Performance Uprating


For performance and economy.

Skip to Performance Heads, Carburettors, Superchargers, Exhausts, Engines, Engine Tuning, Engine cooling, Suspension & Brakes

Gas flowing stage II performance head
Gas flowing stage II performance head

A stage 2 head gives a noticeable increase in power, especially when combined with a suitable camshaft and freeflow manifold. The stage 2 includes not only modifying the combustion chambers but also opening out, gas flowing and polishing the ports, as the detailed picture below shows - standard head/right stage two left. All replacement heads are now suitable for unleaded petrol, and it is well worth considering further work to the head if you are having an unleaded conversion. Even if you do not go to stage two, there are benefits to be had from matching the head for compression to your engine block and gas flowing.

Please contact us for pricing.



Standard SU 1 1/2
Midget 1275 carburettors overhauled with uprated needles

The standard SU 1 1/2" carburettors work very well on MGB but the HS4 as fitted 1962-74 do suffer, after many miles, from air leaks especially around the throttle spindles. This will give a poor tickover, often with light acceleration flat spots.

We offer an FOC test for air leaks and jet ovality.

(We also offer distributor ignition advance curve and engine compression tests as a more comprehensive diagnosis for poor running, please see 'tuning')


Early SU HS4 carburettors as fitted 1962-72 also suffer from jet wear due to its fixed needle location. This was rectified with use of floating needles finding its own bias within the jet.

Later SU type HIFF4 1975-80 suffer mainly from air leaks from the sprung loaded butterfly air valve and don't particularly run well on the standard weak ACD needle.

Therefore often poor twin carburetor running is due to:

1. Worn carburettor spindles
2. Worn butterfly edges/air valve
3. Worn jets
4. Worn and incorrect needles fitted per application
5. Float level

We offer overhaul and specialist setting up with a host of needles for different applications from completely standard to include running with freeflow manifold, K&Ns, performance cylinder heads, 25D and 45D type distributors twin 1 3/4" SUs, superchargers and the various overbores of 1860, 1950, 1995, 2100 and 2200cc.

Fitting a Weber carburettor and manifold will release the ultimate power from your tuned MGB engine, particularly if it has an uprated camshaft or increased capacity.

The Weber is particularly beneficial higher up the rev range, and transforms the character of the engine with its throaty race bred roar. Once properly set up its fixed jets mean that it stays in tune and requires no routine adjustment or re-tuning.

Weber carburettor

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Superchargers supplied, fitted and overhauled

Air box options - either standard performance filter or the same with modified original airbox to reduce induction noise (pictures also show optional HS6 carburettor).


Supercharger overhaul


Supercharger overhaul




MGB Supercharger
1980s turbocharger option for MGB giving similar power figures to
our Supercharger ST1 set-up but with more torque from our 2ltr spec.


We fit and recommend mild road billet camshafts where possible for road and fast road use which gives great low down and excellent mid range power and torque. These camshafts help to keep combustion temperatures lower than otherwise and when fitted with a stage 1 or stage 2 supercharged modified cylinder head produce excellent spread of power with a very smooth tickover. Emissions are also keep low with HC ppm levels at least half that of a standard 'B'


We recommend you do not increase the boost of your MG without protection from an octane boost or better still water/methanol injection which we have carried out much testing. Protecting your supercharged engine from detonation is the most important factor long term and water and/or methanol injection is the best at offering this protection.


It is vital to have a flatter ignition advance curve whether running points with dwell or electronic ignition. This can be modified with different strength bob weight springs working better on 45D type distributors or by plotting your own advance curve on electronic ignitions that allow.


On over bored B series 2000cc engines running high boost can suffer from block face cracking between cylinders especially no's 3 and 4 so it is better not to go wild in camshaft choice or boost if you want to use your MG for any thing except rally or racing.

Supercharger nose pulleys

New LMG uprated Moss/Eaton supercharger nose pulleys giving a noticeable and worthwhile improvement in performance. These pulleys are available in two sizes and care must be taken to ensure the engine is correctly set up as boost will exploit any weakness within your engine.

We recommend super unleaded petrol, a good quality octane boost as pictured and a modified distributor advance curve. Alternatively we can set your engine up for enhanced performance in our workshops.

Further tuning can incorporate water/methanol injection intercooling and/or modified cylinder head and camshaft.

Uprated pulleys are available.

