I've been working on my Goddaughter's 360 that I didn't build. Looooong story short, trying to get the timing dialed in, I found it's pretty happy at....30* initial??

That seems pretty high, and after spending too much time fiddling with swapping advance springs, I decided to measure the very-factory-looking timing marks on the balancer.

First, I wrapped a tape measure around the balancer and got roughly 22.75", which is the circumference if you do it by math: 7.25" (diameter) x 3.1416 (pi) = 22.78. So far so good.

So, if 22.75" = 360 degrees, then 2.275" = 36 degrees.

Why, then, is the 36* mark (the very bottom one) on this balancer at about 1.9"? The top of the tape is at the 0 mark, which I did verify is TDC.

Also, looking the stock timing cover, the 2 white dots are 20* apart - 10* BTDC and 10* ATDC. The 2 white lines on the balancer are supposed to be 0 and 30, but look more like about 23* or so by the timing cover marks. (Middle pic).

Another way is 22.78" (circumference) ÷ 360* = .0633" per degree. 36 degrees × .0633 = 2.27".

7.25 X 3.1416 = 22.7766". (1) degree is 0.0632683". (30) deg is 1.898049" (36) deg is 2.277" which that one is a weak 2&9/32" with your tape or cut a strip of newspaper with your calipers & use it as a ruler. As you know those (30) & 36) stampings were done by somebody (looks professional tho). & I dont remember what your earlier post said the distance was on them (from the OE TDC slit) as to wheather they are correct or not. EDIT turn the dampener a bit CW till the OE zero TDC slit (where your tape is hooked) is now at the (O) on the timing tab & measure down 1.898" & see if that is at the 30 deg slit & measure down 2.277" & see if that is at the 36 deg slit. You can measure the 2 distances you have without turning the dampener but getting the dampener TDC slit at TDC (zero) will give some clarity/make it easier especially since you have already verified that the dampener TDC slit/timing tab zero is correct. MORE EDIT if 36 deg is 2.277" & this one being marked at 1.9" then for that to be correct the dampener would have to be 6.05" diameter (1.9 divided by 2.277 then that sum times 7.25 = 6.05 dampener diameter but in the pic it looks like 7.25" (??) so it sure points to the 30 & 36 added slits being wrong but they look professionally done sooo I am at a loss but with your TDC being confirmed I would remark em. EVEN MORE EDIT I Googled & some SB chebbies use a 6" dampener (not sure about ID/shaft fitment). On to the solution: what is the dia? I would set the initial to 15 for a start then limit the total to 35 with the FBO $25 plate then work with the springs then plug in/adj the can & more on the last two later if info needed. is this a DD & stock or is it souped up? & MORE EDIT I just noticed the (0) stamped on the TDC slit right where the tape is hooked & that ain't an OE Mopar dampener.

It's pretty clear that the stamped "30" and "36" are something that was added by someone. The factory line in the thing would probably be about 30. Your math is correct and you need to re-mark the thing for your own tuning capability. If it starts right up at 30, run it. No problem there. Just get the total where you want it and you're golden. FWIW, I have a low compression, big cam 400 that starts better locked out at 34 than it does with 10 degrees of start retard.