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DIAPHRAGM SPRING - Verto types including injection

The Verto/Valeo type diaphragm included the pressure plate in its assembly, much like a 'normal' car set-up. The spring being of the 'finger' type as opposed to the disc spring used on earlier, three-piece assemblies. There were originally three diaphragm specifications using progressively stronger springs - small-bore, big-bore, and Metro Turbo. Later joined by the type used on the injection cars, though most definitely not interchangeable. Initially, the biggest problem was the Turbo ones were never really available on their own. If you wanted one you had to buy a whole clutch/flywheel assembly - the cost exorbitant. Rover originally believed that if the clutch plate was worn out, then the flywheel and pressure plate would be too. It has only been recent times that the diaphragm/pressure plate has been available on it’s own - but not until after the Turbo unit became unavailable. Even that has changed recently with the cessation of the Turbo diaphragm as a service part.

During a discourse with the editorial staff at Mini Mag, it was decided the build feature presented an ideal opportunity to demonstrate just exactly what such an engine build is capable of in days where it's generally believed you have to have an all-singing, all-dancing 1380cc engine to have an enjoyable road burner - leaving those with very limited budgets a little depressed. During a discourse with the editorial staff at Mini Mag, it was decided the build feature presented an ideal opportunity to demonstrate just exactly what such an engine build is capable of in days where it's generally believed you have to have an all-singing, all-dancing 1380cc engine to have an enjoyable road burner - leaving those with very limited budgets a little depressed. So the idea was to finish the engine off using a relatively 'mild' specification to maximise drivability. The camshaft used was the fantastically versatile Swiftune Racing SW5 profile that provides drive from nowhere up to 7,000rpm - d

MSE6 - POST 1992 Unleaded Stag

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. Three-angle valve seats in head. Super-quality MG Metro valves modified to increase airflow. MSE6 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head Part No Applications: MSE6, TAM1059, TAM1061, TAM2069, 12G1963, 12G1015, ADU4905 Inlet Valves: 35.6mm(1.401") dia. Original equipment type P/No. TAM1059 Exhaust Valves: 29.2mm(1.150") dia. Original equipment type P/No. TAM1061 Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069 Valve Guides: AE Hepolite cast iron P/No. 12G1963 Valve Springs: Nominal 140lb. Max actual valve lift 0.400" P/No. 12G1015 Stem Seals : Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905 Chamber Volume: Nominal 20cc Combustion chamber volume used to give slight static compression ratio increase over

MSE6 - POST 1992 Unleaded Stag

MSE4 - Post 1992

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. MSE4 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head Part No Applications: MSE4, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905 Inlet Valves: 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544 Exhaust Valves: 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106 Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069 Valve Guides: Magnesium bronze P/No. C-AEA526 Valve Springs: Nominal 180lb. Max actually valve lift 0.500" P/No. C-AJJ4037 Stem Seals: Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905 Chamber Volume: Nominal 20cc Three-angle valve seats in head. Cooper S size valves with current maximum flow profiles and Tuftrided for durability/longevity when used with unleaded fuel (hence 'black' finish).

MSE4 - Post 1992

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. MSE4 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head Part No Applications: MSE4, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905 Inlet Valves: 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544 Exhaust Valves: 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106 Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069 Valve Guides: Magnesium bronze P/No. C-AEA526 Valve Springs: Nominal 180lb. Max actually valve lift 0.500" P/No. C-AJJ4037 Stem Seals: Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905 Chamber Volume: Nominal 20cc Three-angle valve seats in head. Cooper S size valves with current maximum flow profiles and Tuftrided for durability/longevity when used with unleaded fuel (hence 'black' finish).

