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Discussion Starter #1
Hi,
I recently was instructed on how to change (retard and advance) timing on my car. Its so cool to finally know how to do this, and how easy it is! ( When we checked my timing it was over 15 degrees and we retarded it down to 10 degrees. Slightly noticeable decrease in low end power after this.) Anyway, my question is... what effects in general come from retarding timing and advancing timing? Which will improve gas mileage? Which will improve power? Once one changes the timing, does the mixture have to be changed as well? Thanks for any response! :)
 

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timing

Kurt;

Stock factory timing is 10 deg BTDC. This gives decent performance, good mileage, low emissions and lets you run on regular gas.

Advancing to 14 or 15 deg BTDC gives better performance. Mileage shouldn't change much, but emissions get worse and you should run high octane gas or you may get pinging/knocking due to detonation (very bad for motor).

Advancing past 15 deg probably won't improve performance, going too far (like say 20 deg) will make it worse. It will also give you worse milage, more emissions and detonation.

I run my Supras at 14-15 deg BTDC on hi-octane gas (91-94 octane).
 

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Discussion Starter #3
Hi,
A mechanic friend of a friend of mine said that the advanced timing (15 degrees instead of factory 10 degrees) would probably run less emissions. So we had advanced the timing back up to 15 at least until I can pass the emissions test. Now you are saying the opposite, but it is too late as I do not have a timing light to change my timing back down. I HOPE I will still pass, as we have already changed distributor cap, button, wires and plugs. This plus running the car hot with a fuel additive is the best I can do to pass this test. (Fingers crossed).
I DEFINITELY experienced better performance once timing was set back up to 15 degrees and NO detonation whatsoever ( I am running hitest at 93 Octane as you suggested, maybe that's why...) For my own curiousity sake, I need to verify from another source what effect advanced timing has on emissions. Thank you for your input! :)

Kurt
 
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