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TR4/4A Distributor problem

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carpecursusII

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OK, I recently purchased a distributor from Jeff at Advanced. My 4A was running with a 40480 dizzy (TR3), I got the proper 40795 dizzy from Jeff. He said set it 10-14 degrees at idle and I did my best to do that. The car ran fantastic for about 100 miles, then problems. It started to have a subtle miss and highway speed and coming up through second gear, then it got progressively worse to where the car would barely run. I initially suspected coil so I replaced it, no change. I suspected fuel because I think I mistakenly purchased fuel with 10% ethanol blend but the car has run thousands of miles before with blended fuel. On a hunch I pulled the old dizzy out and reinstalled it, timed, and drove. Ran fantastic, no miss.

When using a light, it appears that the dizzy from Jeff is not holding advance, I can see the mark dancing around about an inch along the circumference of the pulley when I bring the car up 2000-3000 rpm, at idle it moves 1/4-3/8 inch. With the old dizzy the mark moves around maybe a 1/4 of an inch or less at idle, and about the same movement as rpm increases, it is not rock solid but better than the new unit. I took apart the old unit and the plate shows 15 degrees stamped on it, I happen to have a spare set of springs around so I replaced them and noticed that the spring I removed were not the same tension.

So why does the new dizzy not work properly, I did check the weights and they move freely and the springs are not broken.
 
Jeff probably "recurved" the new distributer which basically means he changed the springs. Just because 15degrees is stamped does not mean it has not been altered. Its just a hole that can be made larger. Each degree is .048" on the crank. Are you sure you started where the recurved unit should be? Were you supposed to set it statically at 10-14 or running with a timing light? The real question is what happened after it was running fine and then started running poorly.
 
The 15 degree mark was on the old unit. The new unit from Jeff has 10 degrees stamped on the weight. I set the timing for the new unit at idle as instructed by Jeff.
 
+1 on calling Jeff to discuss this. As above, I'm sure he'll stand behind his work.
 
The symptoms sound like burned points or a failing condenser. As they burn, the strength of the spark gets weaker and weaker. I don't think the bouncing of the advance is causing a miss...but a mis can easily cause the bouncing.
 
+1 on the points possibility. If the cam follower has worn down prematurely, the gap would get smaller and smaller, and eventually not open at all. Been there, done that.

Just a thought.
Tom
 
and you replaced the condenser - still no improvement?
 
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