ADVICE AND TECHNICAL DETAIL FROM CHRIS
WITOR

THE 2000 Mk2 ENGINE - ATTENTION TO DETAIL FOR
TRACTABLE ROAD USE

The 2000 Mk2 engine is difficult to modify for increased
bhp without losing tractability. Little was designed to compliment
the 2000 Mk2 engine's characteristics. Rationalization resulted in
the 2000 engine using components originally designed for the 2.5 -
in particular the inlet, port, valve and manifold size which lost
the induction velocity that endowed the 2000 MkI with superior
torque and response. Indeed, the MkI produced 90 bhp (net) @ 5000
rpm with 117 lb ft torque @ 2900 rpm, whilst the Mk2 produced 84 bhp
(Din) @ 5000rpm with100 lb ft torque @ 2900 rpm. The 2000TC 1975
onward produced 91bhp @ 4750 rpm with 110 lb ft torque @ 3300 rpm,
the increase here can be attributed to its 1 ¾" carburettors with
improved flow distribution of it's inlet manifold, and 1 7/8" OD
exhaust front & centre pipes. The MK2 head with its larger studs
did solve the Achilles heel of the 2000 MKI - its tendency to blow
head gaskets.

To maintain tractability, especially in the saloon body
shell, I wouldn't recommend using camshafts with more than 270ْ
duration, and not more than 260ْ duration if used as a tow car.
Indeed the engine won't need to rev beyond 6000 rpm with the
modifications listed in this article.

The 2000 Mk2 engine does have advantages over the 2.5:
the engine is smoother, free revving, and the crankshaft weighs
14lbs less. If you are planning to modify a 2000 MK2 engine, I would
recommend the following:

Deck the block - the block should be skimmed so that the
pistons run 0.10" above the block face; the Head gasket is .040"
thick, thus results in .030"deck clearance. This reduced squish area
and improved piston 'quench' improves the quality of combustion and
reduces the tendency to pink. This is a high priority
modification.

Use flat top pistons - the domed piston was merely
factory rationalisation allowing a 3.400" high 2.5 PI head and
pushrods to be used directly on the 2000. If the block is recessed,
use flat top 'AG 900' head gasket after skimming the block, which
would typically have over 0.035" removed when decking. Ensure piston
skirt clearance is towards the upper limit to avoid seizure. Some
after market pistons appear to expand more than original Stanpart
Brico versions. I would recommend 0.0025" for fast road use, however
one is at the mercy of the variable expansion characteristics of
aftermarket pistons Pistons should be balanced by weighing after
decking. Use 151073 8" long pushrods if the head is skimmed to suit
flat top pistons. Over Boring to increase engine capacity is another
option, however if boring out beyond +.060" fire ring size of the
AG900 gasket is exceeded, then a costly special oversize head gasket
will be required. Over boring will increase capacity as follows:
+.020" 2025cc, +.030" 2038cc, +.040" 2052cc, +.060" (76.2mm) 2079cc,
77mm 2123cc, 78mm 2179cc. Beyond this point the risk of water jacket
penetration increases, but for the adventurous: 79mm 2235cc, 80mm
2292cc. 80mm also beneficially reduces the weight of the block by
approximately 10 Lbs. I offer over bore pistons of 77mm, 77.5mm
& 78mm, but the little ends need special bushes making to suit a
20mm gudgeon pin.. Less needs removing from the top of the block
when decking with these pistons, due to their taller compression
height. Use a 219016 cylinder head with its superior flow
characteristics. Testing I commissioned following port examination
of many 6 cylinder heads revealed that @ .500" inlet valve lift,
these head flow up to 10cfm (cubic feet per minute) more than all
earlier heads. Early heads flow around 60cfm and 219016 around 70cfm
@ .500" inlet valve lift.

