Loneranger
Well-Known Member
- May 2, 2008
- 1,068
- Boat Info
- 2000 SeaRay Sundancer 270
- Engines
- 7.4l Mercruiser w/ Bravo III
I know at least with procedures such as timing that you need a more accurate tach measurement than the dashboard tach. How inaccurate are dashboard tach? Do they tend to over or under report RPM's?
When I bought the 270 with Bravo 3 it had matched 24 pitch SS props on it. I damaged the prop on a log so I bought a set of 22 pitch which is what the sea ray website states should be on this boat. I never actually monitored the RPM at WOT for the 24 pitch but with the new 22 pitch at wide open throttle I was getting 4200 rpm and 38 mph which is at the lower end of the recommended WOT RPM range according to Mercruiser. I was just wondering if I this data is good enough or do I need to measure a more accurate RPM.
I now have the 24 pitch set refurbished so I may put them on one day to try it again but my understanding is that increasing pitch by 2 will decrease the RPM by maybe 400 which would be well below the recommended WOT RPM.
Thanks for any input.
John
When I bought the 270 with Bravo 3 it had matched 24 pitch SS props on it. I damaged the prop on a log so I bought a set of 22 pitch which is what the sea ray website states should be on this boat. I never actually monitored the RPM at WOT for the 24 pitch but with the new 22 pitch at wide open throttle I was getting 4200 rpm and 38 mph which is at the lower end of the recommended WOT RPM range according to Mercruiser. I was just wondering if I this data is good enough or do I need to measure a more accurate RPM.
I now have the 24 pitch set refurbished so I may put them on one day to try it again but my understanding is that increasing pitch by 2 will decrease the RPM by maybe 400 which would be well below the recommended WOT RPM.
Thanks for any input.
John