Interesting ignition timing anomaly...

[Soundy]

So I was checking the ignition timing on my carb'd '87... pulled the two vacuum hoses off the advance diaphragm, plugged them, checked the idle, fired up the timing light, tweaked the distributor (was a tad retarded)... bolted it back up, and took it for a spin... felt good, power a little smoother... then I realized I'd forgotten to reconnect the vacuum lines. So I pulled over, reconnected them, and headed out again... oddly, it seemed the power band had collapsed - it seems to have a slightly better power band WITHOUT the ignition-advance line connected.

This ring any bells with anyone? Any possible explanation? Am I on drugs?

[Strugglebucket]

on the carbed engines aren't you supposed to set the timing with the vacuum advance hooked up?

[Soundy]

Nope. This is done per the shop manual procedure.

[A20A1]

You double check timing to make sure your advance diaphragm is working... but prior to that you set the base ignition timing with the advance disabled.

[Strugglebucket]

hmm, i dunno then. i've always set the timing with the advance on because that's when it's supposed to be at 15° which is what's marked on the flywheel (i only have a cheap timing light).

maybe your dizzy's phucked. was the timing stable with the light on it or did it jump around?

[Soundy]

I know the advance diaphragm is working, because when I first hooked up the timing light (bought it used, first time I've used it, wanted to make sure it was working), the engine was revving at about 1500rpm and the advance was still hooked up, and the 20-degree mark was just at the top of the window, and dropped away when I disconnected the advance.

The service manual specifically states to set ignition timing with the advance disconnected, and all timing settings are made at idle (in neutral for manual, in gear for automatic).

http://moltenimage.com/freebies/g3accord/engine_electrical/24-4.JPG