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Tachometer adjustments

M

maxtor

Contributing Member
"Just curious if a tach can be

"Just curious if a tach can be adjusted or if it's off a bit, simply needs to be replaced? I've got a 120HP Mercruiser and the tach on this boat is off. When the boat is shut off, the tach sits at about 600 RPM. Recently had it in the shop, and the guy told me that in the low end, it's pretty close, but in the high end, the tach is off. (reads higher than what it actually is). Is this something that can be adjusted?? Or should I just go buy a new tach??

Thanks"
 
"The needle may be at 600 when

"The needle may be at 600 when the engine is stopped, but does the needle drop to zero with the key on and the engine stopped?

There may be an adjustment on the back of the gage to adjust the bias high/low."
 
"As above but check with a sec

"As above but check with a second tach so you are sure the one in the shop is correct. Reason is, if the one you have is correct and you lower the reading and re-prop to make the rpm higher you could be turning the engine to fast."
 
"Okay, thanks. I'll check

"Okay, thanks. I'll check it out.

Doing a lot of reading here, I see the mention of PerTronix. Switching from points to electronic ignition using their conversion kits. Is this a wise investment or is this just a matter of preference? So, just switching to the PerTronix Ignitor would do the trick??
I assume that getting the timing checked after this is installed would be a good idea.."
 
seperate conversation from the

seperate conversation from the tach?

Yes. A good investment and not expense. Makes things maintanence free and reliable. Pleanty of this stuff around for cars. Not sure if it makes a difference. Mallory ignition makes good stuff as does MSD. Timing would need to be set as part of the install.
 
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