MED EN40B CRANKSHAFT KIT - INLINE

Whilst standard crankshafts can be effectively re-worked to improve their counterbalance effect, it is not possible to add material, only subtract. You're also unlikely to know the history of a second-hand crankshaft - it could be over 60 years old!

Our crankshafts and conrods are manufactured just 20 minutes from MED at Arrow Precision Engineering - the very best in the business! We've worked with Arrow for over 20 years to create the best possible product.

Any inline 1275 engine block, so AH Sprite or MG Midget predominantly. A later Marina block could also be used.

We've tried both and have found no tangible difference in strength and reliability between the two manufacturing techniques. Our preference is to have crankshafts CNC machined from EN40B steel billet, as this allows for regular design development without needing to make a new forging tool each time, which would not be economically viable.

Absolutely. Each crankshaft is supplied with a test report, fully balanced, 100% crack detection and with certification of material and heat treatments. Critical detail inspection reports are also supplied. There is an incredible amount of work involved in producing, machining and testing each crankshaft, using Arrow Precision's 50-plus years of specialist experience.

There's three benefits - strength, light weight and high quality. H-section steel conrods are considerably stronger than mass-produced standard conrods, which were never designed for high performance applications. Standard conrods can be lightened and balanced, but even then our steel conrods will be lighter and stronger. The highly accurate production process allows for exact build tolerances; you will not find a higher quality A-Series conrod.

This is the length from the centre of the big end journal to the centre of the little end journal. As standard on a 1275cc A-Series this is 5.750". Changing to a longer conrod and shorter piston will maintain the same overall length, but offer a reduction in friction in the engine and give a marginally longer piston dwell time at TDC. Overall this is considered a performance improvement, but it's only useful if the race regulations allow a non-standard rod length.

Ideally upgrade the standard main caps to a four-bolt steel centre main set, yes. We consider this a must-have for any competition A-Series engine, as the three-main-bearing design of the crankshaft is particularly prone to 'whip' at high rpm.

Yes, please contact us via email or phone and we'll be happy to help further. Simply let us know what compression ratio you are aiming for, or if you're not certain, the general engine spec and usage. We can put together many different combinations to best suit your engine build plans.