checking rpms without tach

so i was reading my manual in the governor adjustment section, and it outlines a way to check the rpms without a tach.....but it seems dangerous to me. basic process it says is jack one of the rear wheels up off the ground, put a mark on it, run the tractor in 1st gear and count how many times the mark goes around. gives a little table in there to convert to engine rpms. 10 times=400 engine rpms, 12.5 times=500 engine rpms and so on....question is, has anyone tried this? does it work? like i said, it seems dangerous to me, like the tractor could take off , but what do i know? ha what do you all think?
 
You can buy a handheld tach pretty cheap. You just wrap the wire from the tach around a spark plug wire. Works good for me.
 

i have one of those, but have not been able to get it to work, the numbers jump around all crazy. i wrapped it around a spark plug wire, but it doesnt seem like its working.
 
(quoted from post at 12:00:35 03/15/19) has anyone tried this? does it work?

I tried it, briefly. I assume it works in the sense that it allows you to calculate the RPM, as long as the manual did the math correctly which I assume they did.

But, like you, it seemed more risky than I liked. I only did it once. Maybe if I had a really solid way of jacking it up so that I knew it could not rattle loose no matter what happened...

I bought a little digital tach that I installed. Pretty cheap if I remember correctly. It has a sensor wire on the coil, and is powered off the battery. I like knowing the RPM while using the tractor. But then again, my TO30 is 12 volt now. If yours is still 6 that solution won't work. And it doesn't look "original" at all.

You can calculate the engine RPM off the PTO shaft (with the right formula, it's in one of the manuals I have) if you have/buy a handheld unit that will measure the PTO RPM.
 
(quoted from post at 10:55:19 03/15/19)
(quoted from post at 12:00:35 03/15/19) has anyone tried this? does it work?

I tried it, briefly. I assume it works in the sense that it allows you to calculate the RPM, as long as the manual did the math correctly which I assume they did.

But, like you, it seemed more risky than I liked. I only did it once. Maybe if I had a really solid way of jacking it up so that I knew it could not rattle loose no matter what happened...

I bought a little digital tach that I installed. Pretty cheap if I remember correctly. It has a sensor wire on the coil, and is powered off the battery. I like knowing the RPM while using the tractor. But then again, my TO30 is 12 volt now. If yours is still 6 that solution won't work. And it doesn't look "original" at all.

You can calculate the engine RPM off the PTO shaft (with the right formula, it's in one of the manuals I have) if you have/buy a handheld unit that will measure the PTO RPM.

so you wrapped it around the coil wire and not a spark plug wire? i have a tiny tach that only has 1 wire (used it to tune my chainsaw once upon a time before i tuned my ear) and i tried that around a plug wire and it didnt give me a reading really, numbers just kept jumping around. ill try it on the coil wire and see what happens. my tractor is a 12 volt, curious what tach did you put on there? dont really care if its original looking as this is a working tractor, and function serves over fashion. thanks!

-danny
 
I would feel safer just making an educated guess on the RPM than trying that!

The tractor would need to be very securely blocked up and up against an immovable object. Remember you will be standing in front of the wheel when adjusting the governor. Any sudden change in speed could very easily bounce it off the stand. If I were going to try it, I would remove the wheel.

Or get one of these hand held tachs. A very handy meter, especially if it still has points. It will let you check the point dwell under real running conditions.
Tach Dwell Meter
 
cool, im glad im not the only one freaked out by doing this, and its the recommended way to do it without a tach! went ahead and ordered one of those wireless laser tachs and ill get it off of the pto, doesnt have to be exact, just a rough ball park. thanks guys!
 
I have read, Ferguson Owners Manual for the TO-30? You should get 540 rpm at the PTO when the engine is at 1500 rpm .
 
Here's another option, handy tool to have around. The rubber point lets you check rpm on any shaft where you can get to the center; while the wheel lets you check surface feet per minute on any pulley or flywheel (which can be converted to rpm if you know the diameter).
https://www.amazon.com/DT6235B-Digital-Contact-Tachometer-Surface/dp/B00GRQHW0M

I've run cars with the rear wheels in the air, don't see why a tractor would be any worse. Yes, it's risky, but then, so is operating a tractor normally.
 

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