O.S. Engines 70SZ-H User Manual

It is of vital importance, before attempting to
operate your engine, to read the general

'SAFETY INSTRUCTIONS AND WARNINGS'

section on pages 2-5 of this booklet and to strictly
adhere to the advice contained therein.

Also, please study the entire contents of this
instruction manual, so as to familiarize yourself
with the controls and other features of the
engine.

Keep these instructions in a safe place so that
you may readily refer to them whenever
necessary.

It is suggested that any instructions supplied
with the model, radio control equipment, etc.,
are accessible for checking at the same time.

SAFETY INSTRUCTIONS AND WARNINGS
ABOUT YOUR O.S. ENGINE

NOTES ON INSTALLING,
COOLING-FAN AND CLUTCH

INTRODUCTION

BASIC ENGINE PARTS
INSTALLATION OF THE CARBURETOR

INSTALLATION OF THE ENGINE

BEFORE STARTING

FACTS ABOUT GLOW PLUGS

CARBURETOR CONTROLS

STARTING

CONTENTS

2-5

10-11

12

13-14

15-16

RUNNING-IN, ADJUSTMENTSUBSEQUENT

READJUSTMENTS
CARBURETTOR CLEANLINESS

6
7

ADJUSTING CHART

INSTALLATION OF THROTTLE SERVO

8

CARE AND MAINTENANCE

9

O.S. GENUINE PARTS & ACCESSORIES

ENGINE EXPLODED VIEW & PARTS LIST

CARBURETOR EXPLODED VIEW &
PARTS LIST

THREE VIEW DRAWING

1

17-20

21

22

23

24

25

26-27

28-29

30

SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE

Remember that your engine is not a "toy", but a highly efficient internal­combustion machine whose power is capable of harming you, or others, if it is
misused.
As owner, you, alone, are responsible for the safe operation of your engine, so act
with discretion and care at all times.
If at some future date, your O.S. engine is acquired by another person, we would
respectfully request that these instructions are also passed on to its new owner.

The advice which follows is grouped under two headings according to the
degree of damage or danger which might arise through misuse or neglect.

WARNINGS

These cover events which
might involve serious (in
extreme circumstances, even
fatal) injury.

WARNINGS

Never touch, or allow any
object to come into contact
with, the rotating parts.

Model engine fuel is poison­ous. Do not allow it to come
into contact with the eyes or
mouth. Always store it in a
clearly marked container and
out of the reach of children.

Model engine fuel is also
highly flammable. Keep it
away from open flame,
excessive heat, sources of
sparks, or anything else which
might ignite it. Do not smoke
or allow anyone else to smoke,
near to it.

NOTES

These cover the many other
possibilities, generally less obvious
sources of danger, but which, under
certain circumstances, may also
cause damage or injury.

2

Never operate your engine in an en­closed space. Model engines, like auto­mobile engines, exhaust deadly carbon­monoxide. Run your engine only in an
open area.

Model engines generate
considerable heat. Do not
touch any part of your
engine until it has cooled.
Contact with the muffler
(silencer), cylinder head or
exhaust header pipe, in
particular, may result in a
serious burn.

3

NOTES

These engine were designed for model
helicopters. Do not attempt to use it for any
other purpose.

Mount the engine in your model securely, fol­lowing the manufacturers' recommendations,
using appropriate screws and locknuts.

Install an effective silencer (muffler). Frequent
close exposure to a noisy exhaust (especially
in the case of the more powerful high-speed
engines) may eventually impair your hearing
and such noise is also likely to cause
annoyance to others over a wide area.

Check the linkage to the throttle arm before
each flight.

Avoid sudden high r.p.m. immediately after the
engine is started, as the clutch will engage and
you may be struck by the rotor.

After starting the engine, carry out any needle­valve readjustments after stopping the rotor by
closing the throttle to the lowest r.p.m..
Stop the engine before attempting to make
other adjustments to the carburetor.

