Prestolite Distributor Springs?

[694spd]

After abandoning the Pertronix conversion due to the problems with mounting it correctly. I decided to just reinstall the dual points. I thought I would bench check both the vacuum and mechanical advance systems. I found that the vacuum actuated between 7 "hg and is fully advanced at 14"hg. When I tried to actuate the mechanical advance by hand. I found that it did not move as it was gummed up by dried grease. I now had to disassemble the distributor to clean out the old grease.
Anyway, I was looking at the advance springs and wondering if these were the factory springs? I noticed the the heavy spring due to its large loop does not come into play until the advance has almost reached the end of it's full travel. Any opinions on what you see in the pictures...

 

[halifaxhops]

It is factory correct, The big loop is there to come into play at full mechanical advance.

 

[RedFish]

That loop on the heavy spring lets that weight travel with the other weight on smaller spring. Prevents one spring from working against the other.

 

[694spd]

The FSM says that this distributor has the following advance curve:
1' to 6.5' @ 550 RPM
9.5' to 11.5' @ 900 RPM
12' to 14' @ 1800 RPM
I'm assuming that the 12' to 14' @ 1800 RPM would be right near the end of the travel of the slot where the heave spring starts to stretch?
Also do you double these degree numbers to get the crank degree numbers?

 

[halifaxhops]

yes, it should state that in the FSM I would think. The advance cam has a number on it that is the total mechanical degrees,

 

[halifaxhops]

I just looked at the pic, it is a aftermarket cam by ac in that, should have a number on it cannot see because of the glare.

 

[pishta]

the light plus heavy spring gives you a "hop out" curve, advance ramps up quickly using light spring, then slows down when acting on heavy spring. So its not linear. like this: