Timming my spider

[barnesjtsl]

1979 spider. I have a couple of posts related to an idleing issue. I have timmed this thing by ear. I have the distributor at a location where the engine sounds like it is runnig fine. As you may have seen from my other posts I can't get it to idle below 1500 rpm.

When I put my timming light on the vibration dapener I see the timming mark at about 3 inches before the gage. I can move the distributor so the mark lines up with the gage, but the engine does not run well and it will backfire through the carburetor. I have checked the compression and all the cylanders are at 120 or above.

Could I have the timming belt a couple of teeth off? I'm not the greatest mechanic in the world, but I do know a few things, but this issue is driving me crazy.

Any ideas out there?

John B

[So Cal Mark]

no surprise it won't run slower than 1500 if you have the timing that far advanced. I'd check the basics before getting crazy. Cam timing would be the first thing I'd look at

[barnesjtsl]

Could a bad vaccum advance cause this idleing porblem? I took the vaccum advance hose off and sucked on the hose (man someone could make something from that statement) and air came through the hose and nothing moved within the distirbutor. When one does this shouldn't you expect no air come through the hose, and that the "sensor" should move a little?

Is this an indication that my vaccum advance is bad?

Thanks for all the help,

John B

[racydave]

The vaccume advance module should move under a suction, and hold that suction. To set the base timing at idle( approx 800 RPM) it should not have vaccume, only when the RPMs increase.