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Home Motorcycle Home Triumph Home Export Home Norton Info Home Contact Us! Special Parts Updated 04/03/24 Customer Combat Build Oct 23 Updated 04/22/24 Blue 69S Updated 04/16/24 1975 Norton Wiring Updated 04/24/24 Combat 5 Updated 04/04/24 Roadster 850 Updated 04/03/24 1974 Norton Wiring Updated 04/25/24 High Mileage 850 Delivered 03/26/24 Mk3 Engine & Gearbox Delivered 03/07/23 1974 Norton 850 Commando Rebuild Sold 01/12/21 Updated 06/10/21 1973 Customer BasketCase Build Delivered 07/15/22 1972 Norton 750 Commando Rebuild Completed 05/15/19 First Place Norton 05/16/19 Sold 01/01/20 1972 Norton Wiring Updated 04/03/24 Customer Combat and 69S Builds Closed 10/18/23		Thursday, April 25, 2024
	While rebuilding the 1974 850, I ran into a problem. I wanted to use new Tri-Spark coils and new Andover Norton (AN) plug wires. I couldn't get the plug wire on the mounted coils. So, I took the coils off, put the wires on, and tried to reinstall the coils. There no way they would fit as they interfered badly with the top nut to the exhaust valve cover. After much investigation and study, I have come to some conclusions. But first, look thought the pictures and comments below. In these two pictures, the original Lucas coil is on the left and the Tri-Spark coil is on the right. The original Lucas coil's overall length is 4.568" and the Tri-Spark coil's overall length is 4.437". For a Norton, the Tri-Spark coil is better in that regard. But notice that the coil wire output is nearer the edge on the Lucas coil. That makes the Lucas coil a better choice. You'll see why later. In the next two pictures, the coil is Lucas. The top picture is with a OEM wire and the second is with an AN wire. The OEM wire is acceptable but the AN wire is not usable. Notice the the coil is twisted as high as I can get it and the wire still touches the nut. On a recently finished 750, it's close with the AN wires, but just barely acceptable. The 750 seems to have slightly more room. The 750, like this 850 has brand new vernier isolastic mounts. In the next two pictures, the coil is Tri-Spark. The top picture is with a OEM wire and the second is with an AN wire. The OEM wire is acceptable but the AN wire is not usable and even worse than the Lucas coil. Notice that the coil is twisted as high as I can get it and the wire still presses on the nut. In the next two pictures, the coil is Lucas and the reflector has been removed since this allows the coils to move about 1/8" away from the engine. The top picture is with an OEM wire and it is fine. The second is with an AN wire and it is barely acceptable. I don't want to eliminate the reflector so I made a bracket from 16ga steel to move the reflector forward and slightly down. It clears the tank, doesn't look out of place, and no longer limits the coils. I've been really bothered by two things: 1) The 750 Combat I rebuilt earlier this year has acceptable clearance. I finally did enough measuring to confirm to myself that the 750 head sits slightly further back and down. 2) My 1974 850 has no problem and there's decent clearance. I verified with the previos owner that the isolastics have never been apart from new. I'm sure when I get around to putting the verniers in it, I will find that the rubbers are collapsed on the bottom. So, although I love Andover Norton and Tri-Spark products, the combination of Tri-Spark Coils, AN plug wires, and 850 Nortons does not work.

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