Tweet
Hi Folks,
Thought I’d share what I’ve been doing in regards to a coil for my 31V Harley. The bike came with only one of those round Jap coils from the 70’s but since I’m restoring I want to go the OEM look.
I was discussing my dilemma with fellow forum member ‘downunder vl’ and he put me onto a company here in Oz that makes 6v dual lead coils and kindly donated a dead OEM unit so I have an original housing to use.
https://www.trispark.com.au/Dual-Lead-6V-Ignition-Coil
They also have a 12v version if anyone is interested.
So, after gutting and cleaning the OEM housing I started pondering and here’s what I came up with.
I got some 5/8” square steel bar, cut a piece at 4 ½” long, and using the rivet holes in the housing as a guide marked out, and drilled to 3/16”, the 4 holes to allow the rivets to pass through when reassembling.
Then using the new coil mounting holes as a guide drilled the other 2 holes (at right angles to the rivet holes) and ran a ¼” UNF tap through them.
Square Bar.jpg
Then some more measuring and I jumped on the lathe and made the 2 aluminium bushes shown in the pic below. I used aluminium because I had some. Steel, brass, plastic, anything should work just fine.
Mounted.jpg
The length I made the bushes keeps the coil from contacting the steel bar and puts the plug leads in the right spot to go straight up to the holes in the lid. But only in that plane. From the other they don’t quite line up but not to bad.
Leads to Lid.jpg
The front plug lead is too short for a VL but as they just screw in to the coil anyway I’ll change them out for OEM copies before final assembly.
Once I mounted the coil to the square bar I sat it in the OEM housing for a trial fit. As you can see there is clearance all round.
Clearance.jpg
I used 3/16” bolts through the rivet holes to hold it all together but it occurred to me that once it was rivetted back together you’d have to unsolder the top to change plug leads and the bottom as well to change out the coil as you’d need to access the bottom ¼” bolt.
So I made another length of 5/8” square bar but this time instead of drilling the 4 rivet holes to 3/16” I threaded them to 3/16”, got some 3/8” long button head cap screws and screwed 4 in from each side.
Front View.jpg
See next post for more.
Thought I’d share what I’ve been doing in regards to a coil for my 31V Harley. The bike came with only one of those round Jap coils from the 70’s but since I’m restoring I want to go the OEM look.
I was discussing my dilemma with fellow forum member ‘downunder vl’ and he put me onto a company here in Oz that makes 6v dual lead coils and kindly donated a dead OEM unit so I have an original housing to use.
https://www.trispark.com.au/Dual-Lead-6V-Ignition-Coil
They also have a 12v version if anyone is interested.
So, after gutting and cleaning the OEM housing I started pondering and here’s what I came up with.
I got some 5/8” square steel bar, cut a piece at 4 ½” long, and using the rivet holes in the housing as a guide marked out, and drilled to 3/16”, the 4 holes to allow the rivets to pass through when reassembling.
Then using the new coil mounting holes as a guide drilled the other 2 holes (at right angles to the rivet holes) and ran a ¼” UNF tap through them.
Square Bar.jpg
Then some more measuring and I jumped on the lathe and made the 2 aluminium bushes shown in the pic below. I used aluminium because I had some. Steel, brass, plastic, anything should work just fine.
Mounted.jpg
The length I made the bushes keeps the coil from contacting the steel bar and puts the plug leads in the right spot to go straight up to the holes in the lid. But only in that plane. From the other they don’t quite line up but not to bad.
Leads to Lid.jpg
The front plug lead is too short for a VL but as they just screw in to the coil anyway I’ll change them out for OEM copies before final assembly.
Once I mounted the coil to the square bar I sat it in the OEM housing for a trial fit. As you can see there is clearance all round.
Clearance.jpg
I used 3/16” bolts through the rivet holes to hold it all together but it occurred to me that once it was rivetted back together you’d have to unsolder the top to change plug leads and the bottom as well to change out the coil as you’d need to access the bottom ¼” bolt.
So I made another length of 5/8” square bar but this time instead of drilling the 4 rivet holes to 3/16” I threaded them to 3/16”, got some 3/8” long button head cap screws and screwed 4 in from each side.
Front View.jpg
See next post for more.
Comment