'Gas flowed' heads are poor value for money - ensure any
such heads are backed by a flow lift chart. The 219016 2.5 head,
which was typically 3.475" tall, will need skimming to suit the 2000
engine. Amount depends on: rebore size, valves used, whether the
engine is decked, and camshaft used. I can supply a range of flow
profiled 214N valves and copper bronze guides also suitable for
un-leaded petrol, specification of which is second to none - details
on request. I can also calculate combustion chamber volume required
and approximate skim height prior to any buretting of chambers - for
our customers, or see Triumph 2000/2500/2.5 Register service notes
page 1.129.

Crankshaft - Any grinding should be carried out prior to
decking. Ensure the crankshaft is phase corrected and stroke ground,
as this will make piston heights more consistent when decking.
Gosnay's engineering at Romford in Essex can phase correct and
stroke grind - I'm sure there are other competent engine
reconditioners that offer this service too. Rough edges on the
crankshaft can be smoothed out and blended in and leading edges of
counter balance weights may be knife edged, the aim being to make
the crankshaft more aerodynamic to reduce windage. Up to 1lb in
crank weight can also be lost with such work. Knife edging is low in
order of priorities, and should only be carried out by a craftsman
skilful with a grinderette.

Flywheel - It is highly beneficial to acceleration in
the lower gears to have the flywheel lightened. 7lbs can safely be
removed by turning in a lathe and a further 3lbs by slotting in a
milling machine, which takes the weight (less ring gear) down from
25lbs to 14lbs. An aluminium flywheel weighing 12lb 4oz is available
on request, but currently costs nearly £400.00.

Balancing - Crankshaft, flywheel, clutch cover and
pulley may all be balanced.

Bearing Shells - Always use superior original Vandervell
VP2; lead indium lead copper crankshaft bearings when available.
Mains are currently available in standard, .010" .020" .030". I have
a limited quantity of .010" big ends, after market lead copper big
ends are available for standard, .010" .020" - avoid inferior
aluminium tin aftermarket bearings.

Connecting Rods - these are not highly stressed on a
2000 engine, with its short stroke. If of known history - and the
engine hasn't run with a failed big end bearing, or ingested water
which could bend a rod, then it should be safe to re-use. However
check: the little end bearing for wear, or possible spinning in the
rod eye. Lay the rods on a flat surface to ensure they aren't bent -
tell tale wear marks on used pistons skirt and crown can be an
indication - I have seen a bent rod where the big and little end
weren't parallel in one instance. Connecting rods may be balanced by
weighing, preferably on two accurate scales, with the little end on
one set and the big end on the other, so that it can be seen where
to remove any material. However factory matched sets are typically
fairly good.

Inlet Manifold - The common 1½" Stromberg or SUHS4 inlet
manifold has a major imbalance of flow across the cylinders, apart
from lacking induction length thus velocity that could have endowed
the engine with torque.

CYLINDERS

1

2

3

4

5

6

CFM STD

72

43

74

75

42.5

75

CFM reworked

79

76

81

80

75

78

As one can see cylinders 2 and 5 are severely starved.
This will also cause a weaker mixture on 2 and 5. Heavier fuel
droplets will not pass freely around the flat plate obstruction into
which they flow, as will the airflow, which is less impeded. I can
offer re-working of such manifolds for currently £129.25. This
modification makes a significant improvement to the upper mid range,
from around 4000rpm, but makes no difference to bottom end
power.

Carburettors - for response and torque I would recommend
the 1½ Stromberg, preferably the rare CDS fitted from mid 1969 to
1970 that can be adjusted from below. These can be used with a 6J
needle, which has proven versatile on 2000 engines. For top end
power, used 1¾" SUHS6's together with their manifold and water pipe
work. The HS6 long runner inlet manifold has superior flow
distribution to the short runner Stromberg version, however both
exceed the maximum flow capability the 75 CFM of a typical 219016
head - which isn't good for bottom end torque. In factory spec, the
2000TC with its production 219015 head permits 65 CFM @ .350" valve
lift. Its SUHS6 inlet manifold flows 88 CFM on cylinder 1, 23 CFM
more than the production engine permitted. The HS6 manifold has an
average flow of 81.66 CFM, still 16.66 CFM more than the head and
cam combination allowed. One can see that incompatibility of this
manifold wasn't conducive to producing induction velocity, thus
bottom end torque. If only the factory had developed a manifold
specifically for the 2000 MK2, with long runners flowing around 60
CFM, the torque could have been transformed.

