Timing... What a subject. Two takes on it. 1 - Definitely need to find TDC. Definitely need to identify whether the timing tab is correct for that balancer. Then make the correction for what you find. If you want it "correct" and you find it has the wrong timing cover for the balancer, you will have to pull the balancer and either put a "correct" balancer, or a correct timing cover on. You can also do what the PO did and make a "different" mark.
2 - I read an article by Smokey Yunick in the early 70's. If you know anything about Smokey, you would know that he tested everything. He was constantly trying to get the most out of what he was working on. Smokey knew (from testing) that factory tolerances were all over the place. One '69 350/300 might need timing at 8 degrees, where another might be 6 degrees and another 12 degrees. Smokey recommended setting timing at the recommended setting. Then, make sure it is at Operating temp and take it for ride. Does it ping under load? Manual trans you need to put it in 4th gear going 20 mph and nail it, does it ping? Automatic, best way is to brake torque it hard, does it ping? If it pings, you need to put higher Octane gas in it and test it again. If it does not ping, you are either good, or you are leaving something on the table. Smokey recommended going up in 2 degree increments until it just started pinging and then back it down 2 degrees. Note I said "just" started pinging, then back it down 2. I have been using this process since the early 70's and I have always gotten between 2 and 6 degrees more advance, along with the added power and mileage. If your car is loud you might not be able to do this, you have to hear the ping. Obviously if you don't feel comfortable or do not know what you are doing, don't use this process. Pinging is detonation, detonation eats pistons. And this only works with non-computer cars.

My 2 cents, Dan

 

I have the same piece of chalk in my tool box from the 60's that I only use for timing marks.

 

I used to do some 'by the ear timing' when I was young, but as I got older I found I was rewarded with less sensitive hearing and it is a blessing when the noise from the passenger's seat gets objectionable. I tell her I have to turn the radio up because I forgot my hearing aids. I don't dare tell her it has to do with her singing to the oldies.
I'll use the light. and live a little longer.

 

Our own Lars from this board has a definitive paper on setting timing. I'll see if i can find it.

 

You can also read my tuning seminar, which is on this web site in a thread started by me... easy search.

Duke

 

Found it Duke. Good read. Nice job, alot of info, that took you some time.

I got a little tickle when you stated even the 30/30 cam should pull from 1000 RPM to redline. The tickle was because I was totally shocked when my 396/375 did just that. If you can handle a little story. It was a Nova, 396/375, 4 speed, 4.10 gears. I had a broken right arm. This kid wanted me to race his buddy's 396/350 Chevelle. I showed him my arm (I was shifting by reaching thru the steering wheel with my left hand because I could not pull with my right hand). He said I'll shift for you. I laughed, he kept bugging me. He wore me down... I agreed to it. I knew even with him shifting for me it would not be much of a race. I typically beat hyd. cammed stock 396's by several cars. I told him what to do, when I said NOW, shift to the next gear. Flag went down, I got him out of the hole, threw the clutch in and said NOW. Let the clutch out... He went to fourth. He shouted what do you want me to do? I said leave it. It didn't drop all the way down to 1000 rpm, but you can imagine. I kept my foot in it and still beat him by several cars. Although I am certain he was not a very good driver, he also had a 4 speed and 3.55's. I could not believe how it pulled from that far down in RPM. I had a Chevy dual point with all centrifugal advance and set at 36 degrees total. Like I said your statement made me giggle a little that you were so right.

Dan

 

Duke and those who collaborate with him are the go to guys when stuff has been messed around with for 50 years. You don't need them for absolutely original cars or cars where the owners have already listened to their advice. I used to get paid for working on these things and STILL didn't know some of the subtle stuff Duke and others have pointed out. No need to go to crazy possibilities right away until the simple stuff is checked. Our '65 had the dizzy gear on 180, a burr on the fast idle cam and the wrong vac canister. That's it and it had zero low end and way too fast an idle. Problem solved for about $15 bucks and advice from those who actually know stuff.