Proofmeter rotation

[CTPhil]

I have 3 Ford 3 cylinder diesel tractors, 2 1978 models, 1 1975. I'm going to be needing a new proofmeter assy. on a couple of them. The 2 1978's have a dial that runs counter clockwise, and as near as I can tell the 1975 is clockwise. Externally all engines look identical.

The parts book is confusing as to what the rotation should be on the 1975. (420) It has a nearly disintegrated proofmeter which looks like it ran CW, but no tach cable or adaptor at the oil pump shaft. What am I missing? Is there something internal that would cause the oil pump shaft to run the opposite way on the 420, or did the tachometer cable originally get driven from another location on the tractor?

Thanks in advance!

 

[HakanTh]

I am not familiar with the 420 model, however the 1000-series (1965-1975) had an arrangement where the tachometer (CW) was driven by the generator. The cable was attached to an angle drive at the back end of generator. Perhaps your tractor was originally equipped with the same arrangement and later on a generator to alternator (without tachometer drive) switch was made, and as