C - SpridgetGuru.com

FOR THE
MIDGET
AND SPRITE
948 e,c,
-
-
(.
- -- - I -----~-,------,
~
-
~
--, -
.".
"•
Iss ued by:
BRITiSH
LEYLAND
SPECIAL TU NING
DEPART MENT
ABINGDDN -DN -THAMES • BER KSHI RE·
ENGLAND
C- AK D 1D21C
.•
ENGI~~
NO PREFIX
Capacity
B.H.P.
Torque
Bore
Stroke
Compression ratio
Combustion chamber vol.
Oversize pistons available
geG
9C
(where
57·87 cu. ins. (948cc)
43 b.h.. p. at 5,,200
52 Ibs.ft. at 3,300 rvpvn,
2·478 in. (62·~1
3·00 in. (76.2%"
8·3,;].
differc~t
to
46·4 b.h.p. ® 5,500 r.p.m.
52·81bs/ft ® 3,000 r.p.m.
9·0:1
26·1cc
24·5ee
+.010,·020,.030,.040 in.
(+.254".508,.762.1.016%)
Firing order
Oil pressure
(normal) running
(normal) idling
Connecting rod side clearance
Connecting rod diameteral clearance
Main bearing type
Standard Journal diameter
Minimum regrind diameter
Main bea~ing clearance
Camshaft bearing type
Camshaft bearing clearance
front
Cent:::.-e & rear
Camshaft end float
Valve ti~ing marking
Exhaust vAlve:
Head c.iameter
stem diameter
Ln l e-; ve Ive .
Head diameter
Stem diameter
Valve seat angle
THlING
Inlet valve opens
Inlet valve closes
Exhaus-t va.lve opens
Exh3list valve closes
,Valve clearance for timing
valve runrU-~g clearance
Valve lift
VALVE SPRINGS
Fr-ee ler.gth
Lead fitted
Load at full lift
1,3,4,2
60 p.s.i. (4.2 kg/sq.cm.)
15 p.s_.i. (l.05 kg/sq.cm.) min
·008 in.-·012 in.
(.2C3-.30~)
·001 in.-·0025 in. (.025-.063%)
3 Steel-bac::ked Lead. indium
1·7505-1·751 in
(44.463-44.47~)
1·7305-1·731 in.(43.955-43.96~)
·0005 -.-002 in. (·.0127 - .0508 %)
Front-steel-backed white metal.
Centre & rear-direct
All steel backed
.001--002 in.
(.0254-.0SJ~)
• 00125-· 00275in. (·032-· 07 %)
·003 - .007 Ln , (,0762-· 178%0)
Adjoining gear teeth marked
wru te
me t c ;,
All as
f ront.
1·00 ino< (25.4%1
0·2788-0·2793 in. (7.C81-7.094~)
1·094 in (27.~)
1·151"
0-2793 - 0.2798 in. (7.094-7.107 %1
0
45
o
5
before T.D.C.
0
45 after 8.D.C.
o
40 before B.D.C.
100 after T.D.C.
0.019 in (.41l)l1
0·012 in (.3,%) cold
0·28 in (7.14"''')
1·75 J.n.
1·296 in
52 Ibs/sq. J.n.
84 Lbsv'eq s Ln,
-
1 -
,
_0
-
45°
5,1"
n°
·029"
• C15" (compeLi:.io:;)
. 312"
Outer
Inner
1·E72 in.
1· 75 in.
, .
"- • J. ';' IT.•
1· 296 Lr, ,
52 1bs/sq.ir.. 13·': Ibs!sq.i:,.
~~
88
Ibs/sq.i~.
31 1bs/sa.in.
IGNITION
Type
Distributor ~ype
Co~tact breaker gap
Static settinc
Sparking plug type
Sparking plug gap
CA?ACITIES
Cooling s ys t.em
F'ue I tank
Gec.rbox
ReeL" axle
EYlgine Sump
FUEL SYSTEM
Fuel delivery
Cerburetter type
Needle (norrna'l )
CLUTCH
Thickness of linings
NUTber of springs
Pedcl free ITovement
9C
9CG
Lucas 12 volt coil LA 12
Lucas DM2 PH4
0·014-·016 in. (·356-40$%)
5° before T.D.C.
4 0 -Defore T. D. C.
Champidn N5
0.024-0.C2Q:in. (.6196-.n6~)
-, i
10 pints (5· 68 j.Lt.cesr, '12 U.5. pints)
6 gallons (27-3 -Lt t res , -rz-.·z U.S. gallons)
2t pints (1·325 litres, 2"·B07 uvs , pints)
Ii pints (1·0 litres, 2.1 u.s. pints)
6 pints + 1 pint for filter
', '
A.C. Sphinx 'Y' Type, Me c ha ni c a l
Two S.U. H.I. Semi down draught
Two HS2
GG
Y3
tin.
(3-175 %)
6 (YellO'...· and Dark Green),
0·156 in (3.969%)
GEA...l:t.BOX
Type
Gear ratios:
First
Second
'l'bird
Top
Reverse
Layshaft bearing
REAR SPRINGS
I'ype
of leaves
FRONT SUSPENSION
N~er
Synchromesh on 2nd" 3rd and top
3·627
2·374
1· 412
,
,
1·0
1
,
•
-
3- 2 • 1
1·916 • 1
1·36 :. ,1
1
1
1
-1
40114 •
1.G
4·664 •- 1
23 needle rollers
-t
•
15
&
Drum diameter
Total friction area
Shoe Lining width
Pedal Free Movement
wishbones
9·4 in. (23.8',%)
6·625 in. (16.85 cm) @ 750 Ibs. (340 kilos)
7
271 Ibs.!in. (19
Parallel to
kg!e~)
iin. (0 to
3.17P~)
3°
1°
6+°
BRA..KES
nake
1
elliptic
fndependent , .ccd.I spr.mqs
Spring :
Free lenath
Fi t.tec lengtr,
N~Tber of working coils
Spring rate
Track toe in
~
-~2S
r or ang 1 e
Camber angle
S,d vel pin inclination
-
Lockheed hydraulic
7 ins.
