Reprinted from Goblins' Gazette, November 1993
Copyright John Fowler 1979,1993, All Rights Reserved
Goblins Gazette is the monthly magazine of the Austin Healey Sprite
Driver's Club Inc (Victoria, Australia).
This is reprinted verbatim, and represents John's personal advice. No
warranty is expressed or implied - use this advice solely at your own
risk. Double check with other sources etc etc etc.
Hints for Spridget Owners
In July 1979, John Fowler put together a comprehensive list of tips
for Sprite owners. Whilst some of the more senior members (of AHSDC)
may have seen these before, there are enough young whipper snippers
around to print them again. It may also be interesting to note any
differences in opinion between 1979 and now. Schools of thought
change, and the chase for power makes old theories obsolete. In
particular, Vizard's book "Tuning the A-Series Engine" provides a very
comprehensive guide to improving your sprites engine performance. You
should also discuss your ideas with one of the old guard before
proceeding with major modifications.
Part I - General
1.1 One possible engine development combination that has been
found to be a successful 'sporty' road and competitive track engine by
a number of club members is as follows:
Stage 1:
Thomas 66Lt cam grind, high compression pistons, competition
valve springs, complete engine balance, 1.5" SU's or a 45 Weber, long
manifold and extractors.
Stage 2:
Balanced distributor, worked head, competition clutch,
Dyno-tune, lightened flywheel, oil cooler and Tuftrided crankshaft.
This is a good combination which is not 'lumpy' in the lower
rev ranges and has excellent mid-range torque with a power peak at
around 6000 to 6500 rpm when employed with a 1275 engine. This uses
Cooper S pistons and MME needles in 1.5" SU's or Weber settings as
appropriate. It uses a Hillman Hunter clutch and produces about 90 to
95 bhp.
With a 1098 engine, Weslake flat top pistons, AO or number 5
needles in 1.5" SU's, 'Duplex' timing chain and gears and a harmonic
balancer could be used.
With 948 engines, Formula Junior raised 'D' crown pistons,
Mk2A con rods, 9 spring clutch, harmonic balancer, 998 Cooper head
casting (12G 295) and 'Duplex' timing chain and gears could be used.
1.2 In order to obtain maximum performance from a modified
camshaft and to smooth out its 'lumpiness', the distributor should be
rebalanced to suit (without vacuum advance mechanism). Alternatively,
a Cooper S type could be used, with leads off the side of the cap.
1.3 For maximum torque, fit as long an inlet manifold as possible.
About 9" from the carby butterflies to the valve stems is ideal.
1.4 When rebuilding an engine, Holden (HQ?) flywheel bolts should
be used, as they are MUCH stronger than the originals.
1.5 For greater efficiency (hence economy and power), the sides of
the 'side' electrode of your spark plugs should be filed square, which
improves the strength of the spark. On most engines from mild to full
race engines, the spark plug which usually gives best performance is a
Champion N7Y (or equivalent) gapped to 0.024".
1.6 Unless the engine rear oil seal is leaking, do not remove the
'half moon' seal when rebuilding an engine. But if it is leaking, then
adjust it as follows. Fit and finger tighten the 3 bolts so that the
'half moon' seal is approximately level with the edge of the block.
Fit the bearing cap and torque down to 20 foot pounds. A '2 thou'
feeler gauge should just slide in on each side of the seal. Nip the 3
bolts up lightly. As the cap is progressively torqued down the gap
will lesson between the seal and the cap. As a further aid to prevent
leakage (particularly on worn seals) oil the crankshaft slinger
lightly and thinly apply Silastic to the seal in the cap and on the
'half moon'.
1.7 When rebuilding an engine it is a wise precaution to 'Loctite'
the nuts and bolts of any moving parts. On high revving race motors
big end nuts and bolts should periodically be replaced with new ones
to prevent metal fatigue, which could cause a big blow up.
