I have a .30 over gen 5 454, with 9;1 pistons, 502 rec. port heads, air gap intake, 750 carb, powerflow exhaust, in a 265 Baja Force. Blew coupler, while engine out, thinking of installing following cam;

UPC:
021174010886
Cam Style:
Hydraulic flat tappet
Basic Operating RPM Range:
3,000-6,000
Intake Duration at 050 inch Lift:
236
Exhaust Duration at 050 inch Lift:
246
Duration at 050 inch Lift:
236 int./246 exh.
Advertised Intake Duration:
296
Advertised Exhaust Duration:
306
Advertised Duration:
296 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:
0.553 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:
0.571 in.
Valve Lift with Factory Rocker Arm Ratio:
0.553 int./0.571 exh.
Lobe Separation (degrees):
114
Computer-Controlled Compatible:
No
Grind Number:
H-296-2
What do you think??

What kind of tips is on the polwer flow exhaust? That is a lot of duration "236 int./246 exh" unless you are dumping the water at the tips.
I would never install a flat tappet cam, spend the extra coin and buy a roller cam setup.
A bigger carb would also help.

need to know at least what exhaust you have before we can direct you.for what its worth,,get yourself a roller set up.

Rex Marine Powertorque exhaust, looks like Hardin setup.

IMWO with the stock rectangular heads and your setup ,I think you will be happier with about 10 degrees less duration at .050 and not quite as much lift. If you go flat tappet and pay attention to proper break-in ,it'll live .I agree HR is preferable but not necessary on moderate cams

Better choice flat tappet cam is Crane #134241 (#134242 cam kit with lifters)
I used one in my 454mag with Imco exhaust. Pulled strong to 5400rpms.

What would be negative effects of the larger cam ? Reversion ? Do you think the smaller cam would have better performance ? Boat will currently do 50 @ 4500 wot, with a Mirage 21, 3 blade. I am adding Gill Exhaust, and thinking about the cam. Engine is out to replace coupler. Asking because I already have the larger cam with a set of Howards lifters.
Appreciate your thoughts,
Thanks,
Dale

What are the specs on the current cam ? the new cam you are looking at may raise the power band to high for your motor to reach it without running a smaller prop.

You need closer to 10:1 compression for that cam. And whatever everyone else said/will say baout exhaust. LOL.

I have been on a few Force 265's and the ones that run strong where the 502 465hp engines and up.

Weak low and midrange torque,and it won't make good power in a 454 until 5500+rpms.