Distributor timing issues

[Backfoot100]

Got one that I've personally never seen before so I thought I would run it past the Brainiacs here.

My 86 Sub is pretty much a stock 350 except for headers and true duals. It runs really well after I did a fresh carb rebuild with a Cliff Ruggles kit and a complete tune up.
My problem is that I can't adjust the timing. I can loosen and move the distributor when it's cold but after it warms to operating temp, it's frozen solid. It won't budge.
The timing is set somewhere around 12-14 BTDC. At least as close as I can estimate. The timing marks don't go that high. The vacuum and mechanical advances both are free and appear to be working fine. I also have a new VC1853 vacuum advance that I want to install as recommended by Rich Weyand in the pinned Ignition Timing thread from this forum. Unfortunately, that would really be tough to do if I can't time it.

It would just be nice to play around with the timing to see if I can get it to run any better than it is already.
Any of you guys ever hear of anything like this?
Thanks in advance.

 

[Backfoot100]

So I played around with this thing a little bit more.
I changed out the vacuum can to the new VC1853 and figured I would have a limited amount of time to try setting the timing.
I had my vacuum gauge and timing light already setup and ready to go before starting it.
I started it cold and was able to adjust the timing for about three minutes before it seized up and I couldn't move the dizzy anymore.

I was able to verify that the way I was reading the timing marks was correct and it was indeed somewhere between 12 and 14 BTDC. Then I set the timing for the highest vacuum reading before it seized. Ironically enough now it looks as though its at least 16 degrees BTDC.

It warmed up good and I took it for a drive. It seemed to have a noticeably stronger off idle holeshot without pinging. I got into the secondaries a couple times and still got no pinging but the throttle response was definitely improved. It wasn't a long drive at all so I'll have to beat on it a little more before rendering final judgement but I like what I felt so far.

For a pretty much bone stock, old school 350 in a big ol' girl like this I must say that I'm impressed but I'll definitely keep you guys updated.