Rumble fish,
Brother I in no way meant that defensively. Was still drinking my coffee, was meant to be a joke but I forgot to add “ and this was my opinion, not butthole”. No I stand by what I said, the OP said he was using 360-1 heads from Indy, which are aluminum closed chamber 65cc heads if I remember. I just had to look them up to be sure because I had forgotten. Indy site even said “for use with 11:1 compression and up on large cubic inch engines pump gas or race”. Your correct on the implied question I should have been more direct. My calculations are saying either pull back duration to work with the lower compression, or up the compression to work with the cam. The heads are great so no issue there. The Dynamic compression ratio is where it’s all at, static compression ratio is just a reference point, the 12:1 SC on pump gas shouldn’t scare anyone. Similar to what the OP did with cam selection 10.5:1 with 249 at .050 is more like a DCR of 9.2-9.8:1. So if he shortens the duration it would pull his compression ratio back up closer to his static or, if he upped his compression to meet the cam that he has needs, it would accomplish the same thing and work more efficiently. So compression up, or cam down. That’s what I’m saying. Safe on pump gas 91 with those heads either way.