1.8 Remember when you torque down the head to re-set the tappets,
which will probably have closed up slightly. Also, when re-tighteneing
the head (from the centre outwards) remember to 'crack off' each nut a
quarter of a turn before re-tightening to the correct tension.
1.9 To make it easier to remove the starter motor or the engine at
any future time you can weld a semi-circular joining bracket between
the heads of the starter motor mounting bolts. Then fit the bolts with
their heads on the gearbox side. This will stop the bolts from
spinning as you undo the nuts. This is normally a very awkward job.
1.10 When the engine is removed, it is a good idea to shorten the
clutch slave cylinder bolts by about 0.25". This allows the slave
cylinder to be easily removed whilst the gearbox is still in the car.
Normally the bolts can only be partly undone before fouling on the
chassis rail.
1.11 If you have the engine and gearbox out of the car for any
reason, it is a good idea to replace the slave cylinder rubbers,
clevis pin and push rod while they are easy to get at. Note: make sure
that the new pushrod is the same length as the old one.
1.12 If the clutch feels like it is worn, or if there is little
pedal travel, then first check (and replace if necessary) the clevis
pins at the master and slave cylinders and the slave cylinder pushrod.
Occasionally when another clutch is fitted it fails to operate
correctly. This can be overcome by using different length pushrods.
Weld an extra piece in, cut a bit off, or find a replacement of the
right length (like a Cooper S pushrod, which is longer).
Alternatively, an adjustable pushrod can be made up from a Holden one.
1.13 Make sure your car still has an earth strap between the engine
and the body. Without one, the choke cable is often the only earthing
point and can get quite hot! The engine can also be difficult to
start.
1.14 The water temperature sender unit gives a safer and more
accurate reading if it is fitted to the head (as in later models).
However, if you fit the sender to the head you will need the Smiths
spacer (part number M44708) to prevent the bulb being squashed inside
the head.
1.15 On high revving race motors, a Ferguson tractor pulley should
be fitted to the generator. This will prevent the generator spinning
itself to pieces and reduce the load on the engine, giving better
throttle response.
1.16 An alternator delivers full charging output at much lower revs
than a generator, which is perhaps more suited to higher revs. This is
why alternators are fitted to V8's. But don't be in a rush to fit one
to your Sprite, as there are few (if any) advantages. Midget
alternators and regulators are often unreliable and expensive to
repair. By making up some simple brackets and spacers an early Holden
Bosch alternator and separate regulator (adjustable) can be fitted.
They are cheap and easy to repair.
1.17 Never fix the exhaust system solidly to the body chassis
(unless a section of flexible exhaust pipe is used) because when the
engine vibrates back and forth something has to give. Usually the
floor, pipe or manifold. A simple trick is to cut a strip of rubber
out of the side wall of an old tyre, punch two holes in it and attach
one end to the body and another to a 'D' clamp on the exhaust system.
1.18 When removing the engine it is a good idea to leave the rubber
engine mount and bracket attached to the chassis on the driver's side,
but remove the mount on the passenger side. This saves a lot of
fiddling when refitting the engine.
1.19 A lower radiator hose can be cut in half to make a top hose,
so is a good spare to carry in the boot.
1.20 To stop vertical movement of the steering column, fit new
Morris 1100 steering column bushes. A nylon upper and a felt lower.
1.21 Loose steering columns which move in and out will wear the
splines on the rack, so remove the column and file a bigger gap where
the pinch bolt goes. This will allow the column to grip the spline on
the rack tighter. If this is not enough, you can drill out the bolt
hole, fit a larger bolt and file a SLIGHTLY deeper groove in the rack
spline. You can also use a shim if necessary, but if things are that
bad then it is probably advisable to replace the worn parts. (Eg. the
end of a column from a Morris Minor can be used). If a second hand
column is used, then you can reduce wear by having it heat treated
before installation
1.22 To remove the steering arm ball joint, partly undo the
castellated nut, place a lever between the steering arm and steering
rack, then exert pressure on the lever to attempt to free the ball
joint. At the same time, tap the steering arm sharply, all around
where the ball joint is attached to break the seal where the tapered
shank of the ball joint has 'welded' itself to the steering arm. The
ball joint should come free all of a sudden.
