Ford 4000 alternator

Hi there. My granddad recently got his old Ford 4000 repaired after the head gasket blew. He had the guy repairing it put in some new gauges(none of the old ones worked). The guy took out the original gauge panel, and put in an ugly piece of black plastic with only an oil pressure and engine temp gauge.

I'm intending to put the original gauge panel back in after making some modifications to it.

Anyway, my question is about the tachometer. The guy who worked on the tractor replaced the generator (which also didn't work) with an alternator, one made for a Chevy truck, I think.

Since the tractor doesn't have enough RPMs for the alt., he put a smaller pulley on it. Does anyone know if I can install a tach drive on this particular alt., and whether or not the RPM reading will be accurate, with the smaller pulley (which I think makes the alt. spin faster than the engine)

The alternator is a "Delco Remy BG" stamped with the numbers 21201118, and bearing a sticker with 7127SW3 on it. It is a single wire, and starts charging once the tractor is revved up one good time (it doesn't stop until the tractor is off, according to the "mechanic"). It has a built in charge regulator, which keeps it from overcharging the battery.

The tractor is a 68 model Ford 4000, 4 cylinder.

And one other thing, I don't necessarily need an rpm log (the thing that looks like the mileage recorder in a car, or something like this: [000243420}).

What I want is a needle gauge that'll tell me my current RPM's.

I also want to know if the different sized pulley (different from what was on the generator), and by consequence, the alternator's differing speed from that of the engine, will have any effect on the accuracy of an RPM gauge (tachometer).

Any help is greatly appreciated, thanks in advance

S.B.Hahn

Ford didn't build a 4 cylinder 4000 in 1968- it was a 3 cylinder but from your other descriptions you definitely have a 3 cylinder, post 1965 4000.
Yes, the tractor originally came with a Lucas generator that drove the tachometer through a cable attached to the rear of it. The mechanic replaced it with a common GM 10si alternator that can be bought rebuilt for about $45. Changing the pulley on the front of the alternator will change it's speed causing an alternator driven tach to read incorrectly. You can buy a kit that includes the proper tach driving alternator to convert from the generator to an alternator. You can also buy a replacement instrument panel with new gauges for that tractor.

(quoted from post at 10:22:20 02/02/13) Ford didn't build a 4 cylinder 4000 in 1968- it was a 3 cylinder but from your other descriptions you definitely have a 3 cylinder, post 1965 4000.
Yes, the tractor originally came with a Lucas generator that drove the tachometer through a cable attached to the rear of it. The mechanic replaced it with a common GM 10si alternator that can be bought rebuilt for about $45. Changing the pulley on the front of the alternator will change it's speed causing an alternator driven tach to read incorrectly. You can buy a kit that includes the proper tach driving alternator to convert from the generator to an alternator. You can also buy a replacement instrument panel with new gauges for that tractor.

Click to expand...

........and the reason the mech didn't install an alternator WITH the mechanical tachometer drive on it, is that it would have cost about ten times more!

If it's a 68 it's a 3 cylinder engine or it's not a 4000...

As far as the alt goes... if you're going to run a tach off the alt you need to have the correct size pulley which is 1/2 the size of the crank pulley. That said... if you want to drive a tach off the alt you need either a Delco 10DN with a drive or a Delco 10si it from Tisco that has been adapted with a drive. A standard Delco WILL NOT have a drive as the rotor shaft is not bored to provide a drive. Also beware that not all 10DN were set up to adapt a drive. Some were for AG applications but a standard truck application will not be... You also need an external reg for the 10DN wheras the 10si is internally regulated.

Another option... IF the tractor has a post '72 engine block the oil pump drive arpeture is adapted to accept a tach drive... so you'd just install a new oil pump shaft with the appropriate bore for the drive, add the drive in place of the welch plug in the hole... then install an x600 series instrument cluster from the years 76 to 79 and everything should work.

Rod

The Tisco kit was in the 350-400 range. A good quality, lifetime reman 10si is over 100 without a core.

Rod

so.. what ya got.. a pre 65 4 cyl 4000?

post 65 3 cyl 4000

or post 65 4 cyl 5000 with 4000 decal on it?

sounds like a post 65 machine to me so far with the genny driving the tach.

I didn"t realize the number of cylinders was such a big deal when asking about electrical parts. But come to think of it, I think it is a 3 cylinder. My grandad told me it was a 4 the other day, but he probably wasn"t thinking. The old ford hasn"t run in a while, we only just now got it running after a year of sitting behind the barn; his newer Mahindra,big red toaster looking thing, is a 4.

Thanks for all the info, I think I know what I need to.