67.5 sqc Ln,
in.
It
·156 in
.','
(435· 37 sq. em. )
(3.969~)
2
-
9C
<KG
Be t r e r v type
BT 7A , 1 2 v o lt
Gen
re tor
' •e
• -<=-
Lucas C39 OV2 wi t h t acho dr i ve
1 , 0 50 to 1 , 200 r . p. m.
13· 5 vo l t s 19 amps .
-~
Cut ting in s peed
Ma x i ;1"'.lm ou t pu t
S ta ~ t i ~g motor : y pe
Lucas M35 Gl
Cor-t r o l box type
Luc a s RB 106 2
WHEE: · ;''':-./0 TYRE DATA
Ty ....:. <:.;.... 'C. &'>
-- _
~ · 20
~-
Pr-e s sure s : f ron t
re e.:::Wh e '2 1 -; ype
- 13 Tube les s
:8
Ib s ./ sq . ~n .
~O
Ibs . / s q . ~ n .
2
(1 - 2 7 kg . ::m )
2
( 1 ·4 1 k g · e m )
1 3 x 3. 5D s t ee l d i s c , 4 s tud f ixi ng
TORQUE S!?ANNER DATA
Cy l in d e ~
he ad
Cop~ ec t i ng
rod
s t~d
nuts
~ig
40 lb/ f t .
(5 ·5 k g/m)
end bol ts 35 lb/ f t . ( 4 · 8 kg/m )
Mai ~
bea r i ng s e t s c r e ws
F l y .·!h e e l set s c r s v.. s
6 0 Ib/ f t . (8 ·3 k g / m)
4 0 I b/f L (5 . 5 kg/m)
Rock c ~
br acke t nut s
Gud ~ e c ~ Pi n C l a~p scr ews
GENERAL DI~ S I ON S
25 I b/f t . ( 3· 4 kg/ m)
2S Ib/ft . (3 . 4 kg/ ml
Overa ll l eng t h
11 ft . 51-i n . (3·49
Whe e l=.:=.se
5 f t . 9 in . ( 2 ·0 3 m)
5 .i.n , (0 · 1 3 rr.)
4 f t . 5 in . (1 · 35 m)
3 f t . 9i i n . ( 1· 16 m)
Min ~~ ~m
g round c l ear ance
Ove r a l l "oJid t h
T r- ec k
( f r ont )
3
~t .
at
m)
i~
( 1· 14 m)
31 f t . 6 in (9 . 60 m)
'rr-e cc :: rea r)
'ru rruno circ l e
..._ ...
Aocr
c .x. i_ ...<0"".
ma c e k e_ r_ Lb s.r oe we ight 1 3 c ....-t ,
~
( 6EC k g ) .
WA RNI :~G
The se ca r s have had a cons ider able amount of us e b y now a ~d i t i s i~ ~cr t a nt
t o en5 ~ r e tha t ~h e ~hD l e o f t he car i s in s afe anc sati s f actor y co ndi t io~ Cc£o rp.
ca rryi ng cut a ~y ~uning .
F ~ ll
informct ion on t h e c orr ect maintenance a nd
re pa~r
t.at r.ed a.r: wo r k shop Manu al P a rt No. AKD 4884 01k. . I Sprit e!
I I / II I Spr i t e )
~ r. j
Mk . I / I I Mi dg et) .
-
3 -
1
o f t hes e cc r s i s c ono r AKD 4021)) (:.1).; .
Introduced in 1958 with t.wa.n Ii" s.u. Ce.rburet.t.er-s the Sprite Mk.I
utilised compon~nts from the then current A35 and was identified by the
engine prefix 9C.
In 1961 the body wa s restyled and commonised with an MG Midget series
(Sprite ?&.II - VQdget Mk.IJ. The power unit was uprated in this application ~ith a slightly better camshaft (AEA 630) using three camshaft bearings,
flat top pistons and larger inlet valves in an improved cylinder head. Twin
Ii" s.u. carburetters were standard. The gearbox was also improved wi t h
closer ratios and gears on needle rollers in place of bushes, all identified
by the englne prefix 9CG.
ENGINE TUNING 9C UNITS
An increase of some 2 B.H.P. can be obtained by general attention to
the cylinder head and port polishing.
Lightly grind and polish the exhaust
and inlet ports throughout.
They should not be ground out S0 heavily that
the shape or' valve choke diameters are impaired.
Match up the exhaust rraDifold ports with the cylinder head ports by
qr i.no i.r.o ,
Grine. out the inlet bore
the rnand fc Lc to It" diameter at
the c yl Lnder- head face by g.:-inding out right through to this diameter to
match the carburetter bore, and then polish.
0=
Do not grinc out the co~bustion spaces as these are already quite clean
and partly machined! but remove any frazes and lightly polish all over. A~y
enlarge~ent araunG the combustion walls nay cause the cylinder head gasket to
oveLlap and destroy the efficiency of the seal.
Also the compression retia
will be lowercd and the tuninc will be ineffective.
A further increase can be obtained by alteration to the irclet/exhaust
ports.
