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porting & polishing


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Yes you can do basic work yourself.  Many years ago I worked on a Mk1 Fiesta.  If I recall correctly, I clamped an electric drill in a "Wormate" bench and connected a flexible drive shaft. I used a small grindstone to match the ports to the manifolds and smooth out the major lumps left in the ports by the casting process.  I then worked on the chambers to reduce the masking of the valves by the walls but very little metal could be removed because of the restriction imposed by the head gasket.  Finally, I contoured around the valve seats and the valves before grinding in the valves.  The head was re-assembled with a Weber DGV downdraught and a four branch exhaust.  It certainly made a big difference to the performance  but how much was due to the head work, I do not know.  Given the oppertunity I would do the same again.



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Vizard can show you how to do it:  http://www.scribd.com/doc/12986341/Tuning-Standard-Triumphs-Vizard

Many decry his opinions and mods, but they seem to do me proud.   And as he suggests. more than half the work that gives a benefit is in the inlet and exhaust ducts, niot just in the chambers.


He says, and I agree, that a drill just won't spin a stone fast enough to cut cleanly and quickly.    An air-driven die grinder will drive the tool at 14,000 plus rpm, which will also allow a burr to work.  Burrs cost more than stones but last much longer and work much quicker.


And if you do work on the chambers', it's essential thereafter to measure their volumes.    They must be the same, within 0.5mls, and only then can you know the Compression Ratio, and how much to skim off the face to compensate for the metal you have taken out, or to increase the CR.



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