Distributor woes (or operator woes?)...
 

Yesterday, I set out to go over my timing "end-to-end".
Car is a 1963 w/300hp (original block).
Distributor is setup with a B1 vacuum can: (8-degrees @ 16-18hg)
Engine pulls 15hg @600rpm.

Car is warmed up. Connected up timing light.
I started process by disconnecting can, and plugging vac line.
All vacuum hoses leak-free. I also plugged PVC inlet on carb.
I dialed in my timing light to 36-degrees.
I ran RPM on car to point cent. advance was "all-in", and timed car to 0-degrees.
I brought engine back down to 600rpm and dialed light back down to zero.
***OK...this is where things got funky****
Timing mark was reading 16-degrees....kind of high (supposed to be 6-8).
No big deal I suppose. Timing is now dialed "all-in" and the numbers are what they are.
OK, now I connect unplug vacuum line and connect the vacuum can.
I take timing reading (and verified multiple times): Vac-advance adds in 17-degrees (dialed in 17 on timing to bring mark back to 16)! That is kind of high for a B1 that is rated for just 8.

Thoughts? These numbers dont add up at all.
20 degrees mechanical advance, and rotator plate vac-mounting point is setup to double advance of any give vacuum can?

PS: Based on the symptoms I'm seeing (off-idle bucking when pulling out at low throttle...carb is fine), I thought my marks were off. So I verified TDC with the mark on the harm. balancer. TDC is fine.

1. Do you have stock springs or softer springs from a kit?
2. If you installed a spring kit, did you replace the worn out or missing nylon advance stop with the bronze stop that comes with the kits?

1. The factory 1963 distributor specs have 24* centrifugal advance at 4600 RPM so if you time the engine using the 8* initial (per the book) you would get 32* total WOT timing. You set the total WOT timing to 36* so the initial should probably fall around 12* +-. I can't explain why you read 16* initial unless your setting was a little north of 36*. If the idle speed is below 700 the centrifugal advance should not be adding to that number at idle.

2. The B1 vacuum advance control specs are in DISTRIBUTOR degrees which are 1/2 crankshaft degrees. Crankshaft * for the control are 16* @ 16-18" vacuum that's why the timing light readings double when you connect the V/A control and check things.

If you want to experiment with total timing, carefully remove the distributor springs then set your dial back to 36* and run the engine at 12-1400 RPM (fast idle) and the flyweights will be full out so you can set the timing without revving the engine so high with your hands and face in there so close. You can also set the initial prior to removing weights then remove and check/verify the centrifugal advance.

Have fun, just try to understand why your crankshaft readings are higher than you expected. Watch your hands...