Use an electric starter. The wearing of safety
glasses is also strongly recommended.
Press the rotor head down securely.

Take care that the glow plug clip or battery
leads do not come into contact with rotating
parts.

Adjust the throttle linkage so that the engine
stops when the throttle stick and trim lever on
the transmitter are fully retarded. Alternatively,
the engine may be stopped by cutting off the
fuel supply. Never try to stop the engine
physically.

4

NOTES

Take care that loose clothing (ties, shirt sleeves,
scarves etc.) do not come into contact with the
rotor. Do not carry loose objects (such as pen­cils, screwdrivers, etc.) in a shirt pocket from
where they could fall through the rotor disc.

For their safety, keep all onlookers (especially
small children) well back (at least 20 feet or 6
metres) when preparing your model for flight. If
you have to carry the model to the take-off point
with the engine running, be especially cautious.
Hold the rotor securely and keep well clear of
spectators.

Warning! lmmediately after a glowplug-ignition
engine has been run and is still warm,
conditions sometimes exist whereby it is just
possible for the engine to restart when turned
over WITHOUT the glowplug battery being
reconnected. Remember this if you wish to
avoid the risk of accidents.

5

Notes on installing cooling fan and clutch

Do not use a tool which
locks piston when
installing a cooling-fan
and clutch, or top of
the piston may be
damaged. Also, do not
insert a screw driver or
the similar into the
exhaust port.

It is recommended to use Crankshaft
Clamp 7091 (Code No.71530500) available
as an optional tool.
It is made of durable engineering plastic
and locks the crankshaft without risk of
damage to any part of the engine.

Application is as follows:

Remove the crankcase rear cover plate from the
engine and rotate the crankshaft to the bottom
dead center (BDC) position.

Insert the crankshaft clamp so that its grooved
portion surrounds the crankpin and lower end of
the connecting rod and securely tighten the fan
or clutch onto the crankshaft.

BDC position

Rotate the crankshaft so that the
connecting rod comes to this position.

Insert this groove onto
the connecting rod.

6

INTRODUCTION

This is a high performance engine designed
for 3D flight as well as F3C competition.
It may be replaced with the current 60 size
helicopter engine without changing the gear
ratio as the mounting bolt pattern is the
same. Also, the six mounting bolt pattern
increases fore and aft rigidity. New design
60K carburetor has three adjustable controls
which enables independent adjustment at
idling, hovering and high speed.

Standard accessories

Carburetor Type 60K-C
Carburetor Rubber Gasket
Carburetor Sealing Washer
Carburetor Retainer Assembly
Glow Plug No.8
Woodruff Key
Needle Adjusting Screw (2.6x5 2pcs.)
Instruction manual

Note:

As delivered, the carburetor is not fit to
the engine.

Note:

Because of initial tightness, a standard
electric starter may have difficulty in
rotating the engine when cold, before it
has been adequately run-in. In this case,
use a high-torque type starter.
DO NOT, however, confuse tightness
with the symptoms of hydraulic lock
caused by an excess of fuel within the
cylinder - often the result of over­priming.
Attempting to force the engine to turn
over in this condition may cause
internal damage. Instead, remove the
glowplug, invert the engine and eject
surplus fuel from the combustion­chamber.

7

BASIC ENGINE PARTS

Carburetor T ypr 60K

Heatsink Head

Carburetor
Rubber Gasket

Carburetor
Sealing Washer

Carburetor Retaining
Screw

Carburetor Retainer

Crankshaft

Thrust Washer

Beam Mount

Crankcase

Glowplug

Cover
Plate

INSTALLATION OF THE CARBURETOR

Fit the carburetor rubber gasket to the carburetor
body.

Insert the carburetor seal washer into the
carburetor fitting hole to the bottom.

Insert the carburetor retainer into the holes shown
left and fit the carburetor to the engine.

