The first is a modified piston-ring compressor. With standard piston rings, normally a compressor is not necessary, but with the thin rings fitted on some pistons (1mm, 1,5mm and 3mm rather than 1.5mm, 2mm and 4mm) I have found that breakages are possible - especially with the very fragile oil control rings. You will see that the compressor has been cut (ground actually) to match the angle of the vee.
The cutter is used for widening the valve clearance pockets in pistons when larger valves are fitted. It is made from a spare valve, of a suitable size of course with the aid of an angle grinder. It is easy to use: just insert in the guide, mount the head onto the engine with a couple of dowel bolts and with a battery drill apply rotation and very gentle pressure. Less than 30 seconds is usually plenty to provide a new pocket in exactly the right place. There is not normally any need to deepen the pocket. It is a good idea to smear a little grease to catch the small amount of swarf created, so that it may be collected afterwards.
One problem might be to find a suitable valve to make the cutter. I was lucky: I found a 40mm valve with the necessary 7mm stem. Most modern 7mm stem valves are for four-valves-per-cylinder engines and tend to be too small.
2 comments:
Cheers Paul, clever stuff, as usual :)
Michael Beattie
Thanks Michael
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