Kirk Hillman wrote:
<snip>
> possible. I have a spare head to play with... any suggestions?
<snip>
If you don't make the ports any bigger, you aren't going to (affect the gas
velocities) end up any worse than an untouched head, only better.
Start with new guides if it needs it, then have valves and seats cut. Three
or five angles so that you can control the width of the seat. Whoever cuts
them should recommend you a width range (perhaps the Land-Rover book has a
dimension?), stick to the wider side of that to improve flow at low valve
lift.
Take a die grinder and make sure the valve seat matches the port, removing
as little material as possible.
Remove any casting flash from inside the ports thenselves, but nothing more.
Check manifold-head match, 'adjust' with die grinder as neccessary, but
don't go mad. A step from small (manifold) to large (port) on the inlet and
large (manifold) to small (port) on the exhaust is nowhere near as bad as a
large to small on the inlet and small to large on exhaust.
You won't make it ANY worse, and you'll certainly gain something, but how
much I have no idea.
Also - there is a sharp 90 degree edge to the combustion chambers where they
meet the 'head face' that the gasket seals against. Just take the shrapness
off of that edge, say a 0.5mm radius curve on it, which will help avoid
pre-ignition/pinking/knock/whatever its called!
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