Grind cut and enlarge at the inlet port neck.
Make up a sheet-metal terrplate to the dimensions given in Fig. 1 and
fQstc~ it to a long bolt so that it may be used as a gauge when grinding
out the inlet ports.
Be very careful to grin6 the inlet port throat central,be~~een the push
rod holes, as the wa Ll. left is only ·086" thick. Ease off the port by gri::1cr.nq at the valve guide boss 2.Ld the opposite port 'd2.11 bend as depicted ir. Fig.
2.
Erl2.rge the ek~aust ports at the ber.ds by grinclng at the valve guide
boss aDa the opposite port ~all as sho~~ in Fig. 3.
WarD2-liO When carrying out aj t.er-atd.ons to the shape of the valve ports, t.t:e
responsibility for any damage that may occur must rest with the owne r or the
person authorising the alteration.
A~ternatively
a polished and modified cylinder head can be purchased
includir.g the above modifications, under Part No. C-AHT 87.
This head ~ill
also increase the compressicr: ratio to 9:1, and atreecy r t t tec wt th new ve rves
and """'1-·-','"- ,,'
spr-I nos
,-",
. ,-'
."_.'
car-bure t t s r needles C3G, or
B.T.D .C.
- 4 -
Gr,)
v.t thout ai::- cr earner-s ,
Fla t t op pi s tons 12A 18 7 wil l give 9 · 3 : 1 coocpress ion
0
head modi f i ed as above .
Se t i gni t i on t o 3 B.T . D. C.
~~ th
t he
s t a~c = ~d
vmen fit t ed wit h t he modi f ied head C- AHT 8 7 t he compr e ss ion r a t i o
inc r ea s e t o 10· 6 : 1 .
Set i gn i t i on appro ximat e l y 2° B. T. D. C.
~ i1 1
A polis hed and modifi ed ve rsi on o f t h e l a rger va l ve 9CG head C- AHT 90
co ul d be f itted wi t h the f la t top pi s ton s , compres s i on would b e 9 · 7: 1.
I g ~ i t i o n a nd car bu r e t t e r need l es a s above .
Af t e r c ar r y ing out thE e ar lier stages o f tune,
c an be ob t ainec by f i tti ng the f o l l o wi ng p arts :-
eddi t io~a l
i rnpro v e ~e ~t s
Va l ve s pring s
8 of f
Par t No . C- 2A
Camsha f t
Pa rt No .
SSG
o
Timi ng , I n l et; open s 16 B. T.D .C . , c l os es 56° A.B . D. C
o
E x..l)au ~ t
opens 51 B.B. D.C " c loses 21° A. T . D. C
Va l ve l i f t - · 312 i n. ( 7· 94%)
Di s t r i bu tor (us e with c amshaf t BSG 229 )
Par t Nc . ~- 2 7H 7766
Ret a in the s t a tic ig~ition at 1
0
B. T. D. C. i rre s pect i ve of c y l i nder
head .
Ca r bu r e t ter needles GG Part No . AUD 1 211 vri ~h a ir
GM Par t No . AUD 1217 less a i r
Over 9· 5 : 1 compr e s sion use t he r i cher nee d l e
If t he i n l et manifold i s po l i s hed out t o
(Std . on 9CG ) ~he ne edl e s ~ou l d be
( Ri c her )
~8
acce ~ t
c l ea~ er5
c l E a~e r 5
Part No. AUD 1149 .
t he I t" H5 2
c a rbuc ~ -::t e J::'s
V3 Pa r t No . AUD l ~ l l
V2 Pa r t No . ADD 141J
USE cyl incer he ad ga sk e t C- AEA 64 7 in a l l c a s e s of ra isec c omp ress ~ o~
e x= e p~ wi t h r ac e cyl inde r ~ e ad C- AHT 22 2 on whi ch gas ke t C -F~~ 188 s hou l d
be us ed .
ENGI ~ E
TUNI NG :JCG
Thi s power
and port sizes .
~~ i t
h as
2
cylinder he ad wi t h i nc r e a sed inl e t va l ve
di ~~ e te ~
C- AHT 90 i s a po l i s hen and mod i f i ed v ers i o~ ~va i labl e f o r imme di at e r e placement , ~n i ch again i s comp l e te wi th va l ve s , s p r~ r.g s ar~ ccl l e t s e t c .
As the f l :l:' top pi s t ons are s tan da rd t o t hi s ~o d e l corrpres s i on wi ~ l b e
i nc r ec s ed to 9 · 7 : 1 .
S t a ti c i gnition should b e 2° 3 . T.D .C. ~i th s ta~ d2rd
needl e s .
As t his rrode l has AEA 311 and AEA 401 va l ve spr i ngs as s t anda rd ~r. ~ r eV
r~~ e is grea t e r than 9C uni t s (SEE SPECIAL IT E~5 Val ve Spr ings ), L~ e c a~shaft
i s AEP. 6 30 wi t h i ncre a sed l i f t and e xhaus t va l v e Fe r i od (Se e Da t a ) .
Camsha f t SSG 229 and Distribu t or C- 27H 7766 (de t a i l s cDCve ) wi l l pr ovi de
i r.cr ea sed po~e~ and r . p . m.
AT THIS POI]\,T THE ENGINE SPECI FI CP.TION BECOnES SI MI U .R
~~ U ST
SYSTEM
A special tuned exha us t sys tem is avai l ab l e whi c h wil l ,g i ve an incr e2 s e
of scme 2 t o 3 B.H.P . acc o r di ng t o the tuni n g condi tion i t i s u~ed wi t h . I t
may be lised with any t uning cond i tion .
