SU Carbs - Connection, HIF type

Although there are a number of different versions of the HIF type carb, they all essentially share the same type of connection layout.

The diagram below depicts the most common type - the connections can be on either the right hand side (as illustrated below) or the left hand side. Some have the connections shared on either side. Whichever, the port functions are the same. It isn't essential the crankcase breather pipe be connected - you really don't want that choking crap from the crankcase spoiling your nice, fresh, fuel-rich incoming mixture - but it's obviously essential to block the port off if you don't. A blob of RTV Silicone is sufficient in most cases. To adjuster mixture - screw the adjuster in to richen, out to weaken. There may be a 'anti-tampering' cap in there on some carbs - just hook it out.

SU Carbs - Dashpot oil

This subject is a regular message-board poser. Many of us have touted our preferences and discoveries whilst playing about over the years.

One problem with trying to deal with it on the message board is the sheer volume of information offered and available against the time availab

Classic example - the MG Metro. Its adventurously sporty cam makes for a slightly lumpy idle. This increases idle speed emissions, so Rover use manifold-sourced vacuum to increase idle speed ignition timing via the vac advance. It is a little on the thin side, but the whole engine tuning data for each engine is based on using this oil. Used as such it works very well, especially where economy is the main goal and the car is driven very sympathetically.
ATF - 'automatic transmission fluid'. A very good substitute where the genuine SU dashpot oil isn't available for use in STANDARD spec engines.

SU Carbs - HIF, a more finely honed instrument

Modern technology continually sweeps its ever-growing arm across all manufactured products and the SU was no exception. From closer scrutiny, and more demanding emissions control the HIF variant was born. So what have they done to improve it over its predecessor - the HS - and is it worth hanging out for? PROS. Integral float - the 'IF' in the new type number HIF. The previous H and HS type carbs with their side-mounted remote float bowls worked fine until used in racing where serious cornering speeds generated enough G-forces to lean-out the fuel mixture. The remedy was to fit a spacer between the float lid and float bowl to raise the fuel level held in it. OK when running, but at idle and rest, fuel would bubble out of the jet - causing bore washing, poor pick-up, and horrendously rich CO mixtures at idle! Fitting the float integral with the carb, directly below the jet hole (port/orifice), eliminated this problem. Jet temperature compensation - This was first aired on HS types

SU Carbs - Poor idle quality

Something that crops up when any modifications are made to an engine - mainly in the form of improving induction and exhaust capability - is that of idle quality.

After applying aforementioned freer-breathing products to enhance power output, many complain that no matter what - including post rolling-road tuning - they can not get a satisfactory, steady idle setting. And this after checking for manifold/gasket air leaks and spindle to carb body play (usual suspect as the spindle wears quite dramatically over several thousand miles). There is one thing that is often over-looked - the air valve found on many later model cars. This sprung-loaded air valve is built into the butterfly, sometimes called a 'poppet' valve or anti-dive valve. It is primarily there to reduce emissions when the engine is on the over-run - closed throttle at speed, i.e. anything other than at idle and gearbox in neutral.

SU Carbs - Quick reference needle selection

Since there is already a very good source of starting points/applications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased (swinging) needle example of the breed.

Unfortunately I cannot give an all-encompassing table of what needles are needed for which engine builds. My life's collection of all the automotive-orientated work I'd ever done was stolen out of my car by some low-life scum a few years back. Not for what it was - but for what it might be. All I have is a few scribbled notes, the source of where I start now. Being an oft-voiced question on the message board, I thought I'd share it with you. Since there is already a very good source of starting points/applications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased (swinging) needle example of the breed.

SU Carbs - The history

Practically every Mini owner can name the brilliant engineer responsible for our obsession. Many can name the man responsible for the rubber suspension spring.

A goodly number know a fair bit about the engine's heritage and the man who came up with the extremely efficient cylinder head design.They account for the biggest chunks of the Mini's anatomy. But what about that other extremely simple yet hugely effective instrument that features so prominently when engine tuning occurs - the SU carburetter? A limited few can tell you what 'SU' stands for, extremely few have any idea of its concept and evolution. So let's put that right… In the beginning Strangely enough, it all started way back with William Banks Skinner; one of the owners/directors of the well-known Lilly and Skinner footwear distributors.

Camshaft Design

Elgin Cams is a company that is a direct descendent of such famous California specialists as Isky, Delong, Winfield, etc. etc. Elgin has taken the art of cams into the science of the '90's. Computer designed and handcrafted workmanship guarantee a first class camshaft. Custom designed cams are a specialty. Part No Applications: CAM001, CAM002, CAM003, CAM004, CAM005, CAM006, CAM007 Elgin has made cams or sold his design to General Motors, Ford Motor Co., Nissan Corp., Zakespped International, Porsche Motor Sports, Winston Cup "Engine Builders. Elgin has the largest percentage of cams used at the SCCA Runoffs from GT-1 to Formula-V. He also has provided original or new technology for antique and vintage racers. Much information has been recorded about the four stroke internal combustion engine and yet only a small percentage of people really understand how it works and fewer people know how to modify an engine to suit their needs.

CTR-STR1057 GROUP A TURBO HEADGASKET FOR RACING, BLOCK NEEDS MODIFICATION

This gasket was originally developed by Howley Racing way back in the mid eighties for what was then part of the factory Rover Group racing effort - the Group A Metro Turbo. C-STR1057 Group A Turbo head gasket The engines developed by Howley Racing were giving 220+bhp and 185lb ft running 16.4psi boost - quite a chunk of power in a car little bigger than a Mini! Despite 10" wide sticky slicks, the engine chirped the tyres in each upward gear change. Even more impressive when you consider this was still on it's single 1.75" HIF SU carb! All that was basically done was to take a standard production head gasket (the then all over silver TAM1521 - a great gasket it it's own right) and add a reinforced fire ring by over-lapping the existing one with an extra fold of metal.As a consequence the block needs to be machined to accept this gasket - rendering it useless for any other gasket fitment and any further over-bores (even to 73.5mm) unless a top-hat type liner was used.

