Why are my distributor cap terminals burnt?
23 - 24* advance is probably correct as your measured advance seem to to agree with the instructions.
The advance stopping at 3400 rpm would be great. I kindof don't beleive it. But maybe the blue springs you have are different than the ones I got. I would have expected a quicker advance. Either way with two equal springs it is a fairly straight line. If anything it starts a little slow and then rises faster. Thats due to the mechanism's design, not the springs.
Before: Initial of 22* at 750 rpm, Timing using 2 blue springs, limited to 24* advance.
Same as above but initial of 14* at 750 rpm.
The timing is probably in this range now.
38* at 3400 is not out of line for a iron headed big block. Yes the factory curve is more conservative. They had to cover all situations including pulling loads up steep mountains and things like that.
38* at 2600 rpm I think may be a problem when vacuum advance is connected. Its going to add up to a little more timing than it will really like in that rpm range. There's a reason that the factory slowed the advance above 1400 rpm. It wasn't needed or wanted. The engine gets more efficient and the flame grows faster from those rpms up.
Anyway. I'd leave the advance limit at its present setting. If you change it changes the spring tensions and I don't see the need at this point.
If your spring kit has some heavier springs with longer loops, you could try replacing one of the blue springs with a one of the longer looped springs.
Longer looped spring are the bottom row.
Goal is for the spring to have just a little bit of slack with the weights at rest (all the way in).
This spring should do nothing until the weights have moved out a few degrees. It creates the second stage of a shaped advance.
However this leaves just one spring responsible for holding the weights from moving outward at idle rpm.
I'm not sure a single blue spring will have enough tension to do that. If the weights move outward at say 600 rpm, then the timing around 750 rpm will not be the initial - it will be intial plus a several degrees advance.
So if using a long looped secondary spring, probably will need to combine that with a stronger primary spring. Assuming its the same Mallory springs as I've bought, I'd try Brown.
23 - 24* advance is probably correct as your measured advance seem to to agree with the instructions.
The advance stopping at 3400 rpm would be great. I kindof don't beleive it. But maybe the blue springs you have are different than the ones I got. I would have expected a quicker advance. Either way with two equal springs it is a fairly straight line. If anything it starts a little slow and then rises faster. Thats due to the mechanism's design, not the springs.
Before: Initial of 22* at 750 rpm, Timing using 2 blue springs, limited to 24* advance.
Same as above but initial of 14* at 750 rpm.
The timing is probably in this range now.
38* at 3400 is not out of line for a iron headed big block. Yes the factory curve is more conservative. They had to cover all situations including pulling loads up steep mountains and things like that.
38* at 2600 rpm I think may be a problem when vacuum advance is connected. Its going to add up to a little more timing than it will really like in that rpm range. There's a reason that the factory slowed the advance above 1400 rpm. It wasn't needed or wanted. The engine gets more efficient and the flame grows faster from those rpms up.
Anyway. I'd leave the advance limit at its present setting. If you change it changes the spring tensions and I don't see the need at this point.
If your spring kit has some heavier springs with longer loops, you could try replacing one of the blue springs with a one of the longer looped springs.
Longer looped spring are the bottom row.
Goal is for the spring to have just a little bit of slack with the weights at rest (all the way in).
This spring should do nothing until the weights have moved out a few degrees. It creates the second stage of a shaped advance.
However this leaves just one spring responsible for holding the weights from moving outward at idle rpm.
I'm not sure a single blue spring will have enough tension to do that. If the weights move outward at say 600 rpm, then the timing around 750 rpm will not be the initial - it will be intial plus a several degrees advance.
So if using a long looped secondary spring, probably will need to combine that with a stronger primary spring. Assuming its the same Mallory springs as I've bought, I'd try Brown.