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Discussion Starter · #1 ·
Whilst setting timing on my '88, I unplugged the vacuum line from the distributor, and capped it. I set idle with a timing light, to base timing of 16* BTDC. Upon reinstalling the vacuum line, I see no change in the timing, where I was kind of expecting to see something.

Should it change? If so, what should it change to, at idle, with the vacuum hooked up? I have not disassembled the distributor to see if things move inside yet.

-adam
 

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If I'm not mistaken the vac advance should only change the timing when the engine is under low to moderate load.
 

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depends on where the vac line is connected, some cars ive seen have them connected on the non vac end of the Thottle plate.

OEM spec is 16 degrees, i like to run them around 14, it gives it some extra leway when you crank them up
 

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A 16v turbo c900 does not advance the timing at idle, or anytime else. It only retards under boost. I have heard this a few times, but I think it's just internet lies. You are good to go. Setting the timing to 14 would not be advisable, unless you are running some sort of jank tune and are just terrified that your car will explode.
 

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yes, and this is how it should be. In-fact, if you apply vacuum to the boost retard capsule, and observe a timing light you will see some timing retard... Not sure why, but take a look! It should not be connected to constant vacuum. on a standard 900-T or SPG, run premium gas and you can set the timing a bit advanced, - the high side of 16,-17.5. It will have a hair better take off, better throttle response, and theoretically a minuscule bump in MPG.
 
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