total advance ?

cudavert said

I've never been a big fan of vacuum adv either.......it seems like that part throttle cruising (like up a gradual hill) is exactly when it will like to ping.....drives me crazy. I always thought most cars I've dealt with liked more initial than the factory recommended anyway. Somewhere I saw an article on how they showed people how to limit the total mechanical advance by welding on some tabs on the weights and then slowly grinding them down......it's sort of a foggy memory of it. Anybody see that?

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If the distributor is set up properly you won't have part throttle detonation issues. When you start changing, initial, total and rate you will also need to adjust the vacuum advance.

Just cranking in more initial will give you too much total. The biggest contributor to how much initial timing an engine wants is the overlap in the cam (more overlap more timing). The head design is the biggest contributor to what the engine wants to see for total. Modern highly efficient cylinder head designs are using less than 30 degrees of total these days.

For max power and efficiency you want the spark to occur at the point that you get maximum cylinder pressure approximately 20 degrees ATDC.

Stock timing curves are a compromise to protect the engine against detonation by operates not using the proper gas or lugging the engine. So they can be dialed in for more performance and efficiency.