Mercury 280 head

[Esox4130]

Is 38 cc the tightest head can run on pump gas on a 280? Buying billet heads and want to make sure get right chambers for boating. Thanks.

[eli]

Steve ,I'm running 34.5 c.c on pump 91 would think 38 could run 89 octain

[superboattwin250]

You have to remember the exhaust port timing on a 280 is lower than the 260s and stock they make 150-155psi. I wouldn't go any tighter on the crappy pump gas in my opinion.