MSE3 -Pre 1992

Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. MSE3 - PRE 1992 unleaded Stage 2 (Road Rocket) large-bore head Part No Applications: MSE3, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905 Inlet Valves 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544 Exhaust Valves 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106 Exhaust seats Latest type Beryllium-based for lead-free fuel P/No. TAM2069 Valve Guides Magnesium bronze P/No. C-AJJ4037 Valve Springs Nominal 180lb. Max actually valve lift 0.500" P/No. C-AEA526 Stem Seals Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905 Chamber Volume Nominal 20cc

Engine - Running in Procedure

This is another of those subjects that crops up on the message board frequently. I am constantly surprised by the number of engine builders - or people who charge other folk for building engines at any rate - that never hand out such an information sheet. It seems pretty daft to me that having taken a wad of money off of a customer for an engine you've lovingly put together, you'd want to help that person get the very best out of the engine. And the running/breaking in procedure is absolutely crucial. It at least ensures no damage is incurred when the engine first bursts into life. A collection of the usual suspects have explained their own methods on the board, along with various others - many of which probably work just as well for them, a few which are down-right dubious. Following is a sheet I administer with every customer engine I build.

How does this affect performance? Not as many folk believe, that’s for sure. For a start, lightweight flywheel/clutch assemblies don’t necessarily give rough running at idle, particularly where a performance cam is used. Nor do they make the engine produce MORE power. BUT they do make a difference to the ACCELERATIVE performance of the car - and that is what we’re most interested in most of the time! Basically, the engine sees the car as a weight to move, via the gearbox. The combustion pressures created by your common or garden suck-push-bang-blow engine have to accelerate not only the mass of the car as a whole, but the mass of the engine internals too. However, the engine can only accelerate the car at a certain rate with what power is left over after the engine internals have consumed their share. The lighter the rotating and reciprocating parts are made the less power is consumed by them, leaving more to actually accelerate the car.

Since the reasonably recent publishing of a certain Mini tuning, performance and maintenance guide that has strangely coincided with a batch of new readers/devotees of a certain prolifically quoted 'bible' on A-series engine modifications - the subject of all things cylinder head have bounced into the fore once more.

Something I was heavily canvassed over at this years (2003) Mini in The Park event whilst doing duty as Mini 'agony aunt' and 'doctor'… In particular the subject of the combustion chamber was foremost in discussion since the aforementioned 'guide' exhibited a number of wildly different chamber profiles with very little in the way of supportive technical information. Now, I have considered the pros and cons of doing this missive. On one hand, I am not out to increase sales of said guide since I'm not one of its supporters in any way. On the other I am certainly not attempting to belittle the efforts of the featured company as they have long been at the forefront of perf

Cylinder head - Suitability basics

Whatever else owners do to their Minis by way of interior/exterior modifications or none at all, a very large proportion desire and search for an increase in engine performance.

See bottom for useful part numbers.

Now this may not be super-sonic speed-inducing power, it could just as well be for maximum economy. In either case, it's the engines volumetric efficiency (VE) under scrutiny - it's ability to breath in as much correctly proportioned air/fuel mix as possible in any given situation. Although the induction/exhaust system plays an important part, there are effectively two major factors that dictate performance increases - the camshaft and cylinder head. The induction and exhaust elements (stage one kits, exhaust systems, etc.) and camshafts are covered in various other articles in my 'Corner'. So here we'll have a look at cylinder heads and dispel some of the myths and legends surrounding them.

DIY enthusiasts often believe that building an engine to give excellent all-round road performance is beyond them. Mainly from comparisons made between what they have been able to achieve and what specialists say should be achievable from any particular type of engine build.

Generally scrambled further by the non-perfect match of parts and components used between aforementioned specialist and erstwhile DIY-er, and the ritual 'nose-tapping and knowing winks' display of those specialists. Something you can very nearly 'see' even when talking to such folk on the phone - or that inimitable 'ah, yes, well…' So some form of 'black art' is implied. Whilst there is most definitely a degree of 'feel' involved between the real specialist's results and those of just a good engineer - the bones of the deal is subject to no such thing and is certainly within the capability of the DIY enthusiast given the necessary information. And that has been the problem.

Engine - Reliability

I've been having quite another chuckle lately at some stuff I've seen in print (and heavily and heatedly discussed by internet) on the subject of 1380cc engines and their professed unreliability. Although I know I have been at pains to explain to folk you don't have to have a 1380cc with very sporty cam profile and so on to have a decent, satisfyingly quick road car - but this reliability problem is absolute hogwash.

