New camshaft, break-in

Since the engine isn't in the boat, it sounds like you want to run it on the cradle it's sitting on and hope that whatever water you can supply is enough at 2000 unloaded rpm or so for 20 minutes.

I you're worried about it, I think I'd start it on the stand to make sure it starts right up and has no oil or water leaks that show up right away , then turn it off drain the engine and manifolds and install it in the boat, A minute or so run time will tell you that info without screwing up your cam break in later.

Then when you can back it into the pond on your property, take care of the cam break in process with all your instruments hooked up normally

I would connect to the intake hose either with a fake lake or TimmyT for the water supply, other option remove the clamp from the bottom of the boat and pull off the intake hose and slide the garden hose inside the intake hose for supply, all of these methods work fine although I do not like the fake lakes.   

 No need for a bucket, the bucket is used to verify your Raw Water Pump actually works.  In this case that is not necessary so the garden hose water supply should be all you need.

In my case I fire it up with the water supply on full open, once things are sorted out and the exhaust is putting a lot of water on my driveway I start reducing the water supply while watching my gauges and watching the exhaust.   No need to spin 3,000 RPM, I would shoot for 2,000 and not more than 2,400 RPM.  You can crank your idle screw up to hold the RPM constant if your throttle will not hold the RPM constant.

MOST important, use an oil that does have a higher amount of the ZDDP.  Most Diesel oils are good for this and the custom Oils also work well.   Standard automotive oils will help your cam fail.

Verify your engine is ready to start, do not start cranking the starter before you are ready to fire the engine.  Check your timing to make sure it is close enough for an instant start.  Double check all spark plug wires to make sure the boat is wired correctly.  A common problem is to wire the dist cap the wrong rotation, clockwise vs counterclockwise or cross two wires.  It has to be correct.  Make sure there is oil in the engine.  ( don't laugh many engines get wrecked due to people getting excited and forgetting the new engine does not have oil in it)   Pre Prime the Carburetor or if it is injected cycle the key from off to On, hold 3 seconds and do this 3 or 4 times to prime the injection system. On a Carburetor system put about two teaspoons full of gasoline directly into the carburetor right before turning the key to start.  Put the spark arrestor back on.   Turn on the cold water supply full blast and Start the engine.   

If it starts right away and it should fire within 5 seconds of cranking since it is pre primed the first thing you do is watch oil pressure.   You should get oil pressure right away, maybe 5 seconds from start.  If you do not get oil pressure kill the engine and find out why.

Once started, you have good oil pressure run it up to 2,000 RPM right away.  So within 30 seconds of start, you verify oil pressure and have it revved up to 2,000 RPM and keep it there.  Listen to the engine, there should be no knocks or tapping.  A lifter or two may clack for the first 30-60 seconds but then should be quiet and smooth.  If the lifters keep clacking something is wrong so shut down.  (usually an oil gallery plug missing)

Next while checking for oil and water leaks you can give it a timing adjustment, not for perfect tune but to make sure you are close to the factory setting.   At 2,000 RPM you should have around 20* timing.  That may not be perfect but it is close enough for a very safe cam break in.  

Now check your exhaust manifolds.  They should be cool to warm to your touch on the risors telling you the water supply is working.

Watch the oil pressure and temperature.   Do not let it get hot.  Heat on a new engine can be fatal.  It is handy to have an IR gun around, you can check temp at all 8 exhaust ports by the head, not by the risor where it is water cooled.  Even exhaust temps tell you the engine is working well on all 8 cylinders.  I might see 30-40* variation in exhaust temps but they are close normally.  On the Chevy the center has 2 exhaust ports so the left and right centers should Temp the same but will be different from the end ports which are single.

With everything checking out and the engine not getting hot you might be able to reduce the amount of water flow into the engine, just keep watching to make sure the temp does not go up in the engine.  If your hose does not supply enough water borrow a neighbors hose and use both hoses.  All this water has to drain somewhere, if you are in Cold country you might be creating an ice skating ring for the neighborhood so plan ahead.

Doing it this way I have not damaged the raw water pump impeller at all, it has constant water flow for lubrication.

At the end of the 30 minute break in bring the engine down to a normal idle, 700 RPM maybe, check your timing at this point.  Timing at idle will be somewhere around 10* but much more important is to check where that timing will be at 3,000 to 3,600 RPM.   Should be 34-36* and stay at that point as you rev to 4,000 or 4,500.  This is Total timing.   This gives you best power and economy when running hard.  Timing at idle is not nearly as important as your Total number.  With Timing set you can tighten it up and check it once more as it can change as you tighten the distributor down.  

If you have to shut down for any reason, start the 20 minute break in all over again when you are ready, don't go thinking you have 5 minutes done so you only need 15 minutes more.  Start over.  You are training those brand new Lifters to Spin every time they hit the cam lobe.  If one lifer does not spin it will take out a cam lobe in the first couple hours of use so give it the best chance to succeed and you are golden.  You have one chance to do this right.

Be careful, have an extra person on hand to help manage the water and check for leaks, help check temps, watch oil pressure etc.

I am timid having seen cam failures and heard many horror stories.   I have yet to have a cam go flat on me so I assume this process is good enough.   Best of luck and while it is making noise at 2,000 RPM and you are bored waiting for the last 5 minutes to pass take a short video for us to enjoy!

When I spoke to owners that had flat cam lobes, the common story was,  " I could not get it to fire up"  usually bad timing, trouble getting a gas feed flowing etc.   The engine has to fire up quickly.   Cranking and cranking on the starter is enough to cause lifter failure on start up.  

 Sorry if you know all of this already, my hope is at least part of this is new and can maybe avoid a cam failure.

Mark

The amount of water available to cool the engine seems to me to be the same in either method...however it enters the engine. Either the hose supply is enough, or it isn't...