I enjoyed reading this. I bet they put the feed hole at the top so
that the oil would flow downwards and reach the bottom via gravity.
Did you notice how small the single oil feed hole is at the top of the
cyl head? I have a shaft with plenty of wear pattern at the bottom as
you describe but I think the rocker shafts last for a very long time.
The key is to support the shaft on both ends so that it won't bend or
break. I too have a new hardened shaft to experiment with. Not sure
but I have a hunch that chroming it could possibly make the shaft more
brittle or, if it ever did flex slightly, could the chrome plating
possibly flake and find its way into the oil system?
~Steve
On Oct 26, 2009, at 11:06 PM, Greg & Alison Blake wrote:
> While disassembling the 5th rocker shaft I have ever disassembled in
> my
> life this evening I had one of these moments where I question why
> things
> are the way they are. This time it is all centered on the fact that
> all
> 5 that I have taken apart show extreme wear on the bottom of the
> shaft,
> but minimal to no wear on the top. I am sure many of you are familiar
> with the wear pattern. These look to be the result of the bushings
> cutting into the shaft and it makes sense that they occur on the
> bottom
> because that is the loaded side of bearing surface. The oil feed
> holes
> in the shaft are located between the bushings on the top side of the
> shaft which line up with the holes in the rocker arms I assume to
> splash
> some oil onto the valve tips. Why didn't they use oil holes on the
> bottom of the shafts to lubricate the critical bearing surface? Has
> anyone tried this?
>
> The new shaft that I have on the bench waiting assembly is one of the
> readily available harden shafts. Does it make sense to get that hard
> chrome platted as well? Anyone have a good resource for that service?
>
> Probably over thinking this simple assembly. Rollers would be nice.
>
> Greg
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