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Recommended exhaust options for MGB

B001 Full STAINLESS STEEL system 62-74 model years

MGB Exhaust
B002 as above but for 74-80 models

B013 Standard stainless steel system with bomb type or standard centre box with freeflow extractor manifold

MGB Exhaust
B014 as above but for 74-80 models

Parts also available individually:

  • B012 Freeflow manifold
  • BMG19 Standard downpipe
  • BMG21 Standard centre box
  • BMG121 Bomb type centre box
  • BMG22 Connect pipe
  • BMG27 Connect pipe
  • BMG23 Standard rear box >74
  • BMG28 Standard rear box 75>
  • BMG700 HDR freeflow
  • BMG701 HDR connect pipe
  • BMG702 HDR rearbox
  • C006 HDR freeflow mild steel
  • C007A Connect pipes big bore mild steel
  • C007B HDR rear box mild steel
  • FSMG23 Falcon centre & rear box section >74
  • FSMG28 as above 75>
  • FSMG19 Falcon downpipe

Parts in stainless steel unless otherwise stated. We also offer a full range of Falcon two part stainless steel standard & performance systems, Upgraded carburettor needles, butterflies & re-tuning, exhaust fitting kit may also be required.

Please contact us for for further details.

Exhaust manifold upgrades
Exhaust manifold upgrades

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Our high specification engines are a 2 litre spec which are sleeved and overbored, having tuftrided crank, billet camshaft, increased compression, gas flowed cylinder head with uprated multi layer head gasket and fully balanced reciprocating components.

2 Engines

This gives an enhanced B series engine increased engine flexibility, smoothness and importantly a noticeable increase in torque.

If you have a standard or over bored engine already we can modify with some or all of the following:

  1. Modified ST1 cylinder head
  2. Uprated multi layered head gasket
  3. Billet camshaft
  4. Performance freeflow manilfold
  5. Modified distributor advance curve
  6. ST1 tune and set up

2 litre engine options:

1. This ST1 spec is our most popular engine and runs with the standard 1 1/2" SU carburettors with optional freeflow stainless steal exhaust manifold giving a free revving engine, together with modified ignition advance curve.

Approx 100-105bhp with torque of 129lbf ft or approx 112bhp when using our 270 spec camshaft


With 18% increase in torque this engine allows better acceleration low down in the rev range for easier overtaking.

The engine is far smoother and quieter at tickover with noticeable lower emissions especially the hydrocarbons HC PPM levels, the unburnt fuel part.

Top speed range 107-112 mph.

2. ST2 is similar to ST1 but needs the larger 1 3/4" SUs or single Weber 45 DCOE to breathe with increased camshaft duration and lift etc.

It's a traditional tuned, normally aspirated, spirited fast road engine with a less than smooth tickover due to valve overlap and combustion chamber scaverging, together with hotter running is not everyone's choice but it's great fun for track days.


The Weber 45 option will give more mid range punch but is a very noisy Carburettor for the road with an external breather through a K&N filter which emits oil mist which is not ideal on a hot summers day, unless fed into a catch tank.

This engine spec also requires improved cooling too. See 'cooling'

This spec gives approximately 130-135 bhp and torque 140-145 lbf ft.

Valve bounce is at 6230 RPM and with a new red line.


Acceleration time 0-100mph averages a respectable 33 seconds this being a full 13 seconds quicker than the standard chrome bumper model.

Top speed 117mph @5350

Three choices of performance camshaft are offered with higher valve lift and duration which changes the engine characteristics further, sound and power delivery.

3. ST1 supercharged 6-10psi producing 130-145bhp and high torque at low RPM 155-175 lbf ft.

Acceleration time 0-100 mph in 24-27 seconds depending on boost level. Which is approximately half the time that it takes a standard chrome bumper model to reach that speed.


Top speed is 124mph @ 4750rpm

The engine requires longer axle ratio for over 6psi ideally, due to its high torque. Our choosen crown wheel and pinion option ratio gives 26.1mph per 1000rpm for tubed type axle instead of the standard 21.8 mph, allowing for refined cruising.

NB. Currently this alternative crown wheel and pinion ratio is special order only and not readily available.


All acceleration times in any gear with this top of the range specification engine are again approximately covered in half the time of a standard chrome bumper model 95bhp engine.

The acceleration is smoothly produced up to a maximum of 5000rpm with valve bounce @ 5250rpm being the engine's new red line.

This option is certainly expensive. A big budget is needed but if you have a top of the range MGB, and want to make it go as well as it looks, we can do that for you. Cruising effortlessly, in style with performance on tap in any gear.

