On Thu, 10 Jun 1999, Rainer Hattendorf wrote:
> Hi Bob,
Hello.
I'm cc'ing the Triumphs list, because I think your the third or fourth
person that asked me this question. Note: there are many good books on
rebuilding your engine, this sort of question is answered in those books,
and I highly recommend that anyone contemplating an engine rebuild to
read at least one to understand the process.
There's no magic here - really. It just takes time, patience and more
time to do the job right. Oh yeah, and money. And more time.
> it's now the second time a read your hint in the ListQuest regarding
"run in the cam".
Hmmm. Maybe I should stop posting to the Triumphs list... maybe my boss
will find all these posts and figure that I never do any "real work"...
but I digress. ;-)
> I'm not an professional engine engineer, so can you please explane in
> easy word what's the reson for this ?
I'm not a professional auto engineer either, believe me.
Engine break-in is critical to long engine life. Tolerances are allowed
on all parts, so nothing fits perfectly. Break-in allows things to seat
together better.
Now, the cam and lifters take some serious punishment in normal use.
There are springs, there's the "rebound" when the tappet comes off the
high point of the cam lobe etc.
At any rate, the first 20 minutes, more or less, of a cam's life is the
most crucial time period. In essence, the lifter and the cam lobe must
initially wear to a compatible fit. If not, then excessive wear will
occur to one or both, and the metal under the surface is much softer than
the surface metal. Thus catastrophic failure will follow very soon after
a bad cam installation. The cam grinder should stack the deck in your
favor by treating the cam with a surfacing agent (my words) such as a
phosphate coating. On some cams, that's the black stuff on the lobes.
DON'T WIPE THEM OFF EXCEPT TO GET CRAP OFF THEM. AND DON'T "DING" YOUR
CAM AGAINST ANYTHING HARD WHEN YOU'RE HANDLING IT!!! Oh, and if you have
a cam with no coating - GOOD LUCK!
So, the excepted practice is to do two things:
1. lube the hell out of the cam and the lifters during engine assembly.
Use a lubricant made for this purpose. Most companies that sell cams will
sell you this stuff. USE IT LIBERLLY. Note: some engines get built and
then not run-in right away. This is bad if the wrong type of assembly lube
is used, because it (the assembly lube) may drain away leaving metal to
metal contact. That is disaster on initial run-in on any motor. Regarding
the lube that you get from the cam companies - it is very "sticky", so it
will cling to the cam and lifters while you store the engine before you
run it in.
2. run the motor in as follows:
a. make sure the static timing is perfect. You want the motor to start
right away. Set the initial valve lash - loose is better than tight at
this stage, but set it so that everything runs smoothly.
b. if you can, pre-lube the motor by using pressurized oil in the main
bearing oiling "rail". If you can't do this, at the very minimum, make
sure that the rocker arms, pushrods and lifters have a liberal amount of
engine oil on them just prior to startup...
c. start the motor. If it does not fire immediately, find out why. Don't
continuously crank the motor by the starter. Trying to crank the motor
for a long time trying to fire the motor is EVIL. And it should be
uneccessary.
d. once the motor starts, bring it right up to around 2000 RPM's and leave
it there for 20 minutes. Carefully observe the oil pressure and engine
temperature. If you did everything "right", these should stabalize very
soon after starting the motor. If either gives erratic readings, shut
down and investigate - but if you do have to shut down, you still have to
run-in the cam when you fix the problem. This is one time when you really
have to have everything right when you "throw the switch" to start it.
d.1. DONT REV THE MOTOR, START IT, BRING IT TO 2000 AND HOLD IT THERE.
e. at the end of 20 minutes, shut the engine off.
f. drain the oil, change the filter and renew oil.
At this point the cam has been run-in. _IF_ everything was assembled
correctly and _IF_ everything was manufactured correctly in the first
place, you should be in good shape and for a long time. If not, well,
you'll know pretty soon. I know a few folks that put as few as 500 miles
on a new cam before a lobe broke off or wore away.
> Thanks a lot,
> Rainer
>
> '69 TR6 CC50923LO (take down the engine)
> Germany
I hope this helps.
And if anyone else has any pointers, feel free to chime in!
regards,
rml
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