superbenk
Commander
- Joined
- Oct 27, 2008
- Messages
- 2,033
I put an electronic points conversion kit on my boat today! VERY happy with the difference already even just in the driveway!
Anyhow, I took the opportunity to fiddle with my tach as well. I confirmed on my last outing with my shop tach that the dash tach is reading a bit high as the RPMs increase so I wanted to fiddle with the calibration. I've read on here about setting the tach to 4, 6 or 8 to match the number of cylinders however on my tach I had the numbers 1, 2, 3, 4 & the arrow was pointing to 2 initially. I turned the screw all the way to 1 & back up to 4 before bringing it back to 2. Then I adjusted it down & the RPMs on the tach reduced a lot so I brought it back up to just above 2 and got it to match my shop tach. I'll see how it matches the engine now on my next trip. It continued to match the shop tach up to 2k RPM (highest I wanted to go in the driveway) so I'm hopeful it's set.
Two questions I had:
1. What do the 1-4 numbers represent? Is there any logical meaning to them or are they just graduations on the scale? How should I read them so it's not just trial & error to calibrate the tach in the future?
2. When I was laying under the dash with the engine running, I could hear a weird squawking noise from the back of the tach. It almost sounded like something was spinning on a shaft with runout and vibrating or something. Is that a sign of a crusty old tach ready to give up the ghost (it is 32+ yrs old)?
Forgot to add my boat details, it's a 1980 Century 190 w/ an OMC 140 engine & Stringer 400 drive (as per my sig).
Anyhow, I took the opportunity to fiddle with my tach as well. I confirmed on my last outing with my shop tach that the dash tach is reading a bit high as the RPMs increase so I wanted to fiddle with the calibration. I've read on here about setting the tach to 4, 6 or 8 to match the number of cylinders however on my tach I had the numbers 1, 2, 3, 4 & the arrow was pointing to 2 initially. I turned the screw all the way to 1 & back up to 4 before bringing it back to 2. Then I adjusted it down & the RPMs on the tach reduced a lot so I brought it back up to just above 2 and got it to match my shop tach. I'll see how it matches the engine now on my next trip. It continued to match the shop tach up to 2k RPM (highest I wanted to go in the driveway) so I'm hopeful it's set.
Two questions I had:
1. What do the 1-4 numbers represent? Is there any logical meaning to them or are they just graduations on the scale? How should I read them so it's not just trial & error to calibrate the tach in the future?
2. When I was laying under the dash with the engine running, I could hear a weird squawking noise from the back of the tach. It almost sounded like something was spinning on a shaft with runout and vibrating or something. Is that a sign of a crusty old tach ready to give up the ghost (it is 32+ yrs old)?
Forgot to add my boat details, it's a 1980 Century 190 w/ an OMC 140 engine & Stringer 400 drive (as per my sig).
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