1.23 The two bolts that hold the steering arm onto the stub
assembly often work loose and damage the thread. Make sure that high
tensile bolts ONLY are fitted, and tighten them up to 30 foot pound
with a little 'Loctite' just to be sure. The same applies to Shock
absorber mounting bolts.
1.24 Fulcrum pins on the front suspension wear out regularly. Have
you checked yours recently? They should be greased about every 500
miles for longer life. When replacing the fulcrum pins, the cork 'O'
rings often break and no longer hold the grease in, allowing the
fulcrum pins to run dry. It is recommended that you fit 0.75" tap
washers instead, as these are much more robust and easier to fit. One
side on each fulcrum pin will need to be enlarged on the inside to fit
over the thicker end of the pin.
1.25 When fitting disc brakes to a Mk1 or Mk2, make sure you use
their larger diameter king pins and the later model, smaller bore
master cylinder, which has a different valve setup and does not hold
line pressure like the Mk1 or Mk2. Because of the larger diameter rear
wheel cylinders on early cars, a low pedal results, so you are best to
switch to the later model setup at the rear as well. You could use the
wheel cylinder from the 8" rear of a Lancer/Major, but this can cause
premature rear wheel lock-up with Sprite disc brakes at the front. It
is however a good choice if you swap to a Cortina front disc setup.
1.26 When a power booster is fitted to the brakes, it should be
fitted below the level of the top of the master cylinder. For example,
fit the booster in the depression where the inner guard meets the
footwell.
1.27 A good idea in order to keep an eye on the level of hydraulic
brake fluid is to fit a plastic Mini 1100 extension tube too the
master cylinder. This is an important addition where a power booster
is fitted, because the hydraulic lines are often raised above the
level of the master cylinder body.
1.28 The wheel nuts on cars are often left un-tightened by
accident, not tightened enough or over-tightened. This can cause
wheels to come loose, elongation of the holes (at least) or if
over-tightened, can cause the wheel centres to crack. To avoid any of
these things happening, it is a good idea to tighten your wheel nuts
with a torque wrench to 45 foot- pound.
1.29 If you have wire wheels, periodically check that your knock
off nuts are tight. They do work themselves loose! Remember to grease
the splines on wire wheel hubs so that they are always easy to get
off. Otherwise they can freeze or even rust on. Also, when removing or
refitting wire wheel knock offs, make sure that the wheel is off the
ground, that the brakes are off and that the car is out of gear. This
will prevent damage to springs brakes and transmission from jarring.
1.30 On vehicles with flared guards or one piece bonnets, soil,
water and so forth are often thrown up into the engine compartment by
the wheels. To overcome this, you can fit a firm plastic extension
strip (horizontally) to the inner guard - wide enough to meet the
bonnet/outer guard.
1.31 Two speed wipers CAN be fitted to a Sprite. The part number is
12V 0 75462B DR 3A 10 63. Note: If other two-speed types are chosen,
check that the arc of the blades is similar to the original. The
degree of the arc should be marked inside on the large gear wheel.
1.32 On cars with forward hinged bonnets, a simple idea to stop the
bonnet resting on the ground and damaging paintwork is to fit part of
an old retractable seat belt between the bonnet and the bulkhead above
the battery.
1.33 Under the windscreen pillars on Sprites from Mk1 to Mk2A,
where they bolt to the body, there should be rubber gaskets. If these
are missing, cut a pair from an old tyre tube. The gaskets allow the
pillars to fit better, stop the duco being marked and help prevent
water from running down the bolt threads to rust out the bulkhead
pillars. Silastic around the bolt holes also prevents water entering.
To prevent the bulkhead pillars from rusting out, drill a hole into
the base of the pillar under the hinge whilst the door is open. This
will let the water out.
