GrahamFountain wrote: ↑Tue Jun 02, 2020 5:46 pm
The only related limiter I've heard of is that there was a centrifugal weight and spring on the back of the competition version of the rotor arm. Supposedly, that would come out and short the spark to the opposite terminal if the revs got too high. But I've never actually seen one of those. And I was only told that in answer to the question why the Sprint's rotor arm was such an odd shape.
Hi Graham, I think you are referring to one of these. This is specifically a Lotus Rev; Limiting Rotor Arm. Stamped Lucas 410299 and "1100 rpm".
The story goes that when the Lotus Elite was first imported into the USA the dockers would race them up and down the quayside. So Lotus fitted these rotor arms to stop that. The 1100 rpm is the dizzy rpm at which it triggers or 2200 rpm crankshaft speed. And as you say the spring loaded movable bit moves to the left in the photo and conducts the spark energy down to the ring which is connected underneath to the dizzy spindle and earth.
Still interested to know what engine had a Bosch distributor with a counter balanced rotor arm in 1874 CE, when Robert Bosch didn't start the company till 1886?
Graham
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.
Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).