Off boost the single 1 3/4" SU will return impressive fuel consumption of around 45mpg touring. Town work returns noticeable better MPG too and overall fuel consumption is similar to standard models.

Emissions at tickover are the lowest of any of our engine specs.

4. ST2 supercharged NLA

We recommended use of a upper cylinder lubricant even though our cylinder heads have hardened exhaust valve seats.


Water injection is recommended which has many benefits especially with higher boost levels, allowing for increased ignition advance and offers engine protection from detonation under load on maximum boost, reducing emissions further too.

Please use E5 super unleaded petrol with our engines and only our spark plugs as supplied which are a special recessed electrode cooler running plug type.

All BHP and torque figures are produced at the flywheel. Approximately 25% of power produced is lost through the drivetrain.


The LMG Full Tune (MGB for example, all years including performance tuned engines)

Items that need to be checked/rectified

  1. Ignition
    Condition of points & dwell, condenser, low tension, bob weight spring tension, mechanical & vacuum advance, rotor arm, distributor cap, plugs, lead resistance etc. Ignition then set to suit engine, compression & vacuum strength etc.

  2. Rockers & valves
    Tappet clearance, rocker shaft & rocker bushes, rocker box gasket & seals, compression test

  3. Carburetors/fuel injection
    CO & HC levels, condition of jets & needles - correct application for for air filters & state of tune etc. Linkeage for both choke & accelerator. Check condition of cables, breather hoses, air leaks, butterflies/over run valves, spindles, air filters & seals. Carburettor balance & mixture. Throttle return springs. Fuel pipe & filter. Float levels. Injector spray (TR5,6 etc)

  4. Road test & fine adjustments

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PARTS as necessary - for example MGB

1 GCS2101 Points
1 GSC2109 condenser
1 GRA2101 Rotor arm
1 GDC136 Cap
1 GHT7003K HT lead set
1 GUG70033VC Rockerbox gasket
4 GSP4362 plugs
2 12A1358 Rocker seals
1 CAM5226K Breather hose set
2 GFE1003 Air filters standard
2 KNE240 K&N air filters
1 27H7758 Breather Diaphragm
1 AHH6465 Airbox seal
1 AEC2075 Return spring
1 TT1903 Bob weight springs
1 37H4229M Vacuum pipe
2 12B2095 Vacuum connectors
1 GFE7015 Fuel Filter
1 GFE6003 Rocker box cap
1 37H2981 Low tension

Additional parts & labour may be required e.g. for carburetor & distributor removal & stripdown. VAT to be added. MGOC/MGCC discount not included.

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Engine cooling

Cooling benefits can be found by fitting an expansion bottle to all years of MGA and MGB 1962-74.

In addition an aluminium radiator for tuned B series engines.


Expansion tank

Cooling fan upgrade

Aluminium radiator upgrade

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For road-holding and ride comfort.

Tracking, tyre replacement and correct balancing of wire wheels. In-house kinpin reaming. Hub extraction with oil seal replacement.




Suspension - kingpin reaming

Suspension - kingpin reaming

Suspension - hub extraction



MGB rear suspension upgrade components

MGB /MGBGT - Stage 1

1. Lowering

It is quite straight forward to lower a rubber bumper MGB to chrome bumper height. The cars sits approximately 1 inch lower, which not only improves its sportscar appearance but also significantly improves handling by lowering the centre of gravity and reducing body roll, without compromising the ride comfort.

Basic lowering includes fitting new front coil springs with either:

a) lowering blocks at the rear (see picture) b) replacement lowered leafsprings

Rubber bumper MGB cornering after chrome conversion
Rubber bumper MGB cornering

2. Telescopic rear dampers/shocks

Replacing the rear leverarm dampers with telescopic units gives an improved ride and better road holding particularly over bumps by allowing the rear wheels to follow the road surface rather than hopping across it. They also eliminate any quality problems (see our Spring 2000 newsletter) with reconditioned leverarm shocks

Fit spax rear shocks & mountings (see picture)

Chrome bumper MGB cornering
Chrome bumper MGB cornering

MGB /MGBGT - Stage 2

Please contact us for details of the many further improvements to your MG's suspension which we offer.

For additional information please contact Russell at LMG

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Often older brake systems, especially drum brakes, can be improved just by proper servicing. Various improvements are possible such as fitting braided front hoses for better feel, pad upgrades (e.g. MGB V8 pads fit standard MGB front callipers), vented discs, and servos where not previously fitted.