Jerry Gilliam
Member
Interesting article in Progressive Farmer in April 2011(this months) issue. Page 36. Ask the Mechanic, Steve Thompson) says to use 87 octane in these older motors as it will explode quicker. The article was based on a question concerning a 656 gas. That would mean it was a 263 engine. Just so happens I have one along with a 460 with a 221 engine. I've always used 87 with the exception of a few times and had good luck. I have read here several times that they must run on hi octane. He also says not to use octane booster as this will slow down burn, which you do not want. Now go figure.
JW
JW