4 replies to this topic

[JonnyAlpha]

Hi,

I have been scratching my head in the garage and thought I'd pose the question on here.

I am modifying an A Series Cylinder Head and need to make a template of the modified cylinder head chamber profile so that I can easily scribe it to the other chambers ready for grinding.

 

Here is my modified chamber:

 

It's easy enough to make a template using thin card, but I need to be able to precisely re-locate the template on the other chambers.

In Vizards book "Theory and practice of cylinder head modification" he suggests that the only reliable method of locating the template is to use the valve guides.

He shows a picture of a template and suggests making two holes that correspond to the centre distances of the valves.

 

What it doesn't show is how to achieve this and I am really struggling to some up with a method of doing this.

 

If I make the template first, how on earth do I ensure the holes for the valves are correctly located?

If I start by getting a sheet of template material and drilling two holes with centres corresponding to the valve centres, which I believe is 1.343"? How do I them transfer the template shape onto this accurately, ensuring that the valve centre holes are correctly located on the template.

Stumped......

 

[Avtovaz]

as a guess, take the valves out, put the cardboard over the top of the guides and tap it and itll cut the holes for you.

 

also then, if you put the cardboard over teh chamber and lightly tap the edge itll cut the shape of the chamber for you very accuratly

 

dont forget also the chambers arnt the same, as in they are mirrored. i made that mistake and had to scrap a head lol

Edited by Avtovaz, 13 September 2021 - 08:05 PM.

[Turbo Phil]

^^^^This.

Phil.

[JonnyAlpha]

as a guess, take the valves out, put the cardboard over the top of the guides and tap it and itll cut the holes for you.

also then, if you put the cardboard over teh chamber and lightly tap the edge itll cut the shape of the chamber for you very accuratly

dont forget also the chambers arnt the same, as in they are mirrored. i made that mistake and had to scrap a head lol

I didn’t follow this, must be tired, thinking how on earth as the valve guides are way down in the valve throats, then I realised you were talking about the other side where the springs are 🤣😂😂

[JonnyAlpha]

OK so I made the template.

Had a small piece of aluminium so I transferred the shape to that and cut it with Tin Snips and filed it.

 

 

 

You can just make out the marks in the plate for the valves.

I did this placing the template over the finished chamber, using a cylinder head gasket as a guide and taped it in place to hold it still.

I then turned the head over and put a 7mm wood drill bit down the guide hole and tapped to make a centre mark.

 

I'll drill these out later.

Edited by JonnyAlpha, 24 September 2021 - 08:43 AM.