As you might remember, I put an Indigo prop on the boat this season, trying to get my RPMs up. The prop appears to be working well - quiet, smooth, pushing me along nicely. My tach reads around 1400-1500 RPMs at a cruising speed of 5.3-5.5 kts.
My direct drive A 4 matched with this prop should not do this. Tom, at Indigo, sent me an email after he read my post here suggesting that either he was way off with the pitch or my tach is way off. But a T27 with his prop should not go 5 and change knots at 1500 RPMs. Perhaps the gauge is not set for 4 cylinders.
Its an ISSPRO I bought from MMI. The instructions that came with it note an access port where pins can be adjusted for 4 6 or 8 cylinders. My tach, however, does not have this. There is a small port which appears to give access to an adjustment for the needle, to zero her out. There is nothing else.The large hole is for the light. I attached a couple of pics. Maybe one of you has some experience with this. I'm be off to Harbor Freight tomorrow to pick up a diagnostic tach.
By the way, the gauge is two years old and has rusted on the trim like crazy. Disappointing for a marine gauge.
Any thoughts on what I have, what I should do?
Thanks
Chris