Tachometer question

Skeetbum

Cadet
Joined
Feb 21, 2007
Messages
24
Hi everyone, and thanks in advance for your time. I have a 1988 Bumble Bee bass boat that runs great and I'm just trying to work thru some minor issues with a couple of my gauges. My tach is made by medallion company and I'm not sure that it's giving proper readings. The motor is a v-6 Mariner 150, not a magnum but the smaller of the motors(I'm told) and I can regularly turn 6500 rpm's with a laser 2, 14", 25pitch prop with a cupped face. Not having been around these before my experience is limited but growing all the time. On the back of the tach the indicator goes 1 thru 4 and is currently set on 1, wondering if that is where it should be with my motor. Also wondering if the motor is actually capable of turning this prop that high. The speed is from mid to high 50's with me alone and a moderate load in the boat.
The other question is about the trim guage, which has never worked since I bought the boat in '09. I need some instruction on how to test the guage and sending unit to see where I am with this. Looking forward to your responses, and thanks again for your time.
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,204
Re: Tachometer question

The tach should be on 2, and your engine isn't turning 6500 currently. Max on that motor is around 5500. Also, is that speed on a gps or the speedo? In dash pressure based speedo's aren't worth much.
 

Skeetbum

Cadet
Joined
Feb 21, 2007
Messages
24
Re: Tachometer question

Thanks for the quick response. Speed is gps, I learned about the others early on. I'll put the indicator on 2 next chance I get. Also glad to know I wont toast the motor with over rev. It's a lot of fun to get there quick and trimmed up. Any ideas on the trim guage?
 
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