292 y-block distributor puzzler

[Stiggy]

Originally Posted by highcking

Stiggy - no. None of the reference manuals say anything about the correct vacuum readings except the reading of 6 degrees BTDC with vacuum advance shut off. But the ATDC reading may be correct anyway. In a regular system, when you check timing at idle, there may still be a small advance contributed by the centrifugal advance weights in the distributor. I’m not sure about that. There’s no obvious way to check timing under true load conditions Where manifold and ported vacuum change as soon as the engine is put under load. I’d like for others to report their vacuum reading at idle with the vacuum lines connected. I still could have a faulty unit though it seems to work ok.

Can you do a vacuum/pressure check on both of the lines going to the
vacuum advance diaphragm? Something is causing it to go to ATDC.
I've checked vacuum at idle and there is none (500 ~ 550 rpm) The timing at idle should not change when the vacuum lines are connected..