1.34 The striker plates for the door locks on early Sprites can
wear out quickly. To prolong their life, close the doors with the
catch depressed and then release the lever.
1.35 Austin A30's are a good source of parts for Sprites - the
front suspension, drum brakes, differential centre, rear axles,
grommets, electrics, door check straps, etc. But remember that A30
wheel centres are weaker than Sprite centres!
Austin A40 Farinas provide front suspension, 8" drum brakes,
differential centre, wheels, motor (948), gearbox, electrics, etc.
Morris Minor 1000's provide drum brakes, diff centre, rack and
pinion steering, motor (948), gearbox, electrics, wheel centres (for
turning down to fit wide wheels) etc.
Part II - Competition
2.1 Do not remove air cleaners for motorkhanas - a lot of dust is
often present that could damage engines. Remember too, an oiled foam
element is more effective and efficient than any other sort of air
filter.
2.2 Increase the carburettor's idle speed to 1500-2000 rpm when
competing - especially on a weber carburettor. This prevents flooding
and the engine stalling when you stop suddenly or spin during an
event.
2.3 In speed events, in order to get more instantaneous
acceleration out of corners, remove all but a trace of oil from the
dampers in the SU carburettor dashpots. (it is not desirable to do
this for the stop-start conditions on the road.)
2.4 In speed events, especially hill climbs, make sure that you
have enough petrol in your tank to prevent the petrol pump sucking
air, when cornering hard and petrol surge occurs. This means usually
at least half a tankfull; otherwise engine misfiring will occur.
2.5 In speed events it is often advisable to overfill the oil by
1/2-1 pint. This keeps oil around the sump pick-up and prevents it
sucking air when the oil surges under hard, fast cornering. Better
still, baffles could be fitted in the sump and/or a deeper sump and
pickup fitted.
2.6 If oil pressure is lower than specified, first of all check to
see that the Oil Pressure Relief Valve has been seating correctly. If
it has not, then replace with a Cooper S spring and plunger.
2.7 An oil cooler can easily be fitted. This increases oil
pressure slightly and maintains pressure when the oil is hot. In hard
competition, especially with a modified engine, it prevents oil from
boiling on the crankshaft bearings.
2.8 A top quality oil should be used in the engine, and this,
along with the oil filter, should be changed frequently and regularly.
Remember, oil is cheaper and more convenient than an engine rebuild.
2.9 To increase gearbox life on all models after the Mk I (with
its bronze bushes and thus a need for the light oil), a heavier grade
oil - EP90 - should be used. This helps maintain a film of oil on the
gear surfaces at high revs. Also a tube of "Molybond" in the
gearbox has been found to make the synchro work even better.
2.10 A higher grade diff. oil could also be used - a B.S.D., EP90,
oil would be ideal for extending the diff. life.
2.11 1.5 inch SUs with the vertical mounting holes (from MG, Rover,
etc) can be fitted straight onto the later sprite manifolds (which
have been filed out and enlarged to 1.5" at the outer face only). When
the correct needles are fitted, this can result in a large increase in
HP. Or, a more expensive Weber plus manifold can be bought and fitted.
2.12 The fan-belt pulley on the crankshaft of sprites can be
replaced by a heavier harmonic balancer pulley from a Morris 1100 etc.
This dampens down crankshaft whip and vibrations and leads to longer
bearing and crankshaft life (especially on Mk Is).
2.13 Check all catches on bonnets hinged as standard at the rear.
These can wear or become misaligned so that the bonnet could easily
fly up at speed events, and partly bend the bonnet, hinges and
firewall scuttle. This is even more likely to happen on the highway
when a truck passes. It may be desirable to fit extra locking devices
or ties, or at least an "octopus strap".
2.14 It is recommended that a roll bar be fitted into the cockpit
for extra safety at speed events. This will be of even greater safety
value on the road. Several types are available.
