Thx for responds, measured piston at tdc and measured .065 below deck.  Heads are ported intake and exhaust with larger exhaust valves off rectangle heads I had, don't think heads were shaved.

Closed chamber, but think with that piston only making 9:5.1 or 9

Hey guy, doing  a new build and using flat top pistons with bevel, what gasket should I use to get most compression?
Thx

WOW, that thing looks great now!

634 lift, or 643 cant recall, 115 separation, yes pump gas.

Hey GT, i can get the numbers on the cam, i got the cam from Merc through a speed shop and what they recommended, that cam they dont list cus i guess merc puts them in there off shore boats and dont want the public to accualy know what it is according to Gordys speed shop in Yuma, AZ.  Ill call and get it, thanks.

Thanks, Mr jet boat performance ( dont know your name)  I think i have to be around 550 or 600hp.  Look back at the beginning of my post and will tell you the set up im running.

GT Thanks, i can cut the impellar at old machine shop i used to work at and get it to a A size.  I dont think i would be sacraficing much to do at least that, yes my boat is big for a jet.  At one point when i had to old motor i was turning 6500rpm's with big ported head, but i also had about .165 clearance at wear ring, motor blew up, rod through pan.

Well, i think i should start by making sure the cam is dialed in  for starters.  I could be that i just dont have the HP, it is a big boat for a jet but after all the motor work i jjust thought i would have more top end.  You guys have benn a great help on many levels, i need to start with just motor timing first i think.  Ater im done with that ill  hit you guys up again, you guys been a great help and think motor tune and set up is the starting point.

Compression 10 to 1, and timing at 36 at full adv.

thanks, ya i thought i should have something protecting the impellar, i just rebuilt the motore and made many changes this time, lol.  The motor is a 454 bored 60 over, oval port heads that have been ported exauhst and intake, i also installed a bigger exauhst valve in heads,643 lift cam, rocker roller everything, air gap manifold, flat top Keith black pistons, 830 holly, Kodiac exauhst.  I dont know what the horse power is, i built the motor myself, but it pulls hard from bottom threw mid rangs that seem like it just flattens out, it tops out at 4800rpm, not sure of the speed, maybe 65. should i cut the impellar to an AB?  I dont know if the grade is trimmed at all, looks like its just bolted in, in 4 places, also i hear that that type of grade is dangerous and dont get why that is?