The system consis ts o f :
F ~on t Manifold (inc l uc e s c l i p C- k4A 54 50)
pipe
Si l enc e r a s s e mbl y (includi ng c l ip AHA 5450 )
E~~aust
Pa r t No .
e - AHA 5448
C-~. 5449
C- ARA ' 1 35
F o" =ac i ng a ppl ication s u s i ng l a r ge c a r bur e t t e r s , l a r ge va lve he ads , e tc .
the ms xi mum ext r ac t o r man i fo l d C-AHT 11 should be fi t t ed .
VALVE SPRINGS
( a)
The 9C un i t wi t h s t and ar d cams h a f t and s t and a r d v a l ve s prings wil l have
va l ve -c r a s h occur at 6 , 100/6 ,300 r .p .m .
(b )
,men
(c )
The competi ~ i on c ams h a ~ t Part No . SSG 22 9 can also b e used wi th t he
s tanda r d va l v e s p rings , wh en valve b ounce wi l l oc cu r at 6 , 300 t o 6 ,400 .
(d)
The va l ve Sear and dri ,e e r e saf e ly stres s ed t o mai ntain t he above
~o rrd i t ion s ( a) , ( b ) a nc ( c ) .
I f : howeve r , f o r very special competition
p~pos es . i t i s des i~ed to r ai s e t he valve bo~~ce pos i t i or. t o 6 ,70 0 r . p. m.
i t can be done b y us i ng outer va l ve s pri ng s Pa r t No . C- 2A ~5 0 and f i t t i ng
e xt r a i nne = va l ve s pring s Pa r t No . AEA 401 . New t o p and bo t t om s pr i ng
cel l ars AEA ~0 2 and C- AEA 4 32 mus t be f i t ted f or t h i s cond i t i on .
Tc
fi t the b o ~ tom co l l ar C-AEA 432 i t will be ne ce s s ary t o s pot f ace the
s 8 a l l c a s t rec e s s e s on the top of t he cyl i nde r head , a round the valve
g~ i d e s t o a diamete r of ·8 75 m. ( 2 2 . 22 %) in or de r tha t t he co l l ar s
~ i l l drop in and s ea t s~~ar e ly .
The dep t h of t he s pot f ace s hou l d be
3/ 32 i n . (2 ·38 %) b e l o~ t he ou t e r va l ve s pr i ng f ace .
(e )
The va lve bounc e pos iti on can b e f urthe r r aise= t o 7,OCO =. p. m. i f t he
e xt ra i nne = valve s pric,gs and co lla rs f itt ed as expla i nee i n ' d' wi th
t he standa rd outer va lve spr i ng A~~ 311.
us i ng t he compe t i tion c amsha f t Pa r t No . SeG 229 and special va lve
s p r i ng C- 2A 950, va lve bounce will a l so occur ~t a ppr o ximate ly 6 ,100
~ o 6,300 r . p .m .
This a rra ngement using
stanc~r d 9CG ar r angemen t .
bo~ tom
co l l : r AEA 4 03 (not C- AEA 432) i s the
I t is advi sed t h at t he 2 c~ ve va l ve spring re-ar rangements be used only
f o r s pec i a l compe ti t ion pu r ?~ s es , i f us ed for 2v erydcy c ond itions the e~g i ~e
part s rea y ha ve a s ho r t e r se~~ice l i f t. The valve s prings wi l l no t neces s c ri ly
gi ve ~, i ncreas e in b rake-h ~r5e- powe r , c ut will extend t he sa~e ho rs e-po ~er
u p to ~ highe~ =. p. m.
Thi3 i s someti~e s usefu l irr enabling a l owe r r e ar axl e
r a t i o t o be reta i ned , and still main t ain t he same ~a xi mum speed . wit h i nc r e a s e d
power of acce l er a t i o n.
Standar d or c ompet i t i G ~ c amshaf t s may b e u s e d , the valve gear s t r e s se s
b e i ~g lea st wi t~ t he compe t i t i on c ams h aft s .
- 6 -
VA.: ;vt. GEAR
wn e n pr e pa r i ng units f o r competi t i o n t he i deal r ocke r g e a r t o use is
f ~c~ t he Coope ~ ' 5' s e r i es .
Rocker ] 2G 1221 i~ ligh t e r wi t h gr e e t er s t rengtt
be t. requ i r e s ne w adjus t L"1g s c r e w AD; 16 7 and Iockr.u t; n ,iN 6CS: .
Sf-ef t AEG 399
has t he l oc a ~ i ng hol e ~~v ed i n o n e pil lar requi =ing a d ri l l e d p i l la r f o~ the
o i l ~cy .dis Fen se fti t h one ~ tar.dard pi l l a r . The l o c a ting scr e w 12G 19 26 pi l la r
$ ho~ l c ~e I.c v eC to co i nc i de ~ith t he ~ ~ a f t l oca t~on .
The r ockers s hould be
s paced by us ing di s t ance t ubes C- AEG 392 i n p lace o f t he co i l s pring s .
EXHA.lJST VALVE
whe-n r e p l aci r.g va l ve s in s t anda r d 9C a nd 9CG he ad o r C- AHT 87 and C-AHT 90
c y l i ~ c c r he ~ d s , us e ONLY AEA 400, KE 965 ' S t e l l i t e ' f ac e d .
DUP LEX 'l'I MIKG GEARS
The increased s t r e s s es c r ea t e d b y hig her l i f t c a ms , s t ronge r v a l ve
s pr i ngs p t e • . r educe s the wo~k i ng l if e of t he sta ndard s ing : e r ow ti mL~g
ch~ i" .
