Starter Solenoid

[Dennis Nelson]

I have owned my second TR3A for 2 years, and it always started after a significant number of cranks, until the valves were done six months ago.  Then starting became both a mystery and an adventure.  In the winter, when cold, it took a lot of cranking of the starter motor to get it going, but occasionally it would start instantly (a new feature), and occasionally it would start just as I released the starter button.  Lots of tuning occured.  With the passage of time and the heat of summer, starting when the engine was hot became almost impossible, causing far more stress than I need.  Cranking off and on for 5 minutes and getting it to start was a good thing a week ago.  Just days before that I had to leave it for an hour to get it to go.

 

In hindsight it all makes sense, but all the mechanics at my shop were stumped.  Valves were adjusted, mixtures richened, timing adjusted and all for naught.  At the shop this morning I mentioned that last night it had done one of its instant starts during my testing.  And it did one of those start as the thumb comes off the starter button tricks.  Ludvick mentioned that in 1968 a new solenoid came out that allows the current to the coil to be separate from the current to the starter.  We decided to experiment and put a used ($20) solenoid on and ran some wire, and the problem was cured.  And why was it worst when the engine was hot, the fan was running.  Even with the best battery in the world, we weren't getting enough juice to the plugs when the starter motor cranked.

 

So if your engine has to crank fairly hard to start, think about a better engineered solenoid before working too hard on the other approaches.  It might just be the answer.