Untouched

This is the combustion chamber for the original MG Metro head. The shape is standard, but the size of the intake valves is larger. Note the ridged, crescent-shaped casting defect along the upper right inside the intake port. That will come off.

Intake Port

Once the air/fuel mixture leaves the intake manifold, it enters here. Note the mis-match in the metal, half way and on the left. This is caused by the core being mis-matched when it was made, and that defect being molded into the head when the molten metal was poured into its form.

Inside the Intake

Looking down the intake runner, with the intake valve guide seats on each side. It is this shared design that really limits the power of the A-series engine.

Exhaust Port

Not as large as the intake port, the exhaust port exhibits the same kind of mis-match as the intake. This is not a perfect casting!

Lines

The lines that I will be cutting to are drawn in. Let the work begin!

No Turning Back

The pockets are opened up, and about half way complete. I cut into the intake seat right away, and was more careful after that! But accidents do happen...

Smoothed

A little bit of loving applied to the intake runner, via the mini grinder...

Long View

Here is the merged shot of the intake and exhuast ports. The center exhaust port is slightly larger than the ones on each end, but not significantly so.

Valve Guide Seats

Exhaust valve guide bosses for 2 and 3 are ground down to allow better flow for hot exhaust gases. This should better match 1 and 4.

Closer

Here is a closer shot of the exhaust boss. This should allow for better breathing, increasing volumetric effeciency. In theory, anyway.

PlayDoh Measures

I plugged the intake and exhuast runners with PlayDoh, flatting them off with spare valves pressed down on them. This gives me a flat surface and allows me to measure the volume of each chamber.

Done

After measurements were taken, two chambers were opened up slightly more, and here is the finished head (Photostitched, hence the odd looking image).