Properly built and maintained, these engines will last every bit as long and reliably as any other A-series unit. Ask the likes of Swiftune Racing or MED - they've been churning out 1380cc engines for the masses for years with precious few problems. It's the 'properly built' and 'properly maintained' that are the problems. But then these are the same problems that affect any engine's longevity. Those and selecting an engine specification that best suits your usage and temperament as far as maintenance goes.

RUNNING IN NEW ENGINES

Install engine. It is absolutely imperative that the cooling system is more than sufficient to deal with any temperatures likely to be produced by the engine. More power means more heat to be dissipated. A standard radiator is very unlikely to be able to cope with a reasonable power increase over standard.

Do not fill cooling system yet. Set clutch throw-out and free-play take up. Double-check all connections electrical, oil, fuel and cooling system. Put in engine oil – use a cheap multi-grade mineral oil. DO NOT use either semi or full synthetic oils. They will stop the rings from bedding in. Remove spark plugs, and spin engine over in bursts of a few seconds to pick up oil pressure and prevent starter motor damage. DO NOT start engine until oil pressure picks up.

Once oil pressure is showing, check ignition timing statically. Set to figure advised by distributor maker, or if no figures available, set at around 6-8 degrees BTDC. Re-fit spark plugs a

To go in to all the possible permutations would take a few chapters on it’s own. Suffice to say that the Metro had a few weirdo fitments such as cable operation, an in-line ‘damper’ (some got fitted to Minis too - eek),

Terminology -
BBU - Big Bore Units
SBU - Small Bore Units

NOTE: This information is largely concerned with transplanting a large-bore engine into a small-bore engined Mini. For further information on clutch and flywheel assemblies in particular, refer to relevant separate article.

Terminology -
BBU - Big Bore Units
SBU - Small Bore Units

Is this familiar? - You take the small one out; you put the big one in. In, out, in, out, shake your fist about, you do the hokey-cokey and you turn around, that’s what it’s all about...

Terminology -
BBU - Big Bore Unit
SBU - Small Bore Unit
Bodge - English term for 'make do' engineering- assured to fail at an in opportune
Moment.
Dizzy - Distributor

NOTE; this information is largely for transplanting large-bore units into small-bore engined cars.

Is this familiar? - You take the small one out; you put the big one in. In, out, in, out, shake your fist about, you do the hokey-cokey and you turn around, that’s what it’s all about...kinda sums up the situation many folk find themselves in when attempting to endow their beloved Min with a more impressive turn of speed.

Engineering - Consistent measurements

During a recent discussion with a few overseas Mini brethren - who were experiencing various engine-related problems - something cropped up that I have always taken as granted (in the sense of ' a standard for the application'); the matter of consistency in measurements.

Now we're not talking about the sort of measurements you make with a ruler, since discrepancies of a small nature don't tend to matter a whole lot. No, we're talking about the sort of measurements made with fine measuring instruments such as micrometers or vernier calipers.

Now, the discussion that was going on was with reference to the best clearance to run between the bore and piston for a given piston type for race or street purposes. I hade quoted figures that I generally use for both situations for forged and for cast piston types.

The recent rolling road re-test of the 1275 engine build I did saw an opportunity to do some exhaust systems testing.

I had noticed a few years back that the RC40 was being manufactured by a different process than the originals - giving rise to a change in the shape of the bends applied to the system. I had wondered if they would be causing a restriction at all - but hadn't had the opportunity to test it. The lack of expected power from the aforementioned engine lead me to investigate all possible angles from the tyre contact patch to the carb mouth. I found nothing that explained the 14 or so bhp I was 'missing'. After some application of the old grey cells I mentally narrowed cause down to one of two things - either the piston oil control rings were still causing excessive drag (75% of all internal friction of an engine is generated by the piston rings) or perhaps these new bends in the venerable RC40 were indeed causing a power loss.

Articles search results for piston rings

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