New Prop-engine sync off?

O

OffLeash

New member
Hi all ...help, I need some consensus

I just went from 3 blade stainless steel props to Solas aluminum 4 blade props on my Verado 150's on a Tomcat.
They do seem to let me plane a at lower speeds but when I turn the "auto Sync" on, I find one engine is running about 30-40 rpm's lower than the other. They used to run about the same with the 3 blade props.

Could it be that the new pops are not tuned and would this cause the difference in sync?
Any other Idea's?

Thank for any thoughts
Mike
 
I have never had a boat with "auto sync"--but it should be only by RPM. off the engine computer. "New" props are not always exactly on pitch and balance, and I have had several props scanned and tweaked to get them in balance and the same pitch. The boats ran smoother then.

Is one engine counter rotating? If so which side is it on? The aluminum props have more "flex" than a SS prop does. I have always run 4 blade SS props on my cats.

Early attempts of t engine sync depended on vibration. Then there was a device hooked to the coil, and the lights became steady if both were firing at the same time. But I believe all modern ones are straight off tachometer output.

I have always synched outboards by vibration--and sometimes the techs were off a few RPM. Certainly a difference in pitch or balance would make a difference in perceived vibrations. I wonder if your techs were just a little off before, and you didn't notice it??
 
FWIW- I have auto-sync with my two Honda 150's and some days they stay within 5 or 10 RPM and yet on other days they seem to keep chasing each other as the RPM keeps increasing. I'm not sure if it's the sea state conditions, the trim on the motors, boat weight distribution, or the side I got of the bed, but it usually improves the next time I take it out. Go figure?
 
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