On this day Daniel Richmond (below) of Downton Engineering writes to Bill Appleby of BMC.
4th March 1963
Thank you for your kind letter dated 19th February relating to our most recent conversation regarding the development of the 12A185 cylinder head and please accept my apologies for not replying sooner. I agree entirely with your point of view , but I do still feel that the initial production of the revised cylinder head should go ahead , albeit with your proposed new number of AEG163 and still including the revisions that we have devised and subsequently tested.
I still also maintain that the exhaust valves for the new cylinder head should be reduced to 1 – 5/32″ to give greater reliability for production use . I am aware that you have already accumulated a large stock of these items and that the company would ultimately wish to use this stock , even extending that use to the cylinder head production proposed for the later part of the year, however, this could prove troublesome for production engines as we have indeed experienced to this date. I will leave this thought with you.
On this same subject , I thought that I should inform you that we are in the process of further tests with the prototype AEG163 heads in our workshops and indeed I will be able to test one of the two that we have on one of our own cars very soon. We have found that , for high performance applications , this cylinder head can also be adapted for use with the 997 cc cars that we have re-worked to give a capacity of 1088cc.
This has necessitated , among other more obvious alterations , valve clearance pockets machined into the top of the cylinders to allow for the larger valve sizes and their differing layout , the results of which are quite remarkable. We will be testing one of our works cars with this configuration in the next few months and I will forward you my report following our proposed participation in the next Targa Florio in early May.