Sierra 58255P Tach 7K Amega Review

The last tachometer was dead and then just went up to 4000rpm and dropped off as the engine revved up, this one works great. 1995 Mercruiser 7.4, uses 4p (4 pulse) 8c (8 cylinder) tuning for a four-stroke V-8 engine. The tachometer is powered by the gray wire that comes from the negative side of the coil to the transmit connector on the back of the gauge.

Installed in dock and worked fine. After about 2 hours, the actual use of the water block failed (the inside of the helmet never got wet or hot from the sun). Threw away the package so I have to eat $50. Foolishly expected more from Sierra. Update: I never bothered to remove the touch, but yesterday (months after the outage) it worked. Maybe you just need to shake things up? I soldered all my connections so I doubt it was the wiring but who knows. Improve rating to 3 stars.

It took me a while to figure out the correct settings for this, my engine (1981st 50hp 2-stroke Johnson ) was in not listed in the instructions. Turns out my motor uses a 5-pin setup. I ran a wire from the tachometer to the motor and connected it to one of the Stator 3 outputs. The reading seems reasonable and I have no doubt it can even be accurate within a few hundred rpm. You really need a way to measure engine RPM on the tachometer to know for sure. The tachometer looks great and is well…

Easy to install as instructions are included. Pretty close to the Mercury Verado I replaced, except for the "Q" at the bottom of the dial. I didn't get a chance to test it right away since the boat was in the garage for the winter, but I changed the engine oil and was able to get it working by putting it in a cut-down 55-gallon drum. I have the ability to see the engine parameters on my fish finder so I can compare the RPM reading on the new rev counter with the fish finder and they both show…