Posted by Glen on 9/14/2007, 5:48 pm, in reply to "ignition timing" --Previous Message--
70.149.105.177
More important than initial idle setting is the actual curve including full advance. There are 2 different types of vacuum controls. First is the traditional advance that advances slightly as vacuum increases. The other actually retards the timing using manifold vacuum, & when the throttle is opened & manifold vacuum decreases, it will allow the timing to advance. Vacuum controls are largely emmission control related anyhow...
The real advance is mechanical & is controlled by spring loaded counterweights down under the breaker plate.
Now what you need to do is first check & make sure that the vacuum control pipe is hooked up to the correct fitting, carb or manifold, depending what is fitted. Then run it up with a timing light on it & check it at 500 rpm increments up to 4k or so & get an idea what the curve is. Vacuum controls aside, most engines want 5-10 degrees @ idle & mid-30s full +/-.
See how yours compares.
Also if the cam/crank aren't timed properly, it will screw up the timing requirements but I don't want to go there unless we have to...
HTH
Glen
: I've just put my 69 GT6+ on the road
: after a long and painful rebuild,
: and am having issues with (I
: think)the timing. The car is
: completely stock. Idle timing for an
: emmission-controlled GT6+ is 6deg
: ATDC. Basically, getting underway,
: the engine just tries to stall for a
: couple of seconds, then gets up
: enough courage to continue pulling.
: I checked the vacuum advance with a
: vacuum pump, and there seems to be
: effect on the timing with vacuum. If
: I advance the timing quite a bit
: (about 10-15 BTDC) the car seems to
: run much better. I would like to
: drive the car while I try to fix
: this problem, but am not sure if
: this will damage the engine. Any
: responses based on actual experience
: or well-intentioned opinion are
: equally welcome. Thanks.
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