Cylinder Head Combustion Chamber Template

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I agree, Martin … ‘though I did assume that William already knew [or was soon to confirm] the separation, when he wrote:

… centres corresponding to the valve centres, which I believe is 1.343"

MichaelG.

So I made a cardboard template of the finished chamber and scribed this onto some scrap ali sheeting, then cut it with tin snips.

Then after cleaning up the edges I place a head gasket on the head and taped the template in position. Next I turned it over and transferred the valve guide holes using a 7mm wood drill. These have a centre point so it seemed logical. Next I'll drill the 7mm holes for the valves.

You could have drilled a couple holes in your template well oversize and close enough to the valve centres, then make a couple of "penny" washers which fitted the valve stems exactly. Place your template carefully in the valve chamber, apply epoxy adhesive to the penny washers and position the washers over the oversized holes and drop your valves (With oily stems) through the penny washers and let it all harden off.

Bob

Not drilled the holes yet so I may just do that

If you have some gash vales you could use them?

Clean the faces, place in the valve guides, add glue to the faces.

Position your template and then turn the head over so the valves sit on the template whilst the glue sets

Dave

Dave S is about right.

The simple way would be to do it as Dave suggests but simply glue the valves to a sheet, cutting out later after transferring the required outline to the sheet. KISS principle at work?

Trying to do it after cutting out the shape is wasted energy.

Clearly needs two making.

… if you really must ignore Mr Vizard’s illustration and make your template non-flippable.

What was that about keeping it simple ?

MichaelG.

I hope that head will get skimmed, it looks rather like it's been used as a boat anchor and then sandblasted.

TBH it’s better not to glue the valves to the template as you say.

This was bought as a scrap head (cost me £15 post), should have seen it before I cleaned it up. The idea was to use thins for practice.

Once the template was made it would be a simple matter to use a transfer punch or drill bit through the valve guides to mark the hole locations.