lets revisit timing
Yes welding the inside moves the weights outward in their initial position. This results in a little more initial spring tension. But that difference in spring tension is small and within the range it can be easily adjusted.
Whether its better to weld the inside or the outer end depends on the original distributor's advance curve.
You may have noticed I try not to say one or the other is always better. This is because which is better it depends on the springs in the distributor and whatever other springs you have available to work with.
However, when starting with an early to mid smog era distributor, most of the time its better to weld the inside.
1. The retarded initial timing used on CAP/CAS distributors was offset by super fast mechanical advance. Welding the inside pretty much is all that's need to convert the distrributor to a pre-emissions curve.
A good example of the change can be seen in the 1967 440 Hi performance package since it was sold with CAP in California and non-CAP elsewhere.
Take any similar CAP/CAS timing curve, weld up the inside and then initial can be set the same as pre-emissions.
Below is the timing range for the 1968 440's with CAP. Weld the inside, and set the initial for 12.5*. Done.
Lets compare this to reducing the advance by stopping the weights by welding or blocking the outer end of the slots
With points and no vacuum advance, this could be a winning set up at the drag strip.
The timing advances very quickly and then acts something like a locked unit.
We kind of saw that in the dynomation example with locked timing above - and many of us know its what was frequently done back in the day.
Using the '68 440 as an example.
There are two drawbacks to doing this.
1. For street use (or endurace racing) it's too quick and too much timing to work with vacuum advance. Instead of having 50* at 3000 rpm cruise, now its 50* from 1200 rpm up with light throttle.
2. With any electronics dependent ignition, the actual timing seen by the engine at high rpm is retarded. See my earlier post with the videos by yellow rose and William Baldwin.
Nope. Doesn't make sense.
Yes welding the inside moves the weights outward in their initial position. This results in a little more initial spring tension. But that difference in spring tension is small and within the range it can be easily adjusted.
Whether its better to weld the inside or the outer end depends on the original distributor's advance curve.
You may have noticed I try not to say one or the other is always better. This is because which is better it depends on the springs in the distributor and whatever other springs you have available to work with.
However, when starting with an early to mid smog era distributor, most of the time its better to weld the inside.
1. The retarded initial timing used on CAP/CAS distributors was offset by super fast mechanical advance. Welding the inside pretty much is all that's need to convert the distrributor to a pre-emissions curve.
A good example of the change can be seen in the 1967 440 Hi performance package since it was sold with CAP in California and non-CAP elsewhere.
Take any similar CAP/CAS timing curve, weld up the inside and then initial can be set the same as pre-emissions.
Below is the timing range for the 1968 440's with CAP. Weld the inside, and set the initial for 12.5*. Done.
Lets compare this to reducing the advance by stopping the weights by welding or blocking the outer end of the slots
With points and no vacuum advance, this could be a winning set up at the drag strip.
The timing advances very quickly and then acts something like a locked unit.
We kind of saw that in the dynomation example with locked timing above - and many of us know its what was frequently done back in the day.
Using the '68 440 as an example.
There are two drawbacks to doing this.
1. For street use (or endurace racing) it's too quick and too much timing to work with vacuum advance. Instead of having 50* at 3000 rpm cruise, now its 50* from 1200 rpm up with light throttle.
2. With any electronics dependent ignition, the actual timing seen by the engine at high rpm is retarded. See my earlier post with the videos by yellow rose and William Baldwin.