MattBMiller

I'm helping my buddy put together a motor right now and need some input on cam selection. The motor is a Gen V 454/330, 8.75:1, built on a balanced bottom end, ported 781 oval ports, air gap intake, Edelbrock 750 and lightning headers. Not looking to spin more than 5000 rpms because of the bottom end.

I need to get a cam installed for him so I can get this motor wrapped up and get to my own motor.

Thanks!

SB

iTrader: (1)

HR or Flat Tappet ?

What kind/size boat ?

Oh, are the heads already assembled ? If so, do you have all the spring info along with it's installed height and what the heads retainer to guide clearance is ?

Donzi502

225 @ 50 with 550 lift on a 114 lobe seperation and install it at 110 centerline. Add a little to these numbers for the exaust or take alittle off for the intakeif you think t to much. Un shroud the intake valve as well. You need about 120 pound on the seat and run Roller rockers and a real good timing set with German Ewis chain. Lunati 73-815 springs are a good cheep spring that will do the job. Keep plenty of oil on the springs as well. Oil restrictors cause mary hell to the springs in our race boat, they get to hot and die after 10 hours. She will run hard. 55 pound oil preasure at 5000 rpm hot. Use Kendals racing oil 20-50. Jas

KAAMA

iTrader: (1)

A hydraulic cam somewhere right around 218*/226* at .050" lift on 110* lift .515"/.515" lobes should put you at right around 5000rpm or so. I would try and do a hydraulic roller if you can swing the $$$.

My cousin did a Merc 330hp upgrade and he ran a flat tappet like this in his 461cid engines with some junk oval port heads that JimV intalled larger valves (2.19"/1.85") and did some bowl/pocket port work, unshrouded the valves, dual plane intakes, 830cfm Holley, 8.6 comp ratio, 32* of timing, stock Merc Thunderbolt ignition/distributor and it made 461hp @5100rpm.....torque was something like 510 ft lbs @ 3600rpm and stayed FLAT up to 5100rpm on Tom Earhart's dyno with dyno headers.

My cousin's boat is a 32' Baja with GIL dry exhaust and so far he picked up 10mph MINIMUM just in the midrange alone and about 70mph on top so far---still testing props.

Whiteknuckle

The engine you are building is very similar to mine. Mine started as a Mark IV 330 HP. I am running 9.0:1 compression, 049 heads with the big valves installed, an air gap manifold with 800 CFM Holley, Lightning Headers, with a few other up grades here and there. I had Bob Madera of Marine Kinetics pick my cam and I could not be more pleased. He delivered just what I asked for. 465 HP @4800 RPM, 530 ft lbs torque on Katechs dyno. Torque curve is amazingly flat. Take the guess work out of it and work with Bob.

Another suggestion for you is to go with a roller if you can afford it. I wipped out an Ultradyne after about 100 hours causing the need for this build. Like a dumb ass I put in another flat tappet. I should have learned my lesson and went for the roller. Now I have to take incredible precautions with this flat tappet.
Good Luck

KAAMA

iTrader: (1)

Ditto on "RMbuilder"/Bob Madara of Marine Kinetics---he's helped a lot of people on here with cam selections. Also, I keep forgetting to mention that bore notching the block is a good thing to do on a 454. It's a very inexpensive way to get about another 30hp or so,.....BUT you have to find someone who KNOWS how to do it properly and is willing to do it....might take about an hour or so.

MattBMiller

I doubt he'll spring for a roller setup on this motor after I sent him overbudget on some other goodies.

The heads are still at the machine shop so springs have not yet been installed. We went 2.19 & 1.88 valves.


Matt