Calibrating a tachometer

[495v]

I believe my tach needs to be re-calibrated. Can I do this myself? What is needed and how do I go about it. Thanks for any assistance.

 

[Trent]

Re: Calibrating a tachometer

Why, What's it doing????

 

[petryshyn]

Re: Calibrating a tachometer

easiest way is to compare its readings to a:<br /><br />>known accurate tach<br />>mechanical tach held on the end of crank<br />>strobe tach

 

[495v]

Re: Calibrating a tachometer

A buddy was telling me of this device that hooks to the plug wire to gauge RPM's. Is this a strobe tech? The reason I believe my tech is off because my RPM's are reading lower than they should. I contacted Ranger and they assured me I have the right prop. One dealer recommend a tuneup, compression check, and a few other things. My local mechanic said he couldn't see there being anything wrong with the engine, it runs to nice and smooth. He suggested a check the back of the tech to make sure it's on 8 cylinder, and possibly calibrate it if it's off.

 

[jegervais]

Re: Calibrating a tachometer

495-<br /><br /> IF you have a Merc tach, you may be able to calibrate it. The newer ones have an adjustment screw on the back side. You'll need to hook up an accurate shop tach (inductive pick up will work) to the engine. Compare readings at the middle of your rpm range and adjust as required. For example, most outboards run up close to 6000 rpm, the tachs are calibrated at 3000 rpm. As you know, I'm not a MerCruiser guy, so I imagine you'll want to calibrate that thing around 2500 rpm.<br /><br />-John

 

[495v]

Re: Calibrating a tachometer

How ya been John? It is a Mertc tach. Would it be worthwhile to buy a strobe tech or something similar, or should I have the shop do it.

 

[jegervais]

Re: Calibrating a tachometer

Been ok, busy as all get out, but ok. It's up to you, but how much use would you have for the tach afterwards?? Maybe borrow one from a generous neighbor??<br /><br />-John

 

[495v]

Re: Calibrating a tachometer

Unfortunately, all of my neighbors are carpenter's. How much would one of these gadgets cost? I'll compare a cost to that of what my mechanic would charge and go from there. The problem right now is the bust season. If I did it through the shop I would probably have to wait until end of July or so and I would rather get this thing on the money sooner. Out of curiousity, do you think it's possible that the tech is right and there is a problem somewhere in the engine? The engine runs so smooth that I can't see there being a problem but what do I know. I do know it's not the prop.