Fo ~ e l l compe t i t ion o r hi ~hl y t uned ~~~ t s the Dupl ex cha ~~ s r.ould
be fi t t ed us i ng Kit C- AJJ 3325, ~h ic h cont a i ns a l l neces s a ry pa rts a ne
f i ~~ i ng
in s t ~c t ions _
CRANKSHAFTS
CcrnDet ~ ~ i on
t~t ter ma ter ~ c l
been av ail ~ l e
and C- AEA 46 1 Nit r i ded .
c rapk 5~o fts
~a ve
previ o~ sl y
C- AEA 4C6
C-AEA 461 had eight s~~ d ~l~n~e an d rec~i ~ ed t he c e nt r e mUkn
to c l ea r the webs .
St ock s of these type s a r e now e xha us ted .
i~
~ccP~~r. q
The Le t e s t, c ompe t .L c i .cr, c r- enk ahef t; C- AEA 792 i s i n i mproved mate r i a l a nd
Tc; f t r-i ded , it is a di r ec t r e p l ac e men t of the stand a r d ":ypes or C- AEA 406 .
BALANCI NG
Whe r e un ::' t s a r e pre pa r ed f o r ma xi mum output; i t is es s e nt i a l t hat the
r ot e t inq es s err.o kLes a r e f u l l y b a l anced i.e . c r ank s ha r t , f Lywhe.e I and c lutc h
St andar d c r~ rksh afts c ~ ~ t hen s a =e ~o 6 ,5CO cFm the C - A ~. 7S2
may exc e ed 7 ,~OO r pm while the F/ J C- AEA 46 1 ha s e xc eeded 8 , 500 rpm.
Re~ ~ound c rar~sh~:ts a re cot recow~e~~ ec fo r f~ rf~ ~nce wo ~k . but if :'0
e l t e rna tiv~ i ~ dvai 1a~ le t he =r arkshart ~s t be =e-b a l a nced aft e~a rc $ .
Ni t r Ldod a h a f t,o may a ccept · 0 1 0" u nde r oLze a nd t uf t rided · 0 20" unc e r s I ze
~~lhcut prc = ~ s sir. ~ ugain . but THIS CAJ~ NEVER BE DEFI NITE.
c5 s ~~~ l y .
The crenk shej t alene does no t limi t rpm ( as s uming s u i t abl e cam , va l ve
so=i ng , ca rbc~ e t ter a r r cr,gement s . et=.) .
Th e s t a ndard c l a~p bo l t t y pe
cop~ ec t i ng r e ds are ~ r.sui tabl e f o~ s E riou~ co~pe t it ion ~o rk . whe r e f~l ~ y
floa ting gudg ~o n p ins ar~ rods a r e ~c h be t t e r .
- ", -
PISTONS
~J D
RODS
Fo r compe ti t i on u se t he engine capacit y can be i ncr ea s ed t o t ake
adv a ~to g e of t he c la ss l i mit s ( l OOOc c) .
Us e he ad gask e t C-AEA 647 .
By bo ring the block · 06 5" o ver s i z e to 2 · 54 3" t he Coope r 998cc pis t ol' s .
;.2A 6 74 c an be ac commoda t e d together with r ods l 2G 12 3 & 126.
Capac i t y
t hen be 998c c , inc r e as ing low s peed torque .
Wi t h cyli nde r he ads
poli sh~c bu t no t reduced i n c epac i t y t he compr ess i cr. r a t i os ~~ ul d be 10 : 1
and 9 ·4 :1 fo r 9C a nd 9CG head s r espec tive l y.
w~u l d
C- AHT 87 cy l inde r h e 3d , compression would be 11 · 6: 1
With C- AHT 90 cyl inder he ad , comp ression would be 10·4 : 1
Wi~h
Ai ce r netuve r y f or a f e l l race powe r unit , usir.g the 2 · 54 3" Bore . F"i t
pistons set C- fJJ 4039 wi tt c on- r od s et C- AJ J 4035 . t he s e pi s t ons wi l l not
f i t any ct ~ er rod s .
t he s E pa rt s f itt ed t h e b a s i c s pec i f i c a t i on i s very c lose t o
Formul a J uni or a~c it i s s~g g e s t e d tha t on l y the ' r a c e ' cy linc er he ad
C- AHT 222 i s used wi t h ga ske t C- AHT 188 .
Wi t~
Thi E ha s g r e a t ly imp rov ed port s i zes a nd l a r ge r va l ve s , ~h e compr e s s i on
r at io ~o~ l d be 1 2 : 1 nominal 2nd la rg e~ c a rbure t te ~ s wou l d be ceou i red .
CAF.BURET?ERS
I n r ece t une wi t .h l i gh t e ned fl ywhee l ( s ee bel o~ ) f ully ba l anc ed as s errb l y ,
c - xsrr 2 22 he ad and t he r ac e c ams haf t s C- P-.EP. 731 c s: C- AEA 6 48 , l a r ge r I t " s . U.
H4 c a rb~ :- e tt e rs s hoe l d be fitted .
Us e i~l e t ma ni =c l d l2G 5E3 ~i t h p l ug ADP
210 an d wa s he r 23 36 64 .
Fit he a t shi e ld l 2G 1 50 9 i f de s i r ed .
1-1" S . U. Carburet t ers ar e ava il ab l e a s a pa i r C- AUD 194 t oge ther wi t b
Kit C-AJ J 3304 .
