MAKING YOUR AUSTIN FLY!

Our September Clubnight featured an informal discussion on making Austin Sevens go faster chaired by David Whetton who welcomed Bernard Cowley and Vince Leek.  All concerned have considerable experience in racing, hillclimbs and sprints and so the purpose of the evening was to share thoughts and knowledge on aspects of the Austin Seven when used for competition.

In terms of speed a normal Austin  could attain 45 – 50 mph with a Special doing 60mph and a racer about 90 revving between 6500 – 7500 rpm.

Engine

What can you do easily? 

• Fit a straight through flowed exhaust system.
• Fit inch and quarter SU carb  some people have inch SU as fitted on early MG and Morris Minor.
• Vince favours the use of a Colourtune to get the initial mixture right on an SU

More advanced operations include:

• The inlet manifold can be improved with a different design and polished and gas flowed.  John Barlow is one supplier of manifolds and Bernard had one made which splits the incoming mixture on a knife edge.
• Some blocks can be bored out to +80 thou or +84 if using metric pistons and rings. As a rough guide Barlow pistons are around £185 and Yamaha motorcycle rings to fit  about £100 a set.
• An air driven power file and Dremel is useful for porting.
• A Phoenix crank is essential for reliability and Bernard uses a standard splash fed which works well for short runs but Vince talked about the need for pressure feeding for racing and the fact that white metal is more forgiving than shells.  It is vital that there is plenty of opportunity for oil to flow around the big ends for cooling purposes. 

Camshaft

There was some general discussion on the aspects of camshaft design and differences between extreme racing and fast road types.  Bernard uses a fast road Newman camshaft.

Gearbox

Looking at hill climbing Bernard favoured Nippy gears and there was discussion on close ratios including Vince’s Andes box. 

Rear axle

The favourite seemed to be 5.25/1 (8/42) as used between 1932 and 1937.  

 Flywheel

The need to lighten the flywheel was about changing the speed of the engine quickly.  Bernard had a flywheel as wide as the starter ring.  2lb can safely be removed from a standard flywheel.

 Ignition

• David talked about racing on points and using Magnetronix and Bernard said he favoured the reliability of a Pertronix system from VW suppliers Machine 7.
• There was a need to have a coil to match the system together with better leads.
• We were shown adaptors to use 14mm plugs in a 18mm head and Bernard told us about an 18mm NGK offer on the internet for £14 a set.

 
Suspension

• The group discussed the weaknesses of the basic front axle and locking up one shackle seemed to be the simplest route to stability.
• There was a lot of discussion on lowering the centre of gravity with flattened springs and using upturned spring eyes also mounting the spring on top of the chassis.

 Brakes

Vince talked about using the stronger 1935 cast drums and Bernard had been fortunate to find a job lot!

Phil Whitter (acting as chief note-taker!)