23-10-2024, 06:40 PM
A little while ago, I obtained a Mag engine and gearbox that had been used in a sea going boat. The engine was complete with magneto and dynamo, but was seized solid. Apparently it had been cooled by sea water! I assumed it was an engine that had been removed from a car and adapted for boat use. Everything on the engine had been painted green, which I thought odd. It transpires that Austin 7 marine engines were painted green by the factory.
Anyway, the cylinder block, head and pistons where beyond salvaging, but the conrods, crank and front gears are exceptionally good.
On the Magneto, there is an automatic ignition advance mechanism, the like of which I have never seen before. The mag is A Lucas Model SR4 type Mk IIA 10 57 Lucas number 42290D. I assume the original Magneto was replaced around 1957.
I started stripping the Mag, and found a slotted screw central to the main nut securing the mag' drive gear. Whist attempting to remove the said screw, it snapped off at the head. Having continued and got the drive gear and advance mechanism of the front of the mag, I then removed the rotor with the view of drilling out the broken screw. Centre popped the shaft, and started to drill out the remains of the broken screw. To my surprise the broken screw screwed itself out!. It turns out to be a left hand thread of 3/16th BSF.
After this long winded introduction, does anyone know where I can obtain a replacement L/H thread 3/16 BSF Screw?
Another oddity I noticed, The dynamo has a toothed cog sticking out of it's end, a form of REV Counter Drive perhaps?
I do not know how to load a picture of the ignition advance mechanism on to this page
Anyway, the cylinder block, head and pistons where beyond salvaging, but the conrods, crank and front gears are exceptionally good.
On the Magneto, there is an automatic ignition advance mechanism, the like of which I have never seen before. The mag is A Lucas Model SR4 type Mk IIA 10 57 Lucas number 42290D. I assume the original Magneto was replaced around 1957.
I started stripping the Mag, and found a slotted screw central to the main nut securing the mag' drive gear. Whist attempting to remove the said screw, it snapped off at the head. Having continued and got the drive gear and advance mechanism of the front of the mag, I then removed the rotor with the view of drilling out the broken screw. Centre popped the shaft, and started to drill out the remains of the broken screw. To my surprise the broken screw screwed itself out!. It turns out to be a left hand thread of 3/16th BSF.
After this long winded introduction, does anyone know where I can obtain a replacement L/H thread 3/16 BSF Screw?
Another oddity I noticed, The dynamo has a toothed cog sticking out of it's end, a form of REV Counter Drive perhaps?
I do not know how to load a picture of the ignition advance mechanism on to this page
