1BIGJIM

iTrader: (1)

I rebuilt my 330HP last year. Tried for 9:1 compression. Added a fresh set of 781 large oval port heads, Edlebrock carb and intake. Cam listed below. IMCO Power Flow Exhaust. Gained absolutely no additional RPM. I checked compression before I pulled the engine last fall, 150 PSI on all cylinders. That did not sound very high to me so I thought about the cam. I talked to Dennis Moore and he said that should be a good choice. In his book he states this is the largest cam that should be used in a marine engine. What gives? To big for my little combo?
COMP 11-242-3
Gross lift 515 520
Duration at .050 224intake 230 exhaust
Lobe Separation 110
I degreed cam ia at 106 center line like suggested.
New valve springs with valve job

1BIGJIM

iTrader: (1)

Any comments from any of you cam experts

RichardCranium572

Needs more cam and more cylinder head The changes you made are not much above stock, truly need to check AFR as it could be going rich on the top end reducing power too.

PatriYacht

What rpm did it used to run? What kind of boat is it in? It should be a torque engine but it will be all over by 5000 rpm.

1BIGJIM

iTrader: (1)

It ran 4900 to 5000 RPM. Boat is a 22' Pachanga

PatriYacht

You can always try more propellor and see if it'll pull it. I would expect it to be a little faster.

Vinny P

I would not have picked that cam soley for the lobe seperation. 110* is too tight for wet exhausts. Too much of a chance of reversion. 150 psi is a good compression number for that combo. I am sure you are losing compression with the small lobe seperation.