Loosen the retainer screw, rotate the carburetor to
its correct position and press it well down into the
intake boss, compressing the rubber gasket as
shown in the sketch, before re-tightening screw.

Rotate the retainer screw gently until it stops, then
tighten a further 120-180 degrees. Do not over­tighten the screw as this will damage the thermo­insulator.

Carburetor Rubber Gasket

8

Retainer screw

Positioning Mark

0.2mm gap

INSTALLING THE GLOWPLUG

Install the washer on the
glowplug and screw
carefully into cylinder­head, making sure that it
is not cross-threaded
before tightening firmly.

Glow plug

Washer

INSTALLATION OF THE ENGINE

The under-surfaces of all O.S. engine beam
mounting lugs are precision machined flat and
exactyly parallel to the engine's horizontal axis. It is
essential that the engine mounts in the model are
also accurately made and aligned. If they are not,
they will cause stress and distortion within the engine
itself, probably resulting in loss of performance and
internal damage.
The recommended screws for securing the engine to
the engine mounts in the model are 4mm or 6-32 NC
steel Allen type. It is also advisable to use lock
washers or LOCTITE to prevent nuts from loosening.

CORRECT

Front view

Top surfaces are in the same plane.

INCORRECT

Top surfaces are not
in the same plane.

Re-align the surfaces as necessary
Make sure that only the under-surfaces

of the engine’s mounting lugs are in
contact with the engine mount.
If the crankcase body touches the
mount, chamfer the edges of the mount.

9

Side view

Top surfaces are not in the
same plane.

Engine does not rest firmly.

BEFORE STARTING

Tools, accessories, etc.

The following items are necessary for operating the
engine.

1 Fuel

Select, by practical tests, the most suitable fuel from
among the best quality fuels available in your country
for helicopter use. For the best throttle response, a
fuel containing 10% to 30% nitromethane is
preferable. Lubricants may be either castor-oil or a
suitable synthetic oil (or . a blend of both) provided
that they are always of top quality. For consistent
performance and long engine life, it is essential to use
fuel containing AT LEAST 18% lubricant by volume.
Some fuels containing coloring additives tend to
deterriorate and may adversely affect running
qualities. If in doubt compare to a fuel known to be
good.

Reminder!

Model engine fuel is poisonous. Do not allow
it to come into contact with the eyes or
mouth. Always store it in a clearly marked
container and out of the reach of children.

Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
which might ignite it. Do not smoke, or allow
anyone else to smoke, near to it.

2 Glowplug

O.S. No.8 glowplug is installed in the engine.

3 Battery leads

These are used to conduct current
from the battery to the glowplug.
Basically, two leads, with clips, are
required, but, for greater conve­nience, twin leads with special
glowplug connectors, as shown on
the right, are commercially available.

Battery leads

4 Glowplug battery

The power source for heating the glowplug may be
either a large heavy-duty 1.5volt dry cell, Ni-cd battery
or battery integrated booster.

1.5 volt dry cell

Battery Integrated booster

10

In case of 1.5volt dry cell

Make sure glowplug element
glows bright red inside room
or shadow.

5 Hexagon starting shaft

This shaft mounted on an
electric starting motor is driven
into the shaft cup to turn the
engine.

6 Electric starter and starter
battery

An electric starter is recom­mended for starting.

Battery leads

12V Battery

Starter

7 Fuel pump

For filling the fuel tank one of the
purpose-made manual or electric fuel
pumps may be used to transfer fuel
directly from your fuel container to the
fuel tank.

8 Fuel container filter

Install a filter on the outlet tube of your
refuelling container to prevent entry of
foreign matter into the fuel tank

9 Silicone tubing

This is required for the connection
between the fuel tank and engine.

10 Plug wrench

Used for tightening glowplug. The
O.S. long plug wrench is available
as an optional accessory.

11

Fuel pumps

Manual

Fuel Can Filter

Silicone tubing

For tightening
glowplug

Electric