Machining for cam..

General Chat About Exhaust, Cylinder Heads, Fuel Systems And Intake

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sidecar
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Post by sidecar »

CastleMGBV8 wrote:Pete,

Yes it seems a good idea to raise the height of the valve stems to get the geometry/relationship of the rocker tip and top of the valve correct.

I was going to have the pillars machined by 50-60 thou. but fitting the lash caps seems a much simpler and probably better solution and then shorten the adjustables to get the preload in the right area with just final teaking to get the preload where it should be, say 20-25thou.

At the moment the valve gear is standard but with heavy duty tubular pushrods and I needed 50thou of shims to get the preload to 35thou which is obviously not very good.

I will need a pushrod finished length of approx 7.975" standard seem to be 8.050"

Do you see any problem with doing what I'm now suggesting.


Kevin.
That all seems quite reasonable to me although the valve caps may add some weight. (I've never seen them, so it could be hardly anything)

I got my heads machined where the pedestals sit, I think I had 1.5mm off them, it was about 95 quid!.....How much are the caps?

The machine shop reckoned that they could have done the pedstals for less money even though "Des" reckons this is a bit naughty.

One thing for sure is that the geometry is not that good even when everything is totally standard. You can tell this by looking at the wear pattern on the rocker pads.

I did spend an hour or so filing out the outer pushrod holes in the heads as it looked a bit tight! I did not really just want to bung a drill down the hole, I ovalized them.

Er, I think we are a couple of hyjackers! :lol:

Pete


CastleMGBV8
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Post by CastleMGBV8 »

Pete,

Yes we have hijacked the thread, but it's all relevent to the original question and possibly helpful to others.

It's the work that often gets overlooked at the end of a build or conversion and you just wan't to get the car on the road, I know because I did it on my present engine and have never been happy knowing it wasn't properly set up valve gear geometry wise.

The lash caps are £30 a set so that, the cost of a set of adjustables a length checker and the cost of maching the adjustables, probably about £40 at my local machine shop should cover it and it will be well worth it in my view for the peace of mind of knowing it's properly built.

I also like the fact that the lash caps increase the surface area that the rocker tips run on.

Looking forward to getting it up and running and then I can start worrying about installing the EFI!

Regards,

Kevin.
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