Road vs Track: Choosing the Right MED A-Series Camshaft

Choosing between road and track: the MED A-Series camshaft range

Our A-Series camshaft range spans civilised road profiles through to full-race specification, machined from high quality cross-drilled steel blanks by Piper Cams. This guide works through the range as a road-versus-track selector, using engine size, intended use and the accompanying valvetrain options. You can browse the full range in the Camshafts collection.

Start with your engine size

• 850 engines: standard Mini 850 engines do not use camshaft bearings, so the block must be line-bored and bearings fitted to run one of these cams.
• 998/1098 small-bore engines:small-bore engines work better with a more conservative camshaft profile (less lift and duration) than the 1275. So if you are considering the RS profile for a 998, you may prefer the HT; as a general rule, step down one profile when building a small-bore engine, as the change is more pronounced.

• 1275 engines:ideally suited to any one of the MED profiles, depending on your desired powerband, usage and fuel type.

Road use: profiles and staged kits

The MED A-Series fast road camshafts offer three road-developed profiles: MED HT (256/256 duration, power band 1000-6000 rpm) for daily driving and mile-munching, MED RS (270/284, 1250-6500 rpm) as the fast-road compromise, and MED XT (280/280, 2500-7250 rpm) for track-day use.

As a rough guide, on an identical 1380cc high-performance road engine with a modified head, re-worked crankshaft, single HIF44 carburettor and 1.5:1 roller rockers, expect peak outputs of 100 lb.ft/100 bhp for HT, 100 lb.ft/106 bhp for RS and 100 lb.ft/112 bhp for XT.

The MED camshaft kits bundle the camshaft with the supporting hardware, and make a good option if you're starting on a fresh build:

• MED ST1 camshaft kit: camshaft, chilled iron follower set, lock tab, steel-backed oil pump and timing disc. Profile choices include HT, RS, XT, MPi and T3, with variants for 1275 and 998/1098 engines.
• MED ST2 camshaft kit: everything in Stage 1 plus double valve springs and a steel/alloy vernier duplex timing kit. Designed for the 1275 engine; a 998/1098 option is available and MED can supply an oil pump to suit.
• MED ST3 camshaft kit with 1.5 rockers: everything in Stage 2 plus 1.5:1 roller-tip rockers. Designed specifically for the 1275 engine.
• MED ST3 camshaft kit with 1.3 rockers: as above, but with 1.3 roller rockers. There's options for 998 and 1275 engines.
• MED ST4 camshaft kit: a full-race version of the Stage 3 kit, with more race-orientated camshaft profiles and uprated followers, springs and rockers.

Injection/carb style and fuelling

• Carburettor engines: the HT, RS and XT profiles were developed for carburetted A-Series engines; the FIA+ race profile suits larger H6 or Weber 45DCOE carburettors.
• Multi-point injection (MPi) Minis: the MED MPi profile (252/264 duration, power band 1500-6500 rpm) is designed for fast-road multi-point injection Minis, available in the ST1, ST2 and ST3 kits.
• Single-point injection (SPi) Minis: we would suggest an HT profile with 1.5 rockers, or RS and 1.3 rockers; any more and the ECU will struggle with fuelling and emissions.
• Forced induction: the MED T3 profile (264/276 duration with reduced valve overlap) is a special forced-induction camshaft with extended duration on the exhaust, also available in the ST1, ST2 and ST3 kits.

Track and race: competition profiles

The MED A-Series race camshafts are ni-tempered competition cams developed over decades of competition engine building. The 5-port profiles are MED 310SP (310 duration, 0.420" lift, a highly popular race cam), MED 320SP (320 duration, 0.420" lift, slightly more aggressive), MED FIA+ (296/312 duration, 0.400" lift, a historic cam for larger H6 or Weber 45DCOE carburettors) and MED STR930 (300 duration, Mini Miglia profile).

The 310SP, 320SP and FIA15+ are 'scatter' cams, with re-phased timing on cylinders two and three that MED's race testing has found highly effective on long-duration cams thanks to the unusual nature of the five-port head. Separate 8-port profiles (MED 8-PORT1, 8-PORT2 and 8-PORT3, 300 to 320 duration) cover road/rally through full-race specification.

For a complete competition assembly, the MED ST4 full race kit pairs a race camshaft (XT, 310SP, 320SP, FIA+ or STR930) with race-spec chilled iron followers, racing double valve springs, a steel/alloy duplex timing kit (optional cambelt upgrade) and 1.5:1 LDX race roller rockers.

Note that a race cam in a road-going engine is not recommended: the long duration and high lift suit engines capable of high RPM, and on a road A-Series the powerband will be severely limited by the smaller ports in the head and the lower RPM potential of a standard crankshaft. Unless the engine and cylinder head are equally racy, it will not work well.

Expected valvetrain requirements

• Valve springs: uprated road double valve spring sets are highly recommended with the road profiles to remove the chance of valve bounce at higher RPM; the race profiles need MED's race double valve springs.
• Cam timing: adjustable cam timing is essential; without adjusting the timing to suit the new profile you cannot optimise performance. MED recommends an adjustable vernier timing kit, which the ST2 kit and above include.
• Rockers: MED's profiles are all optimised to work below 1.5:1 rockers, and 1.5:1s usually give more power through increased valve lift, but there is no one-size-fits-all and some applications benefit more from 1.3:1 rockers, which can also help reduce emissions on a '90s Mini, for example.
• Followers: chilled iron follower sets come with the staged kits; the ST4 kit upgrades to race-spec lightweight followers with oil lubrication holes.

Compatibility caveats

• The road cams and 5-port race cams fit all BMC A-Series and A-plus engines, with the exception of eight-port head conversions.
• The 8-port cam profiles only work with the Arden 8-port head, where the inlet and exhaust valves are re-ordered and the cam profile is completely different.
• Standard 850 engines do not use camshaft bearings, so the block must be line-bored and bearings fitted.
• The ST3 kit's 1.5:1 rockers will not suit a 998/1098 cylinder head unless you have converted to a 1275 cylinder head and pocketed the block for valve clearance; its camshaft also does not suit late Rover MPi Minis (1996-2000).
• The ST4 kit is designed specifically for the 1275cc engine, as the LDX rocker spacing only suits a 1275-type head. It also suits original large-bore Cooper S engines, but you may need to drill and tap the block for the later-type oil pump if this has not already been done.

Quick selector

Next steps

Still deciding? Browse the full range in the Camshafts collection, or get in touch for application-specific advice.