CYLINDERS

1

2

3

4

5

6

CFM STD

88

77

78

83

81

83

To achieve strut turret to air box clearance with SUHS6
induction, the engine cross members with holes off set to suit, must
be used, or re-drill existing cross member just to the left (NS) of
existing holes. Then use 2 7/16" thick packaging pieces on the right
hand (OS) with suitable longer bolts.

Some owners have successfully fitted 1½" SUHS4's to the
HS6 manifold to improve torque and throttle response for towing.

Triple twin choke Webbers and even triple SU are an
aftermarket option for top end power, use of which is outside my
experience. MPG is likely to drop with both. Lucas PI fuel injection
is also an option, offering good torque - although optimising
metering unit calibration to engine spec may prove a challenge.
Having said that, I remember an instance where a 2000 short engine
had been wrongly supplied and fitted to a 125bhp 2.5PI, including a
311399 camshaft, with no adverse effects to fuelling when driven. It
was noticeable that this engine was smoother and free revving, but
didn't quite have the torque one would expect from a 2.5.

Exhaust System - Replacing the standard 1½" 00 tail pipe
with at least 1 7/8" OD is the first modification to make and makes
a significant improvement to top end power whilst extending rev
range. The 1975 2000TC had a 1 7/8" OD front pipe and centre section
as standard, but will benefit from replacing the restrictive 1 ½"
tailpipe. A 6-3-1 extractor manifold will increase BHP by around
10%. The manifold and system should be worth at least 20bhp. Where
270˚ or more cam duration is used, the 'super sport' 2" OD entry
rear silencer box makes a further improvement to top end power.

Ignition, I would recommend tried and tested
Piranha/Newtronic optical ignition with a sports ignition coil, use
cooler NGK BP7ES or even cooler BP8ES depending on plug colour after
use. Devices such as Lumenition to electronically map advance curve
should be beneficial, but I have no personal experience of their
use.

Lubrication, ensure oil pump rotor clearances are
acceptable. I supply a blueprinted pump where the rotor end float is
typically reduced from 0.006" to 0.001" - 0.002" to reduce internal
leakage and improve displacement. Use running in oil for 500 -1000
to prevent bore glazing where new piston rings are used. Then use
quality motor oil. I use Valvoline Synpower SAE 5 W-50. Always use a
magnetic sump plug, this is especially beneficial on an engine that
has been re-bored and will deposit hone plateau and ring swarf.

After much thought and puzzlement I now got to wondering
how the clutch managed to clear at all.

Camshaft, I would recommend the following for 2000
saloon road use.

Factory 307621 10˚ 50˚ 50˚10˚, 240˚ duration, .215" lift
-heavy towing/ bottom end power, but with higher lift ratio
rockers to extend rev range. Compression ratio 8.5-8.75:1.

Factory 306785 18˚ 58˚ 18˚, 256˚ duration, .220" lift -light
towing/semi fast road. Compression ratio 8.75-9.1:1

Factory 308778 25˚ 65˚ 65˚ 25˚, 270˚ duration, .232" lift
road/fast road. Compression ratio 9.25-9.45:1

CW 25˚ 65˚ 65˚ 25˚, 270˚ duration, .261" inlet .232" exhaust
lift, fast road with 1¾" or triple carburettors for the
adventurous there are longer duration profiles available but at
the expense of torque. which outweigh BHP advantage. Roller
rockers with higher lift ratio are a beneficial modification,
primarily with higher volume inductions which can take advantage
of extra valve lift. Bear in mind that an 1.5" Stromberg
carburettor flows around 84 CFM (feeding 3 cylinders) which can be
beneficially increased to 91 CFM by using a spherical induction
stub on the intake face, so more than .365" lift would be of
limited benefit with high velocity low volume induction.

VALVE LIFT RATIO CHART

Chris Witor -
Jan-04

Original Camshaft Application

OE Cam Part no.

