Building a BMC A-Series motor for street or race!

We have all seen the tremendous number of cars still being used as vintage race cars and/or street cars that still run the venerable A-Series motor that was first introduced in the late ‘50s.  These motors were used in everything from Sprites and Midgets to Morris Minors and Mini Coopers.  Many of these motors found their ways into any number of special race cars including the early Lotus 7 and many Formula Juniors.  The motors ranged in size from the first 850cc (actually 848cc) found in the 1959 Minis to the most common 1275cc as used in the later Sprites and Midgets (the last of these models actually converted to the 1500cc Triumph engine). 

So with all of these potential applications, it is easy to see why so many are always being rebuilt for street or race applications.  The simplicity of the motor not only made it so universal in it’s applications but also means that everyone that has one would like to believe that they can at least manage the rebuild process.  While some people are satisfied with simply understanding the process and will have a professional do the actual work, other at least want to identify the various upgrades options they want used.  And still a large number of people want to do all but the machine shop work themselves.  This means that information is the best tool that we all need before we attempt this ‘simple’ project.

The first step is to determine what type of owner you are going to be?  What are the pros and cons of being the total do-it-yourself person. If you have rebuilt a motor of any type in the past then it is an easy answer- have at it- these are indeed simply motors. You will indeed benefit from having the advice of someone that has done one of these motors in the past, but on the whole you only have a few technical features that could be considered unique to these motors that you might benefit from.

If you decide that while you think you know what you want as an end result but lack the desire or skill to do it your self, then researching all the books written and various Websites dedicated to this motors is your first step. Now this process could be a lengthy one if you have not previously tried to understand how to pick a camshaft, decide on carburetion, etc. etc.  Lot’s of expert advice would be a big help. 

If you really want the easy way out, contact your local builder, tell him what you intend to do with the motor and let him have at it.  But here is the first word of caution! Just because your local builder has been building Chevy motors for a gazillion years does not mean he can build even a street motor yet alone a race motor.  A few simply questions could go a long way to try to qualify your choice of engine builders.  Has he ever build a BMC A-Series motor or any British car motor?  Does he know where to source the parts he/you will need?  Under no circumstances should you entrust a race or performance motor to an engine builder that can not answer yes to all of the above question.  If you are looking for a good street motor, I would suggest that at least the shop should have worked on British motors before you entrust him to ‘try his luck’ on yours. 

If you are planning on building the motor yourself, many of the same questions apply to how you will pick a machine shop to prep your block, crank and cylinder head.  If the shop ask you for the clearance to set for the connecting rods- take it someplace else!  If the shop ask you to supply the valve seats- take it someplace else!  If the shop does not understand the tricks to line hone an inline (Sprite/Midget) block- take it someplace else!