2.15 To increase driver comfort, you may find it advantageous to
raise the front of the seat about 1.5". This tilts the seat back so
your shoulders are further away from the steering wheel, and increases
your thigh support. Wedges or spacers can be inserted under the seat
front mounting bolts. Alternatively, the pivot point (where the back
of the seat is hinged) could be re-fabricated and raised about 1".
2.16 The belts holding down the lap section of the seat belts
should be removed and holes re-drilled in the floor so that the lap
section hangs straight down instead of pulling back. This will prevent
the lap section riding up and then you sliding out underneath it in
emergency braking. It is even more advantageous to do this when
fitting full harness seat bolts.
2.17 Smaller diameter steering wheels (12-13") can be fitted to
enable you to turn the wheel more quickly and easily. It also provides
more knee room between the seat edge and the wheel. However, the
effort to turn the wheel does increase slightly, and until you get
used to its quick responses on the open highway, it can feel quite
"twitchy".
2.18 On models Mk III onwards, the steering column can be shortened
by about 2.5" when used with a suitable steering wheel. When
shortening, do not forget to allow for finger clearance between the
wheel and the dash scuttle. The shortened column allows you to get
further away from the wheel, and so it becomes quicker and easier to
control the car.
2.19 For quicker, easier gear changes, the gear lever can be cut
down, or alternatively, a gear knob could be bought or modified so
that the lever goes right through it and almost out the top.
Alternatively again, bend the lever back.
2.20 In speed events it may be an advantage (especially with a
modified engine) to rotate the tachometer so that the orange and red
ranges are at the top for easy visibility. However, a tachometer is
only as good as its accuracy -- it may be wise to have yours checked
and reset if necessary.
2.21 Handbrakes can be converted to a "fly off" type (which
do not lock on unless the button is pressed down). Remove the
handbrake and replace the 'L' shaped ratchet catch with one that
you have made as a 'mirror image' of the existing one.
2.22 Standard width conventional or worn radial tyres fitted to the
rear of the car are an advantage for bitumen motorkhanas - in order to
encourage the car to oversteer quickly.
2.23 Wider wheels can be fitted to increase road handling and also
comfort. Wider 4.5" rims can replace the standard 3.5" ones on all
disc (solid) wheel models usually with no body fouling; and they do
not look like widened wheels to other people. Always leave the inside
offset of the rim the same as the standard wheels. For most cars, 6"
rims will be too wide for the suspension and bodywork. For very wide
rims for racing tyres etc. (over 6"), widen the front wheels inward
about 1" to maintain steering stability. The outer corner of the nut
on the steering ball joint will need to be filed back 0.25" for wheel
clearance.
2.24 When wider disc wheels are to be fitted to the car, care
should be taken in selecting the best centres for the wheels. The
extra strain of wider rims can cause a previously adequate centre of a
standard wheel to crack. The available centres in order of increasing
strength are: A30, Mk 1, Mk 2, Mk 2A/3, A40 Farina, Moke (13" x 4.5"),
Minor 1000 (14"), Lancer/Major Series 1 (14") and Lancer/Major Series
2 (14"). With the Minor/Lancer 14" wheels, have them turned down to
13" when the wide rims are fitted and be sure to use their wheel nuts
as they have a different angled tapered seat.
2.25 In order for the car to brake and handle properly, you must
have good tyres. It pays to spend a little more and buy top quality
tyres - because there are only four small areas of rubber contact
between you and the road, and you may need every bit to tenaciously
grip the road in an emergency.
2.26 When buying new tyres, fit the smallest recommended tyre size
to your rims - aim for straight, non-bulging side walls for better
handling e.g. 145x13 for standard 3.5" rims.
2.27 When wide wheels and tyres are fitted, remember that the
rolling circumference is also increased. This means that as well as
the car being slightly higher off the road, the overall diff ratio is
increased. For example, a 165 tyre on a 5" rim and using a lower
speed 4.5 diff, has the same effective ratio (and therefore the same
acceleration and top speed) as a standard 4.2 diff with standard
tyres.
