Marine Cam recomendation 489 BBC

[rewguy]

I'm starting w a mark IV block btw.

[Walter R. Malik]

9.4-1 compression, 781 ovals bowl blended w 2.19/1.81 valves, weiand stealth intake manifold, Has factory Mercruiser log manifolds. I'm aware that the camshaft cant be too large for water reversion. Want as much torque and power as possible on 89 octane fuel. Hyd roller retrofit is the goal.

I have used several in customer engines of this type and I prefer the Lunati #20110711
272 / 280 @ SAE - 221 / 229 @.050" - 143 / 148 @.200" - .575"/.575" theoretical valve lift - 112 Separation; 106 intake centerline.

[rewguy]

9.4-1 compression, 781 ovals bowl blended w 2.19/1.81 valves, weiand stealth intake manifold, Has factory Mercruiser log manifolds. I'm aware that the camshaft cant be too large for water reversion. Want as much torque and power as possible on 89 octane fuel. Hyd roller retrofit is the goal.

I have used several in customer engines of this type and I prefer the Lunati #20110711
272 / 280 @ SAE - 221 / 229 @.050" - 143 / 148 @.200" - .575"/.575" theoretical valve lift - 112 Separation; 106 intake centerline.

did you ever dyno?

[Walter R. Malik]

9.4-1 compression, 781 ovals bowl blended w 2.19/1.81 valves, weiand stealth intake manifold, Has factory Mercruiser log manifolds. I'm aware that the camshaft cant be too large for water reversion. Want as much torque and power as possible on 89 octane fuel. Hyd roller retrofit is the goal.

I have used several in customer engines of this type and I prefer the Lunati #20110711
272 / 280 @ SAE - 221 / 229 @.050" - 143 / 148 @.200" - .575"/.575" theoretical valve lift - 112 Separation; 106 intake centerline.

did you ever dyno?

The dynomometer merely reports WIDE OPEN THROTTLE power. In the boat, out on the Great Lakes actually running it allows a much better indication of ALL the merits.

[In-Tech]

Looks like everyone is in similar ballparks on the cam. Like Walter said, even a boat doesn't spend its' life at WOT, mannerisms around the dock and clean part throttle driveability can make or break a boat being fun. I posted what I use since I've literally used that grind over 100 times. Just for fun I even had that cam idle at 300 rpm, had a chop to it that low but in general idles like a stocker at 700 and still works well with merc ex manifolds.

The specs I didn't post are .544" lift(1.7) and 222/226@ .050 and I mainly posted the recommendation to assure you that you should be able to exceed your goal easily without any undue strain on the valvetrain.

Good Luck with your project.

[Newold1]

Is the boat running the stock Bravo hub underwater exhaust or is he using a Captains Call type switchable system? If he is using the switchable system with all the good cam spec. suggestions given here he will be leaving about 25HP on the water without getting rid of those old log exhaust manifolds and running a good aftermarket marine header system. How do I know that, way to much experience with marine performance engines both on the dyno and in the water.

[Walter R. Malik]

Is the boat running the stock Bravo hub underwater exhaust or is he using a Captains Call type switchable system? If he is using the switchable system with all the good cam spec. suggestions given here he will be leaving about 25HP on the water without getting rid of those old log exhaust manifolds and running a good aftermarket marine header system. How do I know that, way to much experience with marine performance engines both on the dyno and in the water.

Unless it is meant to sometimes race somewhere ... the "Fun Factor" of the boat and the power adaptability to almost every situation is MUCH MORE important to most people than outright Wide Open Throttle horsepower.

[user-23911]

The dynomometer merely reports WIDE OPEN THROTTLE power.

It depends on who's doing the dyno job.

It's quite easy to do a dyno a part throttle, it's the normal way when doing emissions testing.

[Walter R. Malik]

The dynomometer merely reports WIDE OPEN THROTTLE power.

It depends on who's doing the dyno job.

It's quite easy to do a dyno a part throttle, it's the normal way when doing emissions testing.

Of course it CAN but, that has nothing to do with what the OP was interested in knowing here.

It is plain to see that you are simply attempting to be a troll here, like in almost every thread you make a comment, and to create some kind of argument in the thread.
Do you have anything productive to offer ...?

[user-23911]

So anyone who disagrees is a troll?

The dynomometer merely reports WIDE OPEN THROTTLE power.

But it doesn't.............does it?

[Walter R. Malik]

So anyone who disagrees is a troll?

The dynomometer merely reports WIDE OPEN THROTTLE power.

But it doesn't.............does it?

YEP ... just as I thought. You have nothing constructive to say in the context of this thread and just want to begin some kind of argument.

Ain't gonna happen.

[Warp Speed]

If the tune is proper, what ever cam works in the intended usage of stock manifolds ect, the one that makes the most WOT power, will also run the best at part theottle.

[Walter R. Malik]

If the tune is proper, what ever cam works in the intended usage of stock manifolds ect, the one that makes the most WOT power, will also run the best at part throttle.

The point is ... Power output at any throttle is NOT the main purpose for what this situation requires.

A cam which is around 235 @.050" might make a bit more power at 2,000 RPM wide open throttle than a cam with 220 @.050" but, will NOT have near the same amount of useful properties showing how the engine actually performs while going through a no wake zone or, pulling skiers out of the water or, simply cruising across the lake to a beach, concerned about how much fuel is being used. Power output is only ONE criteria which is to be considered and satisfied.
POWER output is not the "be all, end all" need for most applications yet those unknowing keep going there as if it is.

[Warp Speed]

Speed talk or? Lol
He obviously has goals, and I think most cams listed would meet those goals within the given constraints. It's not hard to keep it smooth, with proper tuning, just off idle.
Otherwise, maybe suggest a pontoon boat with a 4 stroke outboard? Lol

[andyf]

The cam that Chevy puts in the 502 crate engine would probably work pretty well in this type of application. It is fairly small, 210/220 range hyd roller. If it was me I'd keep the cam on the small side in order to enjoy the boat 95% of the time rather than overcam it and enjoy it only 5% of the time.