Will Delco-Remy centrifugal advance springs work in a MP distributor?

Bill Crowell said
Status update and bump-up on this Mallory YH distributor thread.

I've got the centrifugal advance slots set at about halfway, with one black and one blue spring. The detonation is all gone now, running on common 91 octane gas with ethanol! I'm very happy about that.

But this engine has a fairly large cam and compression, so it seems to want a lot of advance. I got the best idle with about 30 degrees of static timing cranked in! (I backed it off to about 12 degrees for test purposes, though.)

The problem is that right now the power is very modest, and I've got to set the curb idle up so high in order to keep it running that it's not idling through the idle circuit, so the idle mixture screws don't do too much. So obviously I need to advance the static timing so I can back off on the curb idle, get the carb mixture screws working and then make some more test runs.

halifaxhops told me to adjust the advance slots, and I surely don't want to disrespect my mentor in any way, but what do the rest of you guys think? Should I try static timing first, or go ahead and give it more static and more centrifugal right away? Please let me know what you think.

Not sure what half the slot is in degrees but I think you have way too much mechanical advance. I have a Mallory YH on the test bench right now, and the springs never do what the papers say they should do, and the adjustment sticks are off too.

I don’t want to go back and see exactly what you are tuning on, but you should be at 18-20 degrees initial if you have a small block. That means you only need 10-11 degrees mechanical. That ain’t much. And I would use the stiffest springs you can find and see if you can keep the curve advancing to at least 3500.

The other option (which is near impossible unless you get some custom springs or make something work) is to open the mechanical advance all they way up, set the initial to 20 and get enough spring on it that it advances all the way to max RPM. Set the total at as close to peak torque as you can and send it. But you have to keep an eye on the plugs and make sure you don’t run into detonation. This is the correct way to do it, especially if you have an ignition system that retards with RPM, and most do.

For a big block the process is the same, but the total will as a rule be higher.

Any time you can get the curve to advance to max RPM you will make more power. The issue is getting that done.