02-01-2018, 04:27 PM
It is essential to use a good crankshaft if you are building an A7 engine. For road use and modest competition, I would stick to a splash fed 1 5/16" crank (others might disagree!)
A set of good standard Austin con rods will be okay for general use but you will need to keep the revs down to about 5000. The white metal bearings need to be done properly. A set of special forged con rods will set you back about the same as a new crank but will allow higher revs and greater peace of mind.
Good racing type pistons are readily available from the specialist A7 suppliers.
I think the budget of £5K is realistic for a moderately tuned unblown engine.
It isn't all about power, for a road car you want plenty of low down torque. I favour standard size valves, modest fettling of the ports, a trials spec cam and an SU carb on a long inlet manifold. I am sure others will disagree!
Gearing is more important than engine power. For a road car a 5.25:1 axle ratio (the easiest to obtain) and 19" wheels works well. Money spent on a close ratio gearbox is money well spent.
If you are building a special, keep the weight down. Some of the sexy looking single seaters are quite heavy. A simple Ulster body is readily available and can be very light.
As this thread is about costs, I should point out that I am a Yorkshireman with some Scottish blood! I did my own upholstery for about £150 and brush painted the car for less than £100. This reduced the pain of building a decent engine!
A set of good standard Austin con rods will be okay for general use but you will need to keep the revs down to about 5000. The white metal bearings need to be done properly. A set of special forged con rods will set you back about the same as a new crank but will allow higher revs and greater peace of mind.
Good racing type pistons are readily available from the specialist A7 suppliers.
I think the budget of £5K is realistic for a moderately tuned unblown engine.
It isn't all about power, for a road car you want plenty of low down torque. I favour standard size valves, modest fettling of the ports, a trials spec cam and an SU carb on a long inlet manifold. I am sure others will disagree!
Gearing is more important than engine power. For a road car a 5.25:1 axle ratio (the easiest to obtain) and 19" wheels works well. Money spent on a close ratio gearbox is money well spent.
If you are building a special, keep the weight down. Some of the sexy looking single seaters are quite heavy. A simple Ulster body is readily available and can be very light.
As this thread is about costs, I should point out that I am a Yorkshireman with some Scottish blood! I did my own upholstery for about £150 and brush painted the car for less than £100. This reduced the pain of building a decent engine!