Chances are that no matter how far you retard the timing to avoid pinging, it would still ping at part-throttle. Also, it would probably run-on when you tried to shut it off. My opinion is no, you can't run 87 octane fuel in a 12 to 1 engine.
Another Opinion:
The above seems about right to me. 12 to 1 is up there for a 350, pretty much into the racing engine territory. You'll probably need to find some high octane fuel to operate at that compression ratio, and if it's an EFI engine, you'll need to find a way to get the computer to work with you.
Also, check with the emissions requirements in your state. Oxides of nitrogen will be off the chart with 12 to 1.
YES. That is a direct bolt on with no problems. The heads will bolt on, but the compression ratio will be different. Depending on which heads and which pistons, the compression ratio could be a lot different.
8.5 to 1 compression is factory stock.
10.5-1
Compression ratio on a 1974 Chevy 350 in a Nova was 8.5:1.
They did not make a 400 sb Chevy in 1974. But from 1975 to 1980 they did and the answer to your question is 8.5:1 from 1975 to 1977 Then from 1977 to 1980 it was 8.3:1 ratio. That is Advertised compression ratio. I may stand corrected on the date when I said they did not make a 400SB. But The info. I gave you was all I could find. NEUTZ.
8.3:1 is stock
The compression ratio of a 350 Chevy engine usually ranges from 8.0 and 9.0 to 1. This provides a good balance of fuel economy and power.
9:1.
with higher compression pistons
Need to know what size engine it has to answer correctly.
6 to 8 degrees advanced. for stock compression ratio.
Yes they will, but 305 heads have a smaller combustion chamber so it may raise your compression ratio.