Timing Degrees

Duration Degrees

Cam Lift

Valve Lift @1.42 Std

Valve Lift @1.5

Valve Lift @1.6

Valve Lift @1.7

2000 TC 1975 'ML'
MM 20001 on MK3 GT6 and
TR250

307621

10/50

240

.215"

.305"

.322"

.344"

.365"

MK2 2000 'ME'

306785

18/58

256

.220"

.312"

.330"

.352"

.374"

PI MkI and Mk2
to MG 50000
MK2 Vitesse
& GT6

308778

25/65

270

.232"

.329"

.348"

.371"

.394"

After Market Performance
Profiles

BCF1, CW Profile

---

25/65

270

.261"

.370"

.391"

.417"

.443"

NB: At around and beyond .390" valve lift with standard
rockers the rocker may run off the inside edge of the valve at full
lift. To prevent this either use our performance valves with
extended tip or have the rocker pedestal shortened by half the
increase in valve lift to maintain correct rocker geometry. Careful
checks should be made with the tip of a roller rocker at full lift
too.

A set of 12 roller rockers currently cost £250+ vat, so
the cost compares well with the cost of a re-profiled camshaft,
which would require new followers, gaskets and a considerable amount
of labour to fit. Furthermore if the job is being carried out on a
budget, the 6 inlet rockers only may be fitted for virtually the
same power gain, but at a cost of only £125 + vat. Alloy roller
rockers weigh 45g less than OE, so if all 12 are changed, a saving
of 300g reciprocating weight will result.

Valve springs - I successfully use early PI double
springs (102564 inner 149633 outer) with .430" valve lift for fast
road use, but this is with reduced reciprocating weight: 12 alloy
valve spring caps -saving total 8g, 214N flow profiled valves saving
5g per valve x 12 = 60 g, and Mk1 8 9/32" long (which only fit a
3.400" tall mk2 head) slim stem lightweight pushrods. Reducing
reciprocating weight reduces inertia loadings - reducing the need
for higher spring pressures to some degree. Ensure that these
springs are used with 0.150" thick inner spacer collars 149717,
under the inner spring. Seat pressures are typically; Inlet 30 lbs
at 36mm, Exhaust 38 lbs at 35mm. Beware of green striped go faster
springs which are far too hard for road use; inlet 69 lbs at 36mm,
exhaust 80 lbs at 35mm! By comparison Standard MKI 2000 ; Inlet at
36mm 12 lbs, exhaust at 35mm16 lbs. Too high valve spring pressure
causes unnecessary loading & wear to: cam followers, lobes,
bearings, timing chain, sprockets, pushrods, rockers, rocker shaft,
valve tip , valve seats -as well as power loss. Yellow striped 'fast
road' TT springs are; inlet at 60 lbs at 36mm, exhaust 72 lbs at
35mm - still hard, but possibly a safer option to avoid valve bounce
if going beyond .430" valve lift and/or 270 Degrees duration thus
6000rpm.

Chain, Sprockets and Tensioner, may be converted from
single to 2.5 spec duplex, for greater durability.

Final Drive/Gearing choice is more critical with a 2000,
than a 2.5. A 2000 will struggle if too highly geared, a 3.45:1 2.5
diff isn't a suitable option. One has to choose between; a 3.7:1,
originally fitted to all 2000 Automatics, and 1975 on 2000TC, a
4.1:1 from 2000 manuals to 1975, or possibly even a 3.89:1 - a
Leyland ST ratio, originally for the Dolomite, for which
remanufactured CWP's are now available.

If too highly geared, a car will typically struggle to
accelerate through its useful rev range in overdrive top. However a
car will feel more refined with better MPG when over geared. If too
low geared, a car will have more of a fun feel, accelerating briskly
through the gears, but will feel stressed and un refined on the
motorway, with MPG suffering. As a guide, a 2000 with 270 or more
degrees cam duration and 1 ¾" SUHS6 Carburettors will only pull a
4.1:1 diff ratio. If 1 ½" carburettors are used with 270 degrees
duration, then a 3.7:1 may just be suitable. Rolling radius of tyres
and overdrive ratios are another factor. Overdrive ratios are as
follows 'A' type 22%, 'J' type 1973 - May 74 25%, 'J' type 2000TC
1975-77 28%. Interestingly the 2000TC was very high geared, with a
3.7:1 Diff, 28% overdrive, and ran with 1 ¾" SUHS6 carburettors.
This only worked because of its short cam timing, 10º 50º50º10º,
240º duration with .215 Lift.

