"Block relief" - L.M. Williams book

[Alan]

Chris is dead right. The real skill in building fast A7 engines is not in getting the power, it’s in making them hang together once you’ve got it.

[Bob Culver]

The Williams book was written when Sevens were cheap and expendable. Many cars were everyday transport and  young owners were desperate for power to keep reasonable pace with traffic. Preservation of the original was not a factor.
Diagrams and considerable else in Wiliams are dubious. The camshaft exactly as diagram duplicated could not operate, and is way through hardening. 
The sv Ford V8 had tilted valves so the chamber had to be formed part in the block.
With revs,  rods bored different, gaskets, disasters, pistons can rise further than normal.

[JonE]

to be honest, Chris, if the thing blew up in an orgasmic rush of revs as a result of fitting this new bit that is bought, paid for and in my hands, it might draw my mind temporarily away from the constant penury of fault after fault with crappy old bits breaking, leaking or whatever. Bring it on! Cinderella will go to the ball!
Just that it might move under its own steam will be a plus.
(but, as I said, the slight reduction of CR for me would be a blessing.. and it also removes another potential water leak joint!)

Whether the Ricardo effect is at right angles to the force of the piston or benefiting from a slightly wider take, I'm past caring really... its going on, and I'll probably do some relief too just to see what happens! :-)

[Chris KC]

I know how you feel Jon, I was getting a bit twitchy after my own had been off the road for four years!

[Alan]

The Williams book was written when Sevens were cheap and expendable. Many cars were everyday transport and  young owners were desperate for power to keep reasonable pace with traffic. Preservation of the original was not a factor.
Diagrams and considerable else in Wiliams are dubious. The camshaft exactly as diagram duplicated could not operate, and is way through hardening. 
The sv Ford V8 had tilted valves so the chamber had to be formed part in the block.
With revs,  rods bored different, gaskets, disasters, pistons can rise further than normal.

Bob, I think you are a little harsh in your opinion of LM Williams. 
LMW was a pre-war tuner of 7s and a good one at that. He certainly had the respect of Austin’s competition department as various interesting bits were provided and his cars were invited to run with the Works team on more than one occasion. 
As for his book, it was aimed at the young special builder who did not necessarily have much technical knowledge. I admit it has suggestions that we wouldn’t do now, but in its time and for years after, it was as good as you could get. In fact, I’d still recommend it above all other books on this subject. 
I’m really interested in your camshaft comments, because I did one just like that, years ago, when you couldn’t get anything better. It did work, and it didn’t matter that the base circle went through the hardening. It lasted for years.

[Paul N-M]

Was reading about the removal of one edge of the block around each bore to enable transition of top of piston area into valve area on the later and sports heads. It doesn't give details of depth you take away, but presumably even a mm or so would be effective.

Is this still something any of you do? Or is it seen as damaging blocks which might be re-used for LC where it wouldn't be useful?

Hi Jon,
Just reading this tread for the first time. A good place to look for info on this is the H.A.M.B. JallopyJournal forum. being American there is lots of discussion re modding 'flatheads'.

Paul

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Was reading about the removal of one edge of the block around each bore to enable transition of top of piston area into valve area on the later and sports heads. It doesn't give details of depth you take away, but presumably even a mm or so would be effective.

Is this still something any of you do? Or is it seen as damaging blocks which might be re-used for LC where it wouldn't be useful?

Hi Jon,
Just reading this tread for the first time. A good place to look for info on this is the H.A.M.B. JallopyJournal forum. being American there is lots of discussion re modding 'flatheads'.

Paul

Also should have mentioned the Hot Rod Network especially the 'Truth about Ford flatheads, myths exposed' article.
All very interesting.

Paul

[Bob Culver]

Hi Alan

Worded primarily for others!
(Effects of valve clearance and follower radius ignored.)
The valves lift as soon as the cam departs from the base circle. As drawn the Williams book shows the flanks unaltered except between the new and original base circle surfaces. The two new short tangents (or steeper) from new to old base circle when extended represent a very small included angle (15 deg as drawn, and can be less, or negative!?) and hence a mighty long opening (opening in crank degrees is double(180 – cam included angle). Gives huge duration much with less than .050 lift. (Usually duration is the result of pursuit of generous opening; duration unaccompanied by significant lift is not normally an advantage, and certainly not in a road car. Too much and will barely run)
The new cam form should retain a tangent to the original nose circle, or at least to well up the flank, to avoid duration without significant lift.

For decades the Williams book was about the only info available for those outside UK Clubs. Still an interesting read but not ideal in the hands of many of todays relatively inexperienced newcomers. (It advocates Bowdenex brakes now generally dismissed. And convex big ends. Removal of rib from inlet port etc. Some time ago a whole page of ”errors” was published, and that did not include the few I had noticed!) It fosters the hot up mentality which is now not so appropriate for many cars.

[Ritchie Wilson]

In the acknowledgements at the beginning of Mr William's book he thanks PJ Stephens. I've always assumed that this is a reference to the block "relief" diagrams which Mr Stephens showed in his book "Building and Racing My "750"'. Mr Stephens says that he gained this information from the classic "How to Hop Up Ford and Mercury V8 Engines" written by Roger Huntington and published by Floyd Clymer - which is, I think, still in print.
Another well known author, JH Haynes, has a diagram for block relief in his (I suppose) first book "How to Build Austin Specials".

[Jamie]

..... It advocates Bowdenex brakes now generally dismissed. ..........

Why? I thought that the general idea was still sound.

Jamie.

[Alan]

I think you are missing the point, Bob. Whilst mathematically you are absolutely right, you have to remember that in the 1950s UK there wasn’t a cam grinder on every street corner. What there was was a lot of special builders who were, in all probability, doing an engineering apprenticeship somewhere. With a decent lathe and a toolpost grinder it was perfectly possible to do a base circle regrind in a lunchtime or when the foreman and health and safety man weren’t watching. That’s how I did mine, and ok it had little at low revs but it revved it’s little socks off. That’s the sort of person the Williams book was aimed at. Ok we have got older wiser and have more money, and we might not do things that way any more, but I still maintain it’s the best book around.
Students of American flathead V8s should add VTwins to their reading list. Harley Davidson extracted more power from side valves than almost anyone.