Engine run in procedure

[Miniac]

Successful Engine Run-in .
Installing a new rebuilt engine in your car
will give it a major “shot in the arm” in any
number of ways. In order to get the most of
this change we suggest that you take the
time while the engine bay is empty to do a
thorough cleaning of the area.
We suggest you carefully examine such
items as motor mounts; fuel, water and
clutch hoses and replace them if they are
cracked or stressed. This is also a good
time to have the radiator checked by
reputable shop and have any necessary
repairs done. Be sure to check the condition
of your electrics, looking for corroded
connectors and frayed and /or broken wires
(including battery and ground cables) since
a bad ground or corroded connection can
take away all the performance you are
buying!
Also carefully examine your fuel and
hydraulic lines and repair or replace them
now, while you have the room to do it
comfortably.
This is also the time to carefully check the
carburetor(s) and rebuild if required. Look
closely for play around the throttle shafts,
since air can leak past a worn shaft and
give you fits at tune-up time. Check and
replace points, cap and rotor as needed
and look for excess play in the distributor.
Remember, some of our cars are 40 years
old or better, so make the extra effort to
give that new engine a good home!
Run-in Procedures
Read these procedures thoroughly before
starting your engine. Have a good shop
manual nearby.
Your Mini Mania rebuilt engine comes to
you in a DRY condition. It has been put
together with quality assembly lubricants in
all the areas of high stress and extreme
pressure, such as the cam and lifter
interface, the crankshaft main and rod
bearings and the valve train. It has not
been pre-run or dynoed, so you will need
to “prime” the oil pump while filling the
sump for the first time.
To do this, remove the ”banjo” bolt at the
upper rear of the engine and fill the
passage leading to the oil pump with motor
oil. Replace the bolt.   Fill the oil filter with
oil and replace. Continue to pour the rest
of the required amount of oil through the
oil cap. Use a high-quality oil such as
Valvoline, Castrol or Pennzoil. Never use
"bargain" oils in your engine at any time!!!
The money you "save" will be spent any
times over in maintainance costs at a later
date. DO NOT, DO NOT, DO NOT use
synthetic lubricants of any kind in this
engine at any time! This is particularly
important for Mini owners who have to
lubricate both the engine and the
transmission with the same oil!
Remove the spark plugs and turn over the
engine with the starter until the oil
pressure gauge shows full pressure.
Be sure to correctly fill the cooling system
with the correct mix of coolant (anti-freeze)
and water according to the manufacturers
recommendations (also found elsewhere in
this database) or use a water pump
lubricant in the water.
Re-install the plugs and prepare to start the
engine. The carburetor should have the jet
tubes set 2 turns down from flush with the
bridge and the needle(s) centered in the
bore(s).
Start the engine and hold the engine speed
at 2000-3000 RPM for at least 20 minutes.
This ensures plenty of oil to the camshaft
bearings. Speeds slower than 2000 RPM
may starve a cam of oil. You may want to
do this during the day to avoid
disagreements with your neighbors.
After this initial run-in, retorque the
cylinder head, HOT, to 50 ft/lbs and
readjust the valves according to your shop
manual.
Do not exceed 3000 rpm for any prolonged
period for the first 500 miles, at which
time, change the oil and readjust the
valves. After this you may gradually increase
RPM limits over the next 1000 miles or so.

[Boyscout]

There are two schools of thought on the run in procedure. This one from Mini Mania is the conventional way. I agree with every thing said except the part where it is stated to keep the RPM under 3000 for first 500 miles.

My opinion is that there is a very limited window of opportunity to bed the rings into the newly honed cylinder walls. I suggest starting up as per the above mentioned procedure, make sure there are no leaks, oil pressure is up to spec, then after it has run for a few minutes with no obvious signs of trouble and overheating, take it for its first drive. Once at operating temperature, you need to nail it for short bursts. That means you have to floor it. This allows the rings to properly expand and bed into the newly honed surface. I'm not saying you need to drive it like you stole it but you need to take it to full power for short bursts. You also need to vary the RPMs to cover the whole range, again don't rev it to valve bounce but at least to 5000RPM. this will allow the conrods to reach full flex and then it won't produce a ridge in the cylinder wall. Once you have done this a few times, whilst checking all the vitals, then the engine can be driven normally. After about 1000Kms you should drain the oil and fit a new filter.

This is the way I treat a new engine and have never had any issues. We did once have an issue on a VW race car where we didn't floor it soon enough. This engine had excessive oil consumption and the rings never bedded in. Had to rebuild again. On the consecutive rebuilt we followed the "nail it" procedure and the engine power and oil consumption was as it should be.

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Copied from this web site http://www.mototuneusa.com/break_in_secrets.htm

Warning:
This is a very controversial topic !!

I wrote "Break-In Secrets" after successfully applying this method
to approximately 300 new engines, all without any problems whatsoever.

Links to this article now appear on hundreds of motorsports discussion forums from all over the world. The reason is that over time, large numbers of people have done a direct comparison between my method and the owner's manual method, and the news of their success is spreading rapidly.

The results are always the same... a dramatic increase in power at all RPMs. In addition, many professional mechanics have disassembled engines that have used this method, to find that the condition of the engine is much better than when the owner's manual break-in method has been used.

The thing that makes this page so controversial is that there have been many other break-in articles
written in the past which will contradict what has been written here.

Several factors make the older information on break-in obsolete.

The biggest factor is that engine manufacturers now use a much finer honing pattern in the cylinders than they once did. This in turn changes the break-in requirements, because as you're about to learn, the window of opportunity for achieving an exceptional ring seal is much smaller with
newer engines than it was with the older "rough honed" engines.

In addition, there is a lot less heat build up in the cylinders from ring friction
due to the finer honing pattern used in modern engines.

The other factors that have changed are the vastly improved metal casting and machining
technologies which are now used. This means that the "wearing in" of the new parts
involves significantly less friction and actual wear than it did in the distant past.

With that in mind ...

Welcome to one of the most controversial motorsports pages on the internet !!

How To Break In Your Engine For
More Power & Less Wear !

One of the most critical parts of the engine building process is the break in !!
No matter how well an engine is assembled, it's final power output is all up to you !!

Although the examples shown here are motorcycle engines,
these principles apply to all 4 stroke engines:

Street or Race Motorcycles, Cars, Snowmobiles, Airplanes & yes ...
even Lawn Mowers !!
( regardless of brand, cooling type, or number of cylinders. )

These same break in techniques apply to both steel cylinders and Nikasil, as well as the ceramic
composite cylinders that Yamaha uses in it's motorcycles and snowmobiles.
What's The Best Way To Break-In A New Engine ??
The Short Answer: Run it Hard !

Why ??
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.

How Do Rings Seal Against Tremendous Combustion Pressure ??

From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.


The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!

An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!

[BRAAAP]

interesting..... i pushed mine under load most of the time.. some nice long uphills here in CPT to load the motor in low revs.... car runs very well now.