For those that find this article a bit overwhelming,
this modifications guide in stages of priority may help.

Ensure restrictive 1 ½" tailpipe rear silencer box is removed.

Fit higher lift ratio rockers, ensuring valve springs are
suitable.

Fit a 6-3-1 extractor exhaust manifold.

Prepare a 219016 head, with unleaded inserts, 214N flow
profiled valves, copper bronze guides, suitable valve springs with
alloy caps. - Ensure skimming takes into account cam duration,
bore size and any decking of the block.

Sort out piston heights/ deck clearance.

Select Camshaft.

Fit a lightened flywheel -sooner if the gearbox is removed.

Flow balance any 1.5 Stromberg/ SUHS4 inlet manifold.

Consider overbore - but decide before 5/ Decking.

Rolling road test to set fuelling - especially with SU's, and
optimise ignition advance.

Of course one can always 'simply' fit a 2.5 engine, but
this option seems somewhat defeatist. A moderately modified 2000
will easily out accelerate any standard 2.5 carburettor models,
whilst more highly modified versions can out accelerate a standard
2.5PI.

INLET MANIFOLD WATER HEATER BANJO
REMOVAL

Anyone who has attempted to undo, or tighten this Banjo
Bolt will usually regret doing so, as it almost invariably breaks
off across the drillings, due to weakening by rust, and seizure of
the threads in the manifold. I have only ever removed one without
breakage, in many attempts. When broken off, this usually reveals a
Banjo so clogged with rust flakes, that any coolant circulation
would be very restricted. Worse of all, the broken ½" BSP threads
remain in the aluminium manifold. The manifold has to be removed to
proceed with repair. I have attempted to remove the broken threads
by arc welding in a bolt into the remaining stub, and after much
heating and use of penetrating oil attempting again to undo. If it
does start to turn, it normally tears most of the soft aluminium
thread out of the manifold. I had accumulated a quantity of
manifolds, mostly 2000 MkI, which I passed on to my machinist who
has made a special fixture to hold these in a vertical milling
machine. The broken threads can then be accurately bored out to core
size, the remaining spiral of thread then be twisted out as a coil
and the thread cleared with a tap.

I can supply such manifolds on an exchange basis. Thread
removal costs £19.98 per thread plus an exchange deposit of £17.63
per manifold including VAT. On some manifolds where the front
adaptor 138810 looks wasted away by rust, I have had these machined
out too, which also costs £19.98 and supply a replacement in brass
for £4.70. New Banjo Bolts, with washers costs £9.40 each, and I
have a few good used Banjos for £5.88 each, whilst stocks last. I've
also had repaired a small quantity of Mk2 Stromberg manifolds, more
will be repaired if there is sufficient interest.

Purpose of heating

The venturi of a carburettor causes an air pressure
drop, which causes a temperature drop which cools surrounding
surfaces. Fuel/air mixture hitting cool surfaces results in fuel
dropping out of its suspension within the mixture. This causes a
weak mixture, especially with a cold engine on a cold day, hence the
need to pull the choke out increasing the amount of fuel supplied -
and consumed. Heating the inlet manifold helps prevent this adverse
effect. PI's don't have manifold heating because there is no venturi
and subsequent cooling.

