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Triumph Timing Cover Mod


This is something that may interest some folks or maybe not. I have in the past when building Triumph pre-unit custom bikes, out of junk of course, set up an ignition system that uses the exhaust cam from a unit model. That is ,one that carries the advance unit or ignition rotor. This moves the ignition from behind the cylinder to the side and easy access. Now to do this I have an old right side engine case of the generator variety, this allows me to do both genny and alternator types, then with a double diameter plug made that taps into the cam bush location, first removing the bush for a better fit. The other end is sized to fit the unit points seal hole. I then take a pre-unit cover and carve a chunk out of it and take a corresponding unit timing cover and cut a chunk out of it. I try to make a close fit and clean up for welding but normally fail and end up with chicken shit welding, lucky someone thought to make flap wheels for the grinder. The trick is to screw the cover pieces firmly in place to the crank case half to prevent warping with the heat of welding. It will never be real pretty as the are some height differences and the welding will make it hard to polish because of different material colours. But when cleaned up, painted, it can look pretty nice. It is a custom bike after all. Inside I use JB weld to fill any voids. This stuff holds America together. Eliminating the magneto and  going electronic ignition on a pre-unit can be expensive for that specialised body to house the new ignition. As can magneto rewinding. This is one way to reduce that cost and if a shiny cover is not an issue then this might be for you. Set and forget ignition, easy to get to, for genny models or alternator ones. When I go this way I use a twin outlet coil which fires both together, wasted spark, whether on points or electronic. A different look for that old Trumpy custom you might want to knock up from swap meet hunting. If it is a fresh build changing the exhaust cam is no biggie. Of course while you are at it one would get a seal machined into the timing cover for the crank nose to seal better and provide better oil pressure. I won’t mention a gauge.


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