Theoretical situation: Block and rotating assembly are fresh from the machine shop. Block is decked slightly to clean up the gasket surface and true the deck 45 degrees to the crank center line. Block is bored over with new pistons and honed for the exact ring size, filed to fit the hone. Caps have been cleaned up and align honed and the rotating assembly balanced to perfection. Brand new, out of the box camshaft is put into the motor during the rebuild along with new springs and lifters.

Now...here's where I'm getting conflicting information. Break in procedure. Any new motor needs a soft break in period at varying RPM levels for certain durations at those levels, starting with the longest at 2000 RPM for 20 minutes; basically to seat the rings and ensure proper lubrication, and that nothing is leaking. During this time, engine temperatures are monitored, hoses are checked, timing is figured out along with idle, thermostat opens/closes at the right time and to also ensure the fan(s) come on when they're supposed to. The dealership asks for about 500-1000 miles of 'babying' the motor, followed by a quick oil change soon after.

The information that conflicts with the above is the camshaft break in procedure for hydraulic roller cams. I have read and been told that the new LS based camshafts need to have the living crap kicked out of them to break in the cam properly. If I may quote one guy, "...with a new cam, break it in like you stole the car...".

How is a new engine then supposed to be 'worn in'? Or better yet, which procedure gets seniority?

Thanks for reading.

 

I've never heard that the hydraulic cams need any braking in, maybe the advice was meaning just drive it normal?

 

yea ive never heard that either, i drove mine easy for a day or two then went wot!

 

Ls1tech has a good thread going on in the advanced tech. sec. about this.I would explain my theroy but, I think you will get more out of some of the post over there.That and I am not patient enough to type it all out.

 

post a link to the tech thread!

 

Sorry,I can't post links from my phone.

 

I think I found it.

https://ls1tech.com/forums/showthread.php?t=672793

Good find, I'll read this tomorrow when I don't have to be up in 4 hours for work.

 

havent read the link, but I can tell u this: Having poorly broken in my motor and washing the rings, thus rebuilding/rehoning, I broke it in very slowly and very easy the second time - and that included a new cam. I was never in the WOT camp to begin with, but was convinced that a motor/cam cud be broken in in a matter of hours using dyno and street by working the proper tables and careful monitoring. Whether it was the shop or the method I'll never be sure, but I can guarantee you that slow and easy for the first 2000 miles at least will never fail. The arguement is that the "old" way I last mentioned isn't required for today's tighter tolerances, and better materials... I'll just say I've learned a new definition of patience/$ ratio! R/

 

 

I don't believe in breaking a motor in but I DO BELIEVE they break in. What I mean is, don't baby it but don't beat on it either. Drive like you do everyday. I always hop on the highway right away and usually go on a 60 mile road trip with any new motor I build. This means blasting it on the entrance ramp, then gently cruising for 20-30 miles, getting off the highway, driving through a town, take back country roads, up and down hills. Heavy throttle up hills, no throttle down hills (allows the crankshaft to put pressure on both sides of the bearings) and then a nice drive back on the interstate at 70 MPH or so. As far as these roller motors go, there is no valvetrain break-in whatsoever except for Springs. The only thing you're really breaking in are the rings and bearings. If it's any consellation to you, I bought my Silverado new with 6 miles on it in Blanchard, OK, hit the interstate with about 15 miles on it and drove 80 MPH on a new engine and truck back to Minneapolis without stopping except for gasoline. You cannot hear my motor run and it's extremely strong for a 4.8L.