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Thread: Engine Break-in

  1. #1
    Tom Senior member Iggy's Avatar
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    Mar 2013
    Traverse City, MI

    Engine Break-in

    The question comes up a lot - What is the correct Break-in procedure? What I am describing is what I have done for some 40 years, I have only had one issue where I dropped a valve, but have never had an issue with a cam.

    I use either 10W-30 or 10W-40 conventional motor oil and add a bottle of Lucas Break-In Lube, I also put a magnet on the oil filter to try to trap the metal shavings from the rings seating. I will pre-oil the engine using a pre-oiling tool and a drill, I turn the engine over two complete revolutions by hand while pre-oiling to make sure all of the lifter are filled. Keep in mind, I have assumed that you used moly lube on all of the cam lobes and set the lifter pre-load (those are really part of assembly, not break-in). Once done pre-oiling, make sure you are at TDC compression on #1 and drop the distributor in setting as close to 0* as possible - you want to fire up the engine and immediately increase the RPM.

    Here is the run procedure I use for breaking in with a flat cam. As I mentioned, fire the engine and immediately get the engine speed to 2,000 RPM. Run the engine for 20 minutes varying the engine speed between 2,000 and 2,500 RPM. This engine speed allows the lifters to spin as the cam turns so the lifter and cam can wear a pattern into each other, it also allows the rotating assembly to splash oil on the pistons and rings so they seat properly. Another thing that many do not think about, this procedure also breaks in the valve springs. Once the initial 20 minute run is done, drain the oil asap while the contaminants from fuel and break-in are suspended - also change the oil filter. If possible, at this time I like to drop the oil pan and clean it out to make sure I get as many of the metal shaving out as possible.

    If you have a roller cam, the only real difference in the break-in procedure is the RPM is not as critical as it is for a flat cam, but you still need enough RPM to splash oil on the cylinder wall to properly seat the rings and enough to the top end for the valve springs - Chevy small block gen I and big block Mark IV are famous for not getting enough oil to the upper end.

    After the initial break-in, put fresh conventional oil and filter in the engine, if you have a flat cam add a zinc additive (or use break-in lube) with each oil change or get an oil that has high zinc levels like a racing oil. Run that for 500 miles and drain again - this is to make sure you are done seating the rings and again to flush out any remaining metal shavings. After that I still like to run conventional motor for another 2500 miles. Once I have a total of 3,000 mile on the new engine I will switch to a synthetic oil - I use AmsOil Z-Rod for my flat cam engine as it has the extra zinc.

    Again, I would like to point out this is the procedure I have been using for 40 years - it may be overkill but when you have $3,000 or more in a mild build I do not want to risk blowing it before I even get to use it!
    Last edited by GobblerK5; 10-10-2017 at 01:44 PM.
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