Services for Brough Superior motorcycles and their contemporaries
KTOR engine assembly page last update: 02-2005
|Well, here I hope to present a few pictures of
the assembling. At the moment, you can have a look at the loosely assembled
crankcase, barrels and heads only, but I hope to have more pictures sometime
This is how it looks from the drive side.
Note I have already made the 8 thimbles for the cylinder head studs.
|And a view from the timing side.
|5/2004: I have pondered the question of how to make the head bolts for
quite a while. The problem is that you want them to be high tensile steel,
as they are quite stressed.
Now this alone would not be a problem, but they need to have a collar at the bottom, holding the thimble that screws into the crankcase. I understand the original ones were forged from solid, the thimble threaded over and finally a kind of nail head forged to the bottom end.
The common practice nowadays is to machine the bolt including the collar, but without the hexagon from solid, thread the thimble over it and then braze the hexagon on.
The problem with this is that you will soften your material due to the brazing, and you cannot do any heat treatment afterwards, again due to the brazed joint.
My way out of this dilemma is to use a screwed-on collar, having a 7/16*26 l.h. thread so it does not come off when you tighten the bolt. A bit of overkill maybe, but now the whole thing is made from a pre-heat-treated bar of 42MnCr4 steel, having a tensile strength of about 800 n/mm^2.
Making 8 bolts and thimbles kept me busy for more than one weekend I am afraid....
|6/2004: I have machined the intake manifold now and made two stainless
nuts for it. This alone was quite some hard work, boring out a 2" hex bar..
But making the 4 tappet guide blocks ( I have used a tough Aluminium bronze CuAl10Ni Fe) and the 4 pushrod return spring covers (stainless, of course..) took the best part of yet another weekend!
|7/04 and I have made the camshaft and breather valve bushes.
|2/2002: Meanwhile, I have had the barrel necks plated and have given the rest of them a coat of black heat resistant paint.
|And there is some progress on the top end.
|So, after all it doesn't look too bad, IMHO.
well, I am aware the engine stand is not quite up to the standard of the engine. I once made it from various leftovers, one of these things just intended as a provisional item, but made just a trifle too well to be thrown away...
|To be continued....
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