Remov e t he standar d c arbu r e t t e rs . but be r ors ·
remo v ~n g t he hea t shi e l d , us e one of t he in s ulat o r s Part No . AHH 3713 pr ovide d i ~ t he I n s t a l l a ti on Ki t C- AJJ 3304 t o mark out t he l a rge ~ d i ame t e r
i nduc t~on ho les i n t he he at s hi eld a nd f i l e out t o su it .
Hole s s hould b e
d r i l l e d in t he lo~e ~ edge o f t ~e heat shield i rnme di c t e l y under t h e thro ~ t l e
re tu~ spr i ng l eve rs t o anchcr the s prir.g s .
T~o i~ su l a to r ~ f or each
c arbu ret ':er mus t be f itted ove r t he heat sh i e 1 d , ~o maint ai n i ndu c t i on pi pe
l e ng t ~ .
The bc ~e o f t he nani fol d i s already cha mfered t o ac cept l a rg e~
c a rb u~et ~e r s b u t c an, with advantage , ~e c l e aned a~d po l ished .
Instal ~ a t i on
Th e e xis ting conn ecti on ~ f or t he t h rot t l e ar.d mixt ure cat: e s ar e us ed .
but the ~ xture c abl e is c la~p ed t o the abut men t br acket Which , i n turn , i s
bal tee ~ o t he i r. s ~ j e of t he car burette = a i r clean er f lange s . ;~ c ai r cleaner s
ar e cal l ed f or bu t t rumpe t s C- AEA 48 5 ( s~e e l ) a r e avai l ab l e t o suit t h e s e
c a r bu r c t ters .
car b u r e t t er s s uppliec C- AUD 194 a r e f i t t ed ~i th No .6 r.eed les , b ~ t
some er.g~ne s may be be t t er s ~i ted by ~~ r.eed l es which a r e s l ig~':l y weak 2 ~
t h roug~o~ t the rar.ge .
Fo r conpet i t ion us e , CP4 n eed l e s may b e mor e s~i ~abl e .
T ~e
- 8 -
CAHSHAFT
C- AEA 731 camshaf t has t he f o l l owing s pec if i c a tion .
I n l et opens 24
0
E.T. D. C.
o
c l os e s 64 A.B .D . C.
Valve l if t O· 320 "
o
Exhaus t opens 59 B. B. D. C.
clo s e s 29° A. T. O. C.
Tappet c l e ara nce 0 ·01 5 "
C- AEA 648 c a ms ha f t t i ming i s a s f ol l ows :
o
I n let opens SO B.T. D.C.
c l o ses 70 o A. B. D. C.
Valve l ift 0 · 394 "
o
Exhaust opens 75 B. B.D . C.
o
c lo ses 35 A.T. D. C.
Tappet clea rance 0 · 015"
Ei t he r o f these camshafts wi l l extend the possibl e r e v r ange t o over
8 , 000 r .p.rn. wi t h gr ea t l y inc r eased power a t t h e e xpens e o f low s peed torque .
Wi t h C- AEA 648 cams haft t h e b l o c~ shou ld have a r ec e ss cut b ene ath t he
exhaus t; val v e head so t h a t at l ea s t · 060" c l ea r anc e r ema i ns when the va l ve
is on fu ll lif t .
This c le a~a nc e s hou l d always be c heck ed when bui l di ng a power unit
a high l ift camshaf t and/ o r a modi fi ed c y l i nder h ead •
~ i th
•
Use di stributor C- 27H 7766 wi t h
e~ther
of t h ese
c amshaf ~ s .
FLYW"HEEL
2i ghtenea fl ywhee l i s no l onger availabl e b u t. t h e spe =ial competition
It is
pu rpos e s f l ywhe e l s may be : i gh t ene d b y mac hi ni ng as s hown in Fig . 4 .
rrQst i mpor tan t ~ h at t he f lywhee l i s rebal anc ed a ft er t h e mac r.i ning opera ~i on .
A
M.A "T!"
BEARING CAP
At t hi s s t ag e it wou l d be pr uden t t o ' s t r a p ' ~he centr e ma i n beari ng cap
wi - h a s tee l billet at least -!" thick held b y l onge r studs and ny l oc nu t s i n
pIece of the stand a r d bo l ts .
Eng i ne s pri o r t o No . 9C/ U/H 1 168 had the r e ar
medn c ap d ri ll ed and pl ugged , which c aus ed some weak e ntnq so ehe s e s hou Ld be
avoi ded ..
CUJTG{
Compe t i t i cn clutches are no l onge r ava i lab l e =or the se mod els f .: .-oi.l t he
Fact o r y , but Bor g & Beck s ~ocki s ts c an suppl y t he :'o l l owinc nine s pr i ng
as sembl y . sui t able f o r mcs~ purpos e s :
-
Cover Assemb l y
Driv en Plat e
Space r s (8 )
Release P l -3 t e
1= the
c c~pe ~ i t1 on
Bor g & Beck Ref e.: .- enc e 50 333
4 5585/ 41
503 32
5034 5
1098 fly~heel l 2G 180 i s f i t t ec
c l u t c h f or 1098cc engine• •
la ~er
Co ve r As s e::lbly
Dr-i ven Pl a te
- 9 -
~t
wi l l a =c e Jt t he la t er
C- 3HA 4448
C- 3HA 4449
GEARBOX
No
as
gears are available for the 9C or 9CG gearboxes
chart the 9CG AEA 3021 had slightly c1ose~ ratios.
3~~ernative
sho~~ ~n
~he
nc~:.
but
The ~CS8/1275 gearbox 38G 374 is much stronger in const~~ction and easily
adapted to earlier models, standard ratios are as 9CG.
Use the later engine
back plate 12G 453 together with f1~vhee1 12G 180 and the 1098 clutch (see
clutch paragraph).
