"Block relief" - L.M. Williams book

[Paul N-M]

I have hesitated before contributing further to this thread, but there's now plenty of meat to chew upon.

Relieving the block. The diagram is Bill Williams' book is poor, what is required is a smooth radius, as described by Holly Birkett in 1952, so that the incoming gas doesn't stop to rub its bum which gets scraped by the sharp edge. Or something like that, as my father wrote. Definitely a good modification.

Bowdenex brakes. There have been some efforts that have introduced more friction than they should. However, given large radius curves and good cables they work well. Simplicity was so equipped in 1957 and still has them today. I do concede that installing them in a standard production body has its challenges though.

Camshafts. It's interesting that Bob thinks the Williams idea won't work. It reminds me of the bumblebee, when expert aero engineers determined that with its weight, wing area and power it couldn't possibly fly. They forgot to tell the bee though! My father reground scores, if not hundreds, of camshafts in very similar fashion. Sure, the 50 thou grind went through the hardening, but the base circle is lightly loaded any way, and though his earlier shafts were chrome-plated to restore hardness, he seldom did with later shafts, particularly those with only 25 thou off.

Bill Williams' Book. There are so many errors in it that I wonder if he wrote it, or proof-read it. I guess not. He claims to be the inventor of Bowdenex braking then describes the action totally incorrectly. I have a copy annotated by my father (who, I must admit, publicly expressed his disapproval of Bill Williams) with barely a page without comment. It was written in 1958, well after much of the  material had been published by the 750MC, written by Holly Birkett, Arthur Mallock, and many others including my father, with no acknowledgement.
As for it being the best of its kind, I guess Alan hasn't read Special Builder's Guide or the Austin Seven companion.

I also hesitated to bring in JF and others names to the discussion as it seemed obvious that most of what was being asked has been addressed in the 750MC book. I had a JF cam and followers in my second seven special which I used for trials with a modded block with a decent radius into the bore just as the book suggests and it went very well. There is plenty of solid info there and plenty enough to make your 750 sv go as RF suggests.
Some have gone further and experimented with twin plug heads and removing material from behind the valves, something that was thought to be of no benefit to getting more mixture in and only lowering the c/r even more than that already lost in doing the block. However as with so many myths I seem to remember both mods together gave almost another 1000 rpm and the additional power that came with it.

As RF alludes to his fathers 'correspondence' via the bulletin with 'reader' Williams, it makes interesting reading!

Paul N-M