370B max RPMs

[Richard Sosdorf]

Just splashed the boat for the season and on the first run I checked WOT rpms and came up short on the starboard motor. It only reached 2985 on digital tach. I just had the props tuned to the same specs from previous years. Previous results were 3085 on starboard and 3100 on port. The Port hit 3070+. Also the bottom was stripped and completely redone in the off-season so I was hoping for even better numbers than I got.

I did notice the starboard motor was idling low at 540 rpms compared to the port at about 610-620. Is there any corrolation to low idle rpms and not reaching Max rpms? Any ideas what I should be looking for to explain the low WOT rpms.

Topic

[Bill Desmarais]

Richard Sosdorf wrote:

Bill thanks for the response. I’m still trying to figure out what going on with the loss of RPM’s.

Tony ?
Whadda ya think ??

[Richard Sosdorf]

Bill thanks for the response. I’m still trying to figure out what going on with the loss of RPM’s.

[Bill Desmarais]

Hi Mike ! that's my former 31 Blackfin I repowered

Hey there Mike. Thanks for the email. I didn’t realize this thread was my former Blackfin.

Tony,

Mike, bought my former 31 Blackfin. The one “you (from 3,000 miles away) , me and my mechanic” repowered back in 2009 with a pr. of your Seaboard Marine ReCon 370s, new ZF220A gears, SMX pumps, Double Double fuel filtration, SeaFirst steering ram, Envirovent.

You also custom fabbed the exhausts for the repower. You shipped them in May 2009…went MIA in the UPS system for 3 weeks……launched July 5th 2009, you were on the phone when I fired them off for the 1st time.

Pic is circa summer 2009. Seaboard Marine 370.

Cables were new @ repower 2009 and are the green CableCraft cables. Suppose to be a very good cable.
http://www.rosesmarine.com/products_enginecontrols.htm

I also remember that both engines were very close no load WOT with the Aetna tachs. 3275 + maybe..can’t be positive.

Has to be something simple…unless a prop is off some from what the final scan paperwork says.

The pic…memories….2008 ReCon 6BTA 370s CPL2008 “tricked out” the “Seaboard Way”.

Next to last pic is after I serviced the after coolers after season three. Plenty of Rectorseal # 5

The factory coolers were greased by Tony’s staff before shipping. Grease is the key !

No fuel cooler ! Not needed !!! Keep it simple.

“Where are the rpms” ?

[Richard Sosdorf]

Thanks Tony. I pulled the cable and pushed by hand and it goes to 3062. I just don’t understand how I can lose 100 over layup.

The spring moved pretty easily when I pushed by hand. I will lubricate it as you mentioned.

Is adjusting the throttle stop something I should mess with?

Rich

[Tony Athens]

No load spec for you engine is 3275 to 3325.. Sure you are hard into the throttle stop??– Your have an over spring–lube it well, remove the cable as test by hand so you see/feel how it works both at the high and at idle– They get rusted over over time.

As to messing with the stop screw–search U-tube for that..

Tony

[Richard Sosdorf]

I have atne digital rpm gauges so I believe they are acurate.

Just tested the no load WOT and here’s the results
Port 3354
Starboard 3257

So I’m approximately 100 short on starboard. How do I fiquire out what do next. Is there an adjustment on the throttle at the injector? Have Something to do with the throttle cable or even something in the controls at the helm?

Also is there any coralation with the low idle rpms and not hitting the max

[Stephen Oliver]

Oh and dont do what I did – spent a whole day checking and stripping everything due to control levers that were not aligned and chasing one engine appearing to rev far higher than the other at WOT – only to have Tony suggest checking the accuracy of the tacho with a laser tach – and I was upto 300rpm out.

If your idle appears low you could be out on RPM reading at the higher range too… easy and quick to check as it may just be that simple.. fingers crossed for you as all I had to do was adjust the tacho via a small pot on the rear of the gauge

Steve

[Richard Sosdorf]

Jeff,
Thanks for the response. I’m going to the boat tomorrow to check the no load WOT. How did figure out the that you where not getting full travel on the throttle? Is there a bolt adjustment or did you push it full by hand. How did you correct it. Rich.

[jeff]

Are you able to get full RPM in neutral? (at the dock, warmed up). I was down on RPM and chased it for a while until I found I wasn’t getting full travel on throttle. Doh!

JD, out….

[Richard Sosdorf]

The props were just tuned and installed. They were measured before and after tuning and they are the same as the previus tunings. I was present when the props were installed by the marine and they did not block the prop. They use a wrench on the shafts.

Any idea were to look next.

[Rob Schepis]

Not uncommon for props to lose some pitch over time, did they do a before scan and an after scan? How about the cup, a small change in cup and where along the blade it starts/stops can also alter the effective pitch and hence change the rpms.

Who installed the props? If a prop is not properly chocked and is tightened with a big wrench a blade could have been tweaked. Chocking the blade at the radius could/will twist the blade..

[Author]

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