Finally I get to post my - "Is my engine running right w/ correct prop thread"

Finally I get to post my - "Is my engine running right w/ correct prop thread"

So here is the story.

I own a
`99 Monterey 180M
4.3L Volvo 4.3GL PWTC 190HP
SX-M Outdrive P/N 3868893 1.79X
Solas 14.5"x19" Amita
I run it at 5000+' feet

Purchased this boat last fall. First boat since being in my 20's (20 years ago and they were old boats even then). Made 2 trips out on the water and then put the boat away for the winter w/ end of season maint. I have had it out 4 times this year with a bunch of upgrades and maint between then and now.

I has 330 Hours indicated on the hour meter w/ an engine change at about 300 hours due
to the previous owner delaying the winterizing a little to long and cracking the block.

Since purchase I have:
Changed the oil (Merc 20w50)
Changed the outdrive oil (Volvo synthetic 75w-90)
Changed the plugs, cap, rotor.
Changed the propshaft output seal (it was leaking).
Greased the U-joints (they looked and felt great with no rust at all).
Checked engine alignment (smooth as silk at 0-90-180-270 degrees)
Compression tested, all cyl 165+/-5PSI (which seems good due to my operating altitude)
Greased the transom bearing (felt as smooth as glass).
Changed U-joint bellows.
Changed exhaust bellows (and found the exhaust flapper valves in the lower unit).
Replaced the impeller pump.
Replaced the somewhat rough MW 14.5"x19" prop with a Solas Amita 14.5"x19".
Installed a keel-guard.
Replaced the Series 24M battery with a 27M battery (the old one was 5 years old).
Replaced the thermostat (old one was shattered and would never let the engine get above the minimum line on the temp gauge)
Polished and waxed the entire hull (it had a fair amount of oxidation).

So here is the question.
This past weekend I finally had the combination of boat in good enough shape, small enough waves,
wife in a good enough mood to ...... LET ME MAX IT OUT!

This was done on fairly smooth water at 9AM, 70Deg F ambient, engine warmed up to 125F, 2 adults and 2 teens (+ gear) + gear, full tank of gas (20 gal).

Do these numbers make sense?

Here are the results at WOT.

4200 RPM indicated (this is a calculated 50ish RPM low based on testing it in the driveway against my digital tach at 2k RPM engine speed....I don't want to rev it to high on muffs)
Trim 50% up
40.2 MPH (Measured with GPS)
Trim 75% up
42 MPH
Trim 100% up (Started to get a little porpoising)
42.5 MPH

Lower throttle settings.

3500 RPM indicated (again a little low to reality)
Trim 0% (full down)
30.3 MPH (GPS)

3000 RPM
Trim 0% (full down)
23MPH (GPS)

Overall I think I am satisfied with the performance (which I guess is all that counts)
but I have noticed a few things.

1. I have gotten some pings (1 or 2) from the engine if I go from idle (in gear) to WOT really fast.
2. This engine combination runs really cool. It seems to have trouble maintaining 150F even with
a new thermostat (admittedly water temp is only 60-65 degrees right now).
3. The RPM at 20MPH-ish seems a little high.

Could this combination benefit from a different prop? Not wiling to go SS but might try a different
diameter/pitch. Main use is blasting from one swimming/fishing cove to another and pulling tubes/skis/wakeboards
and other toys with my kids on them. My main lake is 7 miles long and 1/2 mile wide so long distance cruising isn't going
to happen.

Does this system sound like it is running OK overall?

Thanks,

Dave

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

4200 RPM indicated

Click to expand...

Ayuh,.... I'd try a 17" prop,....

1. I have gotten some pings (1 or 2) from the engine if I go from idle (in gear) to WOT really fast.

Click to expand...

That's Detonation, from too big a prop, or bad gas,....

Probably the prop,...

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

At 5000 ft you're down about 15% on power.If its a carbed motor its running rich.
At those numbers your slip appears really low about 5%.
I do wonder if the tach may be higher than thought. If I use 4700 rpm slip is a more typical 11%.
as rpm goes down slip will go up so at 4200 you would probably expect slip somewhat higher than 11%
At 4700 11% is a reasonable number.
Perhaps a test with your other tach before a prop change.
How was your hole shot?

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Answers to some of the questions/ideas posted:

1. Gas is brand new. I have run through multiple tanks worth this season already.....purchsed
from a gas station that has boats lined up to fill every weekend......they sell a lot of fuel.
However the boat calls for 92 Octane (at sea level) and based on Don S advice and my
background of carbed engines at 5000+ feet you can run 89 Octane fine.


2. I wonder if the timing is a little advanced. Last owner ran this boat mostly at 8000+ feet but
he isn't around to ask if he advanced it more for altitude......and no I haven't checked it because there are
only so many hours in the day.

2. Carb idle jet leaned out for altitude....used lean drop method to check it and it ended up very VERY close to where it was set before.
Previous owner stated he had it leaned out while he owned it (Boat was originally from CA).

3. Tach could be off more than I think. My digital tach is optical and relies on a white mark on the main pulley and fairly close
proximity to the pulley to operate so not really doable on the water, at least I am not crazy enough to try it while the boat is
bouncing over the water. I have a multimeter with a inductive pickup....just haven't had a chance to try it yet on the water.

4. However it doesn't sound like an engine running at 4700RPM....I put myself through EE school working as a mechanic and my first
job after college was designing engine controls for diesel engines so I have spent many hours listening to engines at different RPMs....I think I can tell the difference between 4700 and 4200 but my tin ear and my butt dyno are not calibrated so I could be wrong.

5. I agree the slip numbers seem abnormally low at WOT.

6. Hole shot seems good i.e. It will pull my skiers out quickly and my wake boarding son over if I am not carefull. Punch it in gear and indicated RPM jumps straight to 3200 and pegs there until it starts to come up on plane then steadily rises as the boat speed comes up.

Thanks,

Dave

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Don't trust your calibrated ear drum. :joyous: Things tend to sound a little different at speed on the water.

I'd verify the accuracy of your tach, on the water and at speed before going any further. It isn't uncommon for them to be off. Mine registers about 150rpm too high at 5,000rpm, but dead on at 1,000.....has since it was new. Beg/borrow/steal a shop tach; digital is best but doesn't have to be.

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Re: Finally I get to post my - "Is my engine running right w/ correct prop thread"

Good hole shot and low wot rpm usually don't go together.