefighter3931]

With a flat tappet cam/lifter combination the lobes and lifter faces form a wear pattern during the breakin procedure. As mentioned above the cam/lifter surface is only splash lubed off the rotating assembly so maintaining adequate RPM ensures that plenty of oil reaches the critical areas. I also like to blip the throttle once a minute to ensure lifter rotation.


Ron