2.28 A lower diff ratio from an A30 etc., can often increase
performances in motorkhanas and speed events. Possible diffs are: 5.3,
5.1, 4.9, 4.5, 4.2 (Sprite), 3.9 (1275 Midget), and 3.7 (Refer to the
article "Know the DIFFerence", Goblins Gazette, July 1977)
2.29 On Mk 1s and 2s, the 7" front drum brakes can easily be
replaced by the 8" A40 Farina brakes. The whole assembly bolts
straight onto the stub axle. This gives about a 50% increase in
braking area - which results in brakes that won't ever fade and enable
you to brake harder. However, they do give a harder foot pedal.
Alternatively, Mk 2A or 3 disk brakes and master cylinder assemblies,
which are more expensive, can easily be fitted.
2.30 If your engine and suspension ever become so well developed
that your brakes become less effective, then you may decide to graft
Cortina 9" disc brakes onto Sprite or A30 king pins; these brakes
are extremely effective, but they do increase the unsprung weight a
lot. Also, for clearance on the callipers, Lancer/Major wheel centres
or mag wheels must be used. When they are fitted, Lancer/Major 8"
rear brakes should also be fitted. These bolt straight on, but the
hydraulic lines and handbrake linkages must be altered slightly.
2.31 Brake fluid absorbs water and so this can eventually lead to
wheel brake cylinders rusting up, or at least destroying the
'rubber' seals. It is a good policy then, to change all your
brake fluid, say, once a year. When did you last change all your
brake fluid? (Note: today's silicone- based brake fluid do not
absorb water -- Ed)
2.32 When suspension and/or engine modifications are made, it may
be desirable to fit solid wheel spacers to the front and/or rear, to
alter the handling. For example, when disc brake assemblies are fitted
to Mk 1s and 2s they have a wider front track, and this may affect
handling on well developed cars. Spacers could then be fitted to the
rear. When spacers up to about 0.5" thick are used, mini-moke or
Cooper S longer wheel studs should be used. Instead of 0.5" spacers on
the rear, standard Cooper S thick brake drums or even "Minifin" S
drums could be fitted.
2.33 For longer wheel bearing life (especially where wide wheels
are fitted), tapered wheel bearings SKF 30303 and 30205, can be fitted
to the front, and the distance piece is left out from between the
bearings. Spacers of normal washer thickness may need to be fitted
between the hub and the disc, so that the disc runs in the centre of
the calliper. These bearings are many times stronger, last longer,
and are adjustable for wear.
2.34 Stronger wheel bearings can be fitted to the rear hubs also -
SKF 207Z (NR), 207ZZ (with dust excluders), or fully sealed bearings
6207VVCMAV2 (NSK) can be fitted (these allow less oil to be run in the
diff. and so less oil will escape the oil seals and onto the brake
linings when cornering very hard).
2.35 The Sprite front suspension is poorly designed. When one part
wears, it quickly causes other parts to wear - leading to eventual
breakdown of something - usually "shockers". So check for wear and
replace all worn parts. A worn front end will greatly upset the car's
handling.
2.36 A front stabiliser bar (anti-roll bar) prevents a lot of body
roll when cornering, keeps the car "sitting flatter", helps prevent
the rear wheels lifting, and stops rear-end sideways "patter".
Possible bars that could be fitted - in order of increasing thickness:
Assassin, Midget, Triumph Herald, Simca Aronde.
2.37 Almost all sprites over their lifetime have sagged on their
springs, so it may well be inadvisable to further lower the car.
However, "lowering" does increase the handling ability of a car by
lowering the centre of gravity. The front can be lowered in 4 ways:
(1) fit spacers between the "witches hat" (that the spring
sits on) and the lower wishbone;
(2) cut a coil from the end of the spring (this also hardens
the spring rate);
(3) have the springs re-tempered lower;
(4) have new lower (and harder) springs made.