Cylinder Head - Unleaded Fuel Use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this. See bottom for useful part numbers. The situation not at all being helped by all sorts of conflicting information from 'leaned' sources, such as lead levels in humans has declined greatly since 1935 - despite the rapidly expanding ownership of petrol-burning vehicles. And benzene and toluene used in unleaded fuels are cancerous. Still, the powers that be are relentlessly forcing through the 'no heavy metals in fuel' bills, not being at all put off by such trivia. Not surprising bearing in mind the complete debacle on the catalytic converter front - the type decided on for world wide and universal use was developed and tested in California!

Cylinder Head - Unleaded Fuel Use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this. See bottom for useful part numbers. The situation not at all being helped by all sorts of conflicting information from 'leaned' sources, such as lead levels in humans has declined greatly since 1935 - despite the rapidly expanding ownership of petrol-burning vehicles. And benzene and toluene used in unleaded fuels are cancerous. Still, the powers that be are relentlessly forcing through the 'no heavy metals in fuel' bills, not being at all put off by such trivia. Not surprising bearing in mind the complete debacle on the catalytic converter front - the type decided on for world wide and universal use was developed and tested in California!

Engine - 1098, Initial Tuning

The 1098 (1100) engine has had a lot of bad press over the years - largely because of early experiences when trying to tune the motor brought about problems with the then standard components available - they simply were not up to taking any real punishment as experienced in racing.

See bottom for useful part numbers.

This fallacy was handed down generation to generation like some scary bedtime story. Those that have used the unit in more recent years, employing more capable componentry know what a demon motor this can be. Following is an initial look at what it will do with a little modification - the results compared directly with it's smaller brother the 998 for illustration of the potential.

Abridged History
When the Mini was first conceived it ustilised a de-stroked version of the then quite remarkable 948cc A-series engine.

Engine - 998 Tuning, Bolt-ons

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. See bottom for useful part numbers Terminology: MSC/MM - Mini Spares Centre/Mini Mania ID - Inside Diameter OD - Outside Diameter BBU - Big Bore Unit (refers to all 1275cc-based units) SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998) BHP - Brake Horse Power LCB - Long Centre Branch Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay. The single biggest restriction on any standard Mini is the 'breathing apparatus' - anything that is connected to the induction and exhaust systems. The standard exhaust being the biggest culprit - it is desperately restrictive in the name of noise suppression and cheapness of manufacture. Oddly enough it also increases fuel consumption when tested over a better designed, fre

Winter is coming.........

Cold running and why tuned Minis simply quit running when pulling up.

Winter is coming, and with it various issues that affect Minis used throughout the year, no matter what the conditions.

This month's consideration is cold running and why a plethora of tuned Minis simply quit running when pulling up. Ignoring the few that are down to various other ailments, the main issue is just the cold weather. Those that suffer more ...

Air filtration - K&N Air cleaner test.

In the forefront of Mini tuning, improving the over-all breathing capability of the very asthmatic A-series the air filter set-up is one that sees priority attention. All the widely available (and widely varying) stage one tuning kits include at the very least a replacement - and hopefully - high-flow air filter element to fit into the standard plastic case,

In the past few years (well, must be nearly 6 years by now!) since I got involved with writing for the specialist Mini Magazines I have been continually fighting with the problem of limited space. This has limited what I have been able to cover, both in subjects and in details. Up until recently (say the past year or so) I have been covering fairly broad topics in a fairly broad terms and detail. Basically trying to cover perhaps the most popular areas dabbled in by the Mini owning masses.

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.

Cylinder Head - Unleaded fuel use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this.

Cylinder Head - Unleaded fuel use

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this.

Distributor - Initial ignition timing set-up.

Any deviation away from the original standard engine specification, or where a dizzy from another source is used in the engine you have, the ignition timing will generally be different from that set by the manufacturer.

Terminology -
Dizzy - Distributor
TDC - Top Dead Centre
BTDC - Before Top Dead Centre
ATDC - After Top Dead Centre
CR - Compression Ratio

Tacho - Tachometer, rev counter (not to be confused with Mexican food delicacy!)
Vac - vacuum (pipe, unit, etc.)

Any deviation away from the original standard engine specification, or where a dizzy from another source is used in the engine you have, the ignition timing will generally be different from that set by the manufacturer.

Engine - 998 tuning, bolt-ons (stage one)

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay.

Terminology:
MSC/MM - Mini Spares Centre/Mini Mania
BBU - Big Bore Unit (refers to all 1275cc-based units)
SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998)
BHP - Brake Horse Power
CR - Compression Ratio

To improve engine out-put, you need to increase the engine's 'breathing' ability. The stage one kit deals with all the easily bolted-on external parts, and represents the best increase for investment. From here on in the power increases will cost commensurately more money.

Engine - 998 tuning, further options

Following on from the easily bolted on performance enhancing components out-lined in the stage one section, we need to consider where to go to get more power output.

Terminology:
MSC/MM - Mini Spares Centre/Mini Mania
BBU - Big Bore Unit (refers to all 1275cc-based units)
SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998)
BHP - Brake Horse Power
CR - Compression Ratio

To improve engine out-put, you need to increase the engine's 'breathing' ability. The stage one kit deals with all the easily bolted-on external parts, and represents the best increase for investment. From here on in the power increases will cost commensurately more money. Power production of any engine, once the 'breathing apparatus' (induction/exhaust system) has been dealt with to cause no restriction ...