For co~petition use the Close Ratio Spur Gear Kit C-AJJ 3319 should be
fitted for greater strength, uSlng the latest layshaft 22G 673.
The spur gear ratios are
all cases.
Gear Rs t Los
ln the chart, top gear being direct lD
9C
1· 412
2· 374
3·627
Src
2nd
"s t
;:.XLE
sho~~
9CG
SPUR SURS
1·357
1·916
3· 2
1·255
1· l "- ").r;,<.
-"~o,
-
RATIO
Axles fitted after Austin Healey Sprite Car No. HAN7-2473l and ~~ Midget
GAN?-161S3 have changed pinion bearings and redesigned di=fe~en~ia1 asse~~ly.
wlll1e the co~p1ete differential assemblies are interchangeable between early and
late type axles, c.rowr whee I and par-Loris are r:ar Lnt er-chenoeeb Le, Lj Lus t r at.jon
'A' page ~3.
The differential cage ATA 7035 (iI1us. C) remolns unaltered and ALL axles
accept the Limited Slip Differential C-BTA 1226.
'.'
.vcc
orL
Ratio
Teeth
3· 727
3· 9
L/41
4- 22
4·55
4·875
S. 375
10::)/39
9/36
9/41
,P/
"
<. c
,,'
'I"~
s·
"<.:'>
3·727
"/Ll
3· 9
4_ 22
4· 55
lC/39
':'/33
,/Ll
C.W. & P.
Part "0.
"
Il1ustrction A
ATA I "- •
C-ATA 7354
ATA 7266
8G 7129
C4 no
ATA 7040
•
•
Carrier Assy.
Part No.
L j Lus t
r at.i.on B
AT!'.
ATA
ATA
ATA
ATA
ATA
7167
7167
7032
7032
7032
7032
BTA 535
BTA 1223
BTA
BTP.
o'q
B:A
3TA
549
549
549
549
~~LO
BTA
C-BTA
~' 5~
516
•
Differenti c 1
..~csy Part No.
~.
.
BTA
BTA
ATA
ATA
2A
ATA
551
1222
Riley 1·
7326
Up to I ,
7093
7230
7073 •
BTA 551
BTA 1222
BTA
:I,,'-;
Standard ..
"'..... e 1
"sr.
c
"
f-lo r-r-Ls
"'
o.
~on
van
A35 Van
Morris GPO veri
Later Ri Le'y 1. 5
Spr-L te!!"': coer. 0
From I ::0 0
ATA 7093
• Information only
~o longer available
} Sprite/Midget Cha~~e Point B~11~-24731/Gk~2-l6183
o Sprite/Midget Cha~ge Point By§S-65226/GAN4-77S91
DRIVE
SHP.FTS
As 31~ ~he Sprite/Midget axle shafts are i~terchange2b1e the latest shaft
3TA 806 (~or disc wheels) in impro~ed material can be fitte~ ~o earlier ~ypes.
C-BTA 94C is the strongest for ccn.pe td t i.on use.
- 10 -
DEEP SUMP
oi l ser ge i s e xperi enced ca u s ~ng loss of oi l
sump s e t ki t shou l d be ins t a ll ed , C- AJ~ 3324A.
Wn er ~
t he
de~F
Thi s i s comp l e t e with a l l necess ary
~oi n t s
a~d
pre ss ~r e momer. ~a r i l y ,
an e xtended oi l pick up
pipe .
OI L PC;·1P
I n a ll case s .che r e t he powe r unit is s t r i pped the oi l pu mp s ho ul d be
c l os e ly examined and i f r e pl ~ c Emen t is ne c e s s a ry use on l y 12G 79 3.
The Coope r ' 5 ' otl p~~p caP~ot be f ~tted t o the se models unl e s s
s ha f t ~ s shor t e nec , which ~oc l d weaken the shaf t a nd c aus e prema t ur e
f ai l ur e .
t~~
COOLn;G SYSTEM
s ust aine d maxi mun s pe e ds a r e ~eq ui red . ~h e e ngi n e tne~s te = =a n
be repl =c e d ' wi t h ~~ ou t l et b laL~ ing sleeve k i t C- AJ J 401 2 t o en s ure the ~2xi­
mum f l o ~ o f coo l a nt to the e r.g~ ne a t a l l t imes .
Do not run ~ it hou t ei ther
thermost ~ t or sle e ve .
W~ Er e
ROAD WHEEL BALANCE
or i gi na l degre e o f ~h e e l b a l a nc e ma y b e affec t ed by tyre wear , cove r
and t u b e r e pa i r s or t yr e r emova l and damage t o the r oad wheel .
Balanc E na y
requir ~ re-c heck i n~ sta t i c al ly and dyn3mica l ly eve=y few thou ~ and miles depender. ~ ~nt ire l y u ;on t he cond i t ions unce~ wh ich t he c a r ha s been ope ra ~ i r.g .
usc t he tyres i r: the best condi t ion o r chos e wit...'L an e ven t r e e d wea r on the
f ront
=a r .
Balanc ing a t yre h avi ng f l a t s o r uneven we a r is not uS ~ 2 1 1y
very s ~~ = e s sful .
T h~
0=
, h en f i t t i ng ~~y non-s ta r. ~a rd whee:s ~ r tyres , it is essential to c heck
t ha t ~~ e t yre car~Q ~ touch t~e b r ake hose unde r ar.y condi tior:s .
I t is ~0 rth
mak i n~ occas iona l check s t h ~ ~ no thing he 5 cha nged ~h i c h ma y pe ~m it t he h ~ s e t o
become ::hafcd .