The rear of Mk 1s and 2s can be lowered by putting wedges
between the springs and the bodywork plate and then re-tightening the
U-bolt clamps. For Mk3 to Midget rear ends: fit metal lowering blocks
(about 1.5") between axle housing and springs and fit longer
U-bolts. Alternatively, all models can have the springs re-tempered
lower, or new lower (and harder) springs can be made, or again, the
rear spring eyelets can be reversed.
2.38 Harder springs (and/or shockers) can be fitted (if desired)
for speed events. These prevent excessive body roll. Front coil
springs can be hardened (and lowered) by cutting one coil off each
spring (or more if desired). This prevents the front of the car
dipping severely under hard braking. Alternatively, new thicker,
harder front and rear springs can be made up. Rear springs of Mk 3s to
Midget can have their leaves replaced by Morris Minor or A30 spring
leaves to harden them. Harder shockers should be fitted with or
without these harder springs for better handling at speed events.
2.39 If the rear suspension has sagged or been lowered, it may be
found that a rear wheel lifts off and spins under hard cornering. This
happens because there is less axle movement than when new and
standard. On Mk 1s, 2s, and 2As, this can be largely overcome by
cutting the rubber "bump-stops" in half (to allow more axle travel)
and by undoing the "drop straps" on the axle. This happens less on
later models, but when it does occur, it usually means the car must be
raised (since there is less bump-rubber that can be removed).
2.40 A well-thought-out and very strongly mounted panhard rod
(fixed from one side of the rear axle housing to the body on the other
side) will prevent the considerable sideways movement of the rear end
- especially on Mk 3s onwards. This gives more precise handling,
better cornering ability and a quicker steering response.
2.41 Rear axle overhead links (as fitted on Mk 1s to 2As), or lower
track rods, when fitted to the later models, prevent axle hop or
spring wind- up when accelerating hard from a standing start.
2.42 Sprite axles seem to break fairly easily. When one breaks,
replace both, because the other one will usually break soon after.
Keep it in the boot as a spare. (Carry a tube of "Silastic" to use for
gaskets as well.)
2.43 A method of preventing axles from breaking is to have them
"turned down" all along their length from the spline to the flange.
Turn them down so that the diameter is the same as the distance
between the bottoms of two opposite "valleys" of the splines. This
means that instead of the twisting pressure only acting across the
narrow section of the spline (and eventually causing it to break off
there inside the diff), this twisting pressure will be evenly
distributed along the whole length of the axle, and so it will not
break inside the diff (or anywhere else).
2.44 For more torque and horsepower, the early model engines and
gearboxes could be replaced by 1098 or 1275 engines and gearboxes with
no other modifications needed. However, if a 1098 or 1275 engine is
fitted to a Mk 1 or 2 gearbox, the bell-housing must be ground out to
clear the new clutch. Also, the carbon thrust and clutch release fork
to suit the engine must be fitted to the bell-housing in order to get
a fully operational clutch. As well as this, the 1275 diaphragm clutch
must use the 1" bore clutch slave cylinder as fitted to the 1275
engines - for a correctly operating and long-lasting clutch. (The 1275
split master cylinder set-up should also be fitted - or the hydraulic
line adaptors used.)
2.45 Engine modifications must be considered carefully. Never just
modify the engine without thinking about what else must be done to the
car at the same time, to make it perform safely and as you want it to.
Don't just modify a couple of parts of an engine without
investigating what else should be modified in order to get an
integrated, smooth and reliably running whole engine.
Recognise the weak parts of an engine's design and work
within their limits, or modify and upgrade them.
Possible engine modifications are many and varied and would
take to long to list for all the special requirements that every
individual has. The best idea is to ask all the "old hands" in the
club for their suggestions and then develop an engine from all the
suggestions that suit you.
For suggestions on camshaft grinds, refer to the article on
"How to Choose a Cam", Goblins Gazette, September 1977.
Similarly, when tuning Weber carburettors, refer to the
article "Are you having trouble tuning your Weber?", Goblins Gazette,
July 1977.
John Fowler, 1979
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