2000 mercruiser 350 mpi modifications

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bannister

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Re: 2000 mercruiser 350 mpi modifications

GPS is set to measure speed in knots. Fuel consuption is measured by a digital fuel flow meter.

Next weekend I will look at base timing, exhaust flappers, clean the injectors, run diagnostics, check spark plug gap, and distributor cap.
Then take her for a quick cruise around and will inform you of the findings and results.
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Is it possible that the exhaust flappers are stuck open and partially block the exhaust?
Just remembered that they had signs of overheating (plastic had something like bubbles on it) but at the time I thought it might be normal.
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Is it possible to change them with the boat in the water?
 
Bondo

Bondo

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Re: 2000 mercruiser 350 mpi modifications

bannister said:
Is it possible to change them with the boat in the water?
Click to expand...

Ayuh,... If the water runs in,...

Yer boat is Waaaaay to stern Heavy....

If the motor has the standard risers, 'n not added riser blocks, ya should be Ok, in the water...
 
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TilliamWe

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Re: 2000 mercruiser 350 mpi modifications

But if the shutters have fallen off their pins, they are at the bottom of the Y-Pipe, and that requires removal of the outdrive to get them out. Obviouslt that can't be done in the water. So remove your exhaust elbows at the top of the y-pipe and see what's there.
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Just came back from the boat.
Shutters are in place and working.

I used a timing light to check timing....

On the engine cam cover there is the mark with the vee notch on it.
On the harmonic balancer there is a long groove on the metal that when set to service mode it aligns with the notch on the cover.
Next to that long groove there is a white paint mark (clockwise).

My question is which one of the markings on the balancer is supposed to align with the notch on the cover when the engine is set to service mode?
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Anyone?

Am I correct to believe that the groove on the balancer is marking TDC so my timing is set to 0 ?
 
Don S

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Re: 2000 mercruiser 350 mpi modifications

The notch in the timing cover and the groove in the dampner = 0?, TDC
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Thank you all for your replies and support.

Borrowed an advance timing light from a friend and advanced the timing by 8 degrees.
The white paint mark on the dampner was indeed the 8 degrees mark.
All that time I was struggling with 0 degrees timing !!! and not even my mechanic (certified) didn't bother to take a look.
All he said to me was "you need a 6.2 mpi".

After setting the timing the idle became smoother. So ropes off and go test it.

3 people on board, 80 gallons of fuel, full water, props full of barnacles and a light chop.

The boat came right up on plane without tabs, and reached 5000 !!! trimmed up. (think I will order a set of 4 blades now.....)
Then I backed on the throttle and kept it at 3600 rpm cruising at 25 knots and the fuel consuption was 5 liters per hour lower than before!!!
Did not take a reading of speed at 5000 rpm because I only kept it there for a few seconds as the chop was getting bigger and a toolbox opened speading the tools on the deck. But who cares...........
I can not believe how much difference it made.

Thank you all again.
 
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HT32BSX115

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Re: 2000 mercruiser 350 mpi modifications

Glad you found the problem!!

Timing can make a HUGE difference! just make sure that you're setting the timing IAW(in accordance with) the Mercury service manual!


Regards,

Rick
B3.gif
 
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TilliamWe

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Re: 2000 mercruiser 350 mpi modifications

I knew there was something wrong with it. Good job finding it.
You don't need the B3 propset with a 4 blade front prop, you need a 24p "high thrust" set. Or a "cupped" 22p set. Both are available from Mercruiser, of course. But 24p will be "plentiful" on EBAY.
 
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HT32BSX115

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Re: 2000 mercruiser 350 mpi modifications

3600 rpm cruising at 25 knots
Click to expand...
(28.8mph) with a 2.20:1 drive is still giving you 15% slip.

That might seem high, but you have a pretty heavy boat. You might be able to reduce it a little at different speeds and playing with the trim......... Your lowest slip will probably coincide (approx) with your highest planing MPG.


If it turns 5000 or is up against the REV limiter (5100?) you might consider the 24p Props.

I see them all the time on ebay too......they're the cheapest ones.....

I am running 26p props, 1.81:1 and get about 10% slip at 4600 RPM (57mph) but my 21ft boat is MUCH lighter.
 
Tail_Gunner

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Re: 2000 mercruiser 350 mpi modifications

Nice call TW and i agree with the 24 if you can call duo's 24p i played around with slip and your fathers boat numbers. But i dont believe cupping will help much with that much mass er hull...Just good old fashioned big eared pusher blades
 
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TilliamWe

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Re: 2000 mercruiser 350 mpi modifications

I only mentioned the "cupped" props that Mercruiser introduced a few years back as sort of a "bridge" between his current 22s and a set of 24s. In case for some reason the 24s dropped the WOT rpms too far, then the cupped 22s should be "in between" the 22s and the 24s.
 
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bannister

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Re: 2000 mercruiser 350 mpi modifications

Not actually,
Almost same cost as the Mercruiser ones.

I am thinking same pitch, more blades would do it for me.

Or not?
 
Don S

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Re: 2000 mercruiser 350 mpi modifications

Now that you have the engine running right, you should start a new thread over in the Prop forum. Not many will notice a prop question in a thread titled 2000 mercruiser 350 mpi modifications
 
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