Timing issue -- help!

[dfirestone]

Hi all -- I'm new to the forum and trying to get my 71 Z-car running right again. In tuning it up, I installed new points but now can't get the timing anywhere near right. Turning the dizzy as far as I can, I'm still 10-15 degrees after TDC. The dwell angle shows to be correct (35-41 d egrees per my shop manual). Any ideas??? Thanks!

[Arne]

Did you install a new distributor cap and/or wires? You may have the wires one place off all the way around.

[hd240z]

I am guessing the car starts and runs since you can read the timing. Is that right? I know this sounds silly, but are you sure you have the timing light connected to the #1 wire and the vacuum hose disconnected? Are you possibly using a high tech timing light which has a dial adjuster for checking total advance (not zeroed for base timing)? You could check the operation of the mechanical and vacuum advance mechanisms inside the distributor, but if they were binding up it would advance the timing not retard it as you are seeing.

Good Luck

[dfirestone]

Thanks, guys -- and I think the problem must lie inside the distributor. I replaced the cap and rotor, the wires are only a year old, and all the wires are attached to the correct plugs. My timing light is low-tech inductive, the same one I've used for years, and I removed and plugged the vacuum hose before checking the timing. The timing is actually advanced, not retarded, and I can't retard it down to TDC, much less 5 degrees BTDC.

Any more thoughts?

[Arne]

Go back to low tech. Manually set the engine to TDC, take off the cap and see where the rotor is pointing. Turn the dizzy so that it should fire about there, then put on the cap loosely and see which plug wire the rotor is pointing towards. Verify that the plug wires are correct on the cap this way.

Here's a thought, you didn't mention this, but have you had the oil pump off?

[dfirestone]

No, oil pump hasn't been off. I like the "low tech" approach you suggest -- I'll try it this evening.

[hd240z]

The low tech check for the vacuum advance is to remove the cap and pull a vacuum on the diaphragm and see if the mounting plate holding the points moves smoothly about 1/4" where the advance attaches and springs back when the vacuum is released.

The mechanical (centrifugal) advance can be checked by twisting the rotor counterclockwise. It should also move about 1/4" at the outer end and spring back when released. The springs and weights are located under the mounting plate which makes them difficult to inspect without disassembling the distributor.

Good Luck