~NHEELS
m~y
For compe t i t i on u s e , s t r e~ g t h en e d ~h e e l s AR~ 645 5 s hou l d b e f itteci , whi ch
be i den t i f ied by lack of v en t i l ati ng hol e s .
SHOCK :1.BSORB ERS
impr ove d ~and ling s ~ i f f e r shock absorber s C- AHA 64 51 R.H. a nd C -~HA
64 52 L .~ . a re av~ilable f o r the f r ont of al l model s .
Adjustcbl e types 3re
av a i lao :e f or the ~ea r C-AP~ 7906 R. B. 3~C C- AHA 790 7 L. H. 2~t e r chass ~ 5
Fc ~
AN'J- 4 3 3 ;·.
'r he-se requi r e a p la t e 5/ 32" ( 3. 9'.-') be t we en che shock a bs.c r be r- a nd bodv ,
The drop
s ha pe 2 ~~ measureIe ~ ts a re deta i l ed wi t ~ ~he s hoc k ~bso rbe r s .
link: ( 6") s hou l d be rep lace d by t he s eender d 4~- " t ype of the e xisting C2r .
ROAD
S P ~I NG S
-
R~ 2 ~
Jo. h e a vy dut y re a r
( 2 off: i s s t i l l avai lab l e ,
f i xi ng bol t s HBZ C624 ( 4 at-f', .
A taper pa ck i ng i s
ro ad s. p r i.nq AHA
~, 4 6 8
whi c h , ~ q u i r es l o ~g e r
al s o a V a~ l a ble t o ar.g l e t he spr i ngs up or down t o
height . Fa r t No . A_~ 64 56 ( 2 of f ) .
- 11 -
51,;i t
t he requ i r ed r i de
ROAD SPRINGS - Fr on t
The f r ont end may be lower ed using l owerin; k i t C- AJJ 3322 or r a i s ed
by fi tting s pr i ngs AHA a C03 .
S p ri~g s wi l l be ~e ak e ned i f t he s hock a bsorbers are no t i n good c ond i t i on , and it may be f ound tha ~ the s tanda rd
s pr i ngs 2A 4 214 are quit e satisfac t or y with ne~ s hock ab s o r~er s • •
A combinat ion o f kYA 8003 and C- AJJ 3322 '~:i ll e ffec tively s t i ffe n
and s l i gh t l y lowe r t he f r ont .
Thi s wi l l c reat e unders tee r o r correct
over s t ee r •
The ant.Le.rc Lf bar ki t C-AJJ 3314 inc l ude s e 9/ 16" bar 311d r eq ui r e s
th e bot tom suspensi on link t o be drill ed , a l t ernativel y r e ady d r il l ed
l inks a r e a ~a i l ~ l e AHA 702?/ 70 30 .
Opt i onal ~hi cker bar s : -AHT 56
( 5/ 8 1' ) and C-AHT 57 01 /1 6" ) can a l so be ob tained t o co r r e ct ove r a t .ee r
or i ntroduc e under s t ee r a s r equi r ed .
I f no r oll bar has pre vious ly
be en fitt ed , Lns t.a Ll at. Lcr- k Lt; C- AJJ 3357 will be r equir ed ·.·.' i th e i t he r
C- Ai-IT 56 or 57.
3RAKES
On a n o l de r c a r , c l os e a ttention s hould be paid to the co ndi t io ~ of
a l l b r ake pipes and hoses t o e ns ure ~hey have not become c~mag ed o r
per is~ed wi ~ h age .
and h c~~ling wi ll now be gr ea tly i ncre a s ed cnd a tten t i on
rr.u s t he pai d c l os e l y t o 5t op ping .
P er fo ~ anc e
The s t and ard 7" d'::-WO"I a r ranqerreot; is wel l ab le t o t ak e c are of nor~al perform 5Dce , bu t wi l : s uff er f r offi fade during hi gh s pe ed s tops .
Compet iti on l i ni ng s c an b e f i t t ed t c he l p r ed~ ce fad e .and VG 95/ 1
~a t e cia l is ava i l ab l e C- 8G 8998 , 2 sets r equir ed per c a r .
Lined s hoe s
a=e a lso aV3i l ab l e C-8G 899 7 , 4 s e t s pe r car .
The se wi ll ~ e qu i re Do re
peda l eff or t ~h i c h c an be compens a t ed f or by f it t ing Br ake Ser vo Ki t
8G 8 732 .
Conver s ion t o lat e r ~ype di s c f r on t br ake s 1s not approved by the
f ac t o ry b e c a~s e of t he ex~reme di ff i cu l t y of ensur i ng t hat the f ront
br ak e hose r un is correc t t o avo i d i ~ f oul ing ~ h e whee ls .
- 12 -
_ _ ~I!itt-I ,l(·..·
•
'So
. ' 0
INLET PORT
•>:
"
.
'...•-"•.,.
I
. """
•
-r
•
•
0_
.~
I
"' ,i
,
'
!HD
I
~
'. ,
:j
OJ
•
<
0
0
,
~
,
-"
.- '
00
"
0
', 35 •
•
'--~ , ~
•
l,. 'Fi ~.
1.
Inlet port tem plate.
,
•
ISb
. ",.
REMOVE BY
~-- GRINDING
Fig. -4
A secno» through tne flywheel
showing the area where lightening
Fig. 2.
Seetton throug h t he inlet po rt.
is puminlble lOgelhe r with th e
machining dImensions
J<
REMOVE BY
GRINDING
Fig. 3. Section thro ugh the exhaust port.
I
13
B