Timing marks

[Doba76]

This is the timing tab on my 77 400, am I correct in assuming that the 10 and 20 on the tab are before TDC?

 

[vintage chromoly]

Yes

 

[65-440]

Absolutely

 

[Doba76]

Thanks guys, I was 99.9% sure until I saw that 440source.com said the exact opposite. Must've just been a typo.
http://store.440source.com/Factory-Timing-Cover-U-Tab-Long/productinfo/100-1061/

 

[Ranger16]

Are there any that are marked ATDC and what would be the reason?

 

[oldbee]

Ranger16- choke settings, lol...Just playing with ya, never heard of ATDC. Nothing below 0deg. I don't think(?)

 

[Doba76]

Doesn't make much sense to me either, but this is what the tab on the 400 that came out of my 76 Cordoba looks like. Also see it on a lot of older small block Chevy's. Weird.

 

[Ranger16]

I guess that answers the first part of my question.