Fellow ZZ502 Owners -

What advance curves have worked out best for you?

Have you had luck with straight mechanical vs. direct vacuum vs. ported vacuum?

In the past I have found for best emmisions 12 Deg. initial advanced was as much as I could run, but for best idle quality and general overal performanvce 16 Deg. initial was best. I've never pushed it past 36 deg. total with straight mech. I have about 20 deg additional vacuum advance in the current Vac. pod.

Just looking for an overal consensous on the best timing curve.

Kind Regards!

Any ZZ502 owners out there?

The ZZ502 manual lists 8* BTDC initial, and Car Craft magazine's Cheap Street Chevelle ran 19* BTDC initial.

I'm just trying to get a better consensus.

Thanks!

Ported vs. manifold for the vacuum advance is a moot point IMHO..they're both the same once you open the throttle.Manifold vacuum would be used if you needed to clean up/smooth out your idle if your cam was very radical and still idled rough with alot of intial.With that in mind,I would use an adjustable vacuum advance,with 10* in it,and run it to ported..I'd go for 20* mechanical,and set your base from there..16-20* would work.And to have it all "in" by 2500-3000

this is all from memory cuz i did my timing 2 years ago. ANyways the manual stated it wanted 12 or 14 initial and thats how we set it. The car ran really poor, stuttering, sluggish, etc. SO moved it up to 18 or 20 forget but i know i have somewhere around 39 total. Hope that helps