Alternator question 1080 Massy Ferguson

[Torchmf]

1080 Massy Ferguson 1970 year 318 Diesel engine. Bought tractor and the previous owner replaced the alternator with one with out track drive. Went back to the original so the tack works again like it should. Have the right alt on but it seem like the tack is showing faster than it is really going. The hour meter is moving but not sure of what rpm to run at to see if it is accurate. I would think at PTO speed.

Hear is my question! What is the correct diameter pulley?
2 question at what RPM does the alternator start charging?

 

[murphy1244]

Welcome from Ohio, should start to charge at 600 rpm

 

[The kid]

Welcome to TractorByNet. What diameter was the old one vs new one? What came original on the tractor. Genny or alternator?

To verify your tachdrive vs engine rotation, you will need a digital laser tachometer. I've seen them for a low as $35 on ebay. Model airplane pilots will use these to tune their engines. Search Digital Laser Photo Tachometer. Or not worry about it and use the RPM that works best for you. I replaced my old Genny and tachdrive with an alternator w/tachdrive. Not really worried if the RPM's don't match exactly. I will use the RPM that works the best. Are you sure the tach runs off the alternator and not somewhere on the block?. -kid

 

[Torchmf]

Thanks guys for the response so far. The tractor cam with alternator just dont know what diameter the pully should be. If I cant get any clear answers on this. I will look into the Digital Laser Photo Tachometer. Thanks

 

[The kid]

Here's one on eBay cheap.
Digital Laser Photo Tachometer

I may get one of these for the toolbox -kid