History

There are four part numbers for the MkI 2000 Inlet
Manifold, 306649, 307044, 307614 and 144517. I would describe as;
rear exit for vacuum servo hose, central exit for vacuum hose,
central exit for vacuum servo hose with facility for remote closed
circuit breather blanked off, and central exit for vacuum servo
hose, with remote closed circuit breather union, used. There are two
part numbers for the Mk2 inlet manifold 309032, which used closed
circuit breather unit, 2000 up to ME 50 000, after which this remote
breather was removed, and core plug 154053 used to blank off the
hole. RKC0127 was then used on 2000 Mk2 from ME66396, and all 1974
2500 models, with 1 ½" SUHS4 Carburettors. The 1975 onward models:
2000TC, 2500TC & 2500S used RTC1811 (TKC2256 Australia) to suit
1 ¾" SUHS6 Carburettors. This manifold doesn't use a Banjo union,
but cast in steel pipe. Rusting of this water pipe where the Hoses
fit is just becoming a problem in some instances.

NEW PRODUCT - ROLLER ROCKERS

A new generation of high lift roller rockers is now
available from Chris Witor.

The object of increasing valve lift is to increase power
with minimal if any loss to bottom end torque.

These are a well engineered product featuring:

A hardened steel roller tip to eliminate drag back load thus
wear to the valve and guide.

A bronze bush that runs on the shaft at a closer clearance
than original thus reducing noise, with better frictional
qualities than iron on steel.

Aircraft alloy body - original rockers weigh around 70 grams
each, alloy versions just 45g each thus a total saving of 300g
reciprocating weight.

These are a direct replacement for original rockers and
are available in three ratios: 1.5:1, 1.6:1 & 1.7:1. Beyond
.390" valve lift, rocker geometry checks should be made to ensure
that the roller tip isn't running too close to the inside edge of
the valve. If so this can be reduced by shortening the rocker
pedestals by half the increase in valve lift, or by using Chris'
214N performance valves with extended tip. However, this isn't a
problem with any of the production cams fitted to the 2000/2.5 range
as the chart below shows:

VALVE LIFT RATIO CHART

Chris Witor -
Jan-04

Original Camshaft Application

OE Cam Part no.

Timing Degrees

Duration Degrees

Cam Lift

Valve Lift @1.42 Std

Valve Lift @1.5

Valve Lift @1.6

Valve Lift @1.7

2000 TC 1975 'ML'
MM 20001 on MK3 GT6 and
TR250

307621

10/50

240

.215"

.305"

.322"

.344"

.365"

Vitesse and GT6
2000 MK1

306632

18/58

256

.220"

.312"

.330"

.352"

.374"

MK2 2000 'ME'

306785

18/58

256

.220"

.312"

.330"

.352"

.374"

PI MkI and Mk2
to MG 50000
MK2 Vitesse
& GT6

308778

25/65

270

.232"

.329"

.348"

.371"

.394"

PI MK2 from 1973 MG 75000
TR6 'CR'
2500
TC 1974 to MM 20000

311399

18/58

256

.240"

.340"

.360"

.384"

.408"

TR5 and Early TR6 'CP'

307689

35/65

280

.252"

.357"

.378"

.403"

.428"

After Market Performance
Profiles

BCF1

---

25/65

270

.261"

.370"

.391"

.417"

.443"

TH5

---

---

280

.282"

.400"

.423"

.451"

.479"

Hypothetical }

---

---

---

.290"

.411"

.435"

.464"

.493"

Examples }

---

---

---

.300"

.426"

.450"

.460"

.510"

Ensure valve springs are suitable for extra lift. Early
PI, TR5, Mk2 Vitesse type; inner 102564 and outer 149633 running
with .150" thick lower collar 149717 have proven capable of handling
up to .430" valve lift at 6000rpm. At this sort of lift - in
particular, alloy valve spring caps and lightweight 214N performance
valves should be used to reduce reciprocating weight. Available
ratios can be mixed if desired, typically using more lift on the
inlet, than exhaust valves.

Extra lift is particularly beneficial to power output
with a high volume induction, therefore in order of benefit: 2.5 PI,
SUHS6 carburettors and manifold, Mk2 1½" Stromberg or HS4, and of
least benefit to a 2000 MkI with its high velocity/low volume
induction.

Cost is £146.88 for a set of 6, or £293.75 for a set of
12, including VAT.

This article first
appeared in the February 2004 SIXappeal
magazine.

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