If everything in an engine is in good shape & there are no problems with
fit, finish and lubrication, then the critical areas during breaking are the
iron to iron or steel to steel surfaces that are lubricated by the oil film
and not by Hydrostatic lubrication. The main, rod, & cam bearings are never
really supposed to touch the cam or crank as there is a separating film of
oil that is captured and forced into the space by the oil pump. The cam and
lifters, the valve stem tips to the rocker arms, the rings against the
cylinder walls, the Timing chain, sprockets and tensioner are the critical
areas in a TR-4 type engine. The cam wants the engine to go fast enough to
keep oil splashing on it and to keep the surface speed of the lifter on the
cam high enough, but not to high, during the first 15 to 20 minutes of
operation, especially. The rings want enough gas pressure above the top
ring to keep the ring pressed against the cylinder wall so it will "wear in"
both the wall and the ring face. Again it wants enough oil to keep it
lubricated and cool, but not to much speed until the surfaces have begun to
"mate" with one another.
We always break in with Chevron Delo, Brad Penn, or Torco, which we
continue to race with.
We run at about 2200 rpm for the first 15 to 20 minutes, then shut down,
retorque the head, adjust the valves, look for plenty of oil on the top of
the head. If we are at the track, we then run 2 or 3 laps at up the 4,000
rpm using about 2/3 of WOT, then go up 500 rpm every two laps or so to 6,000
at WOT after about 20 to 25 minutes of running. What is most important is
that the oil and water temperatures remain stable. It is also good to
decelerate from 4,000 down to 3,000 with the throttle completely closed to
create high vacuum in the cylinders during the first couple of laps (make
sure there is no one behind you when you do this!), to
draw oil up into the ring belt and cool off the rings during their initial
breakin under load. By the end of the 2nd session, everything should be
well broken in. Adjust the valves hot, right off of the track so
clearances are as close as possible to the 'running" condition and
temperature. Sometime in the middle of the 2'nd session, it is good to do a
"clean cut" and coast into the pits to look at the spark plugs and make sure
there are no signs of detonation. These usually manifest themselves as tiny
black speckles like black pepper on the clean white ceramic of the spark
plug insulator. If you see any of this, retard the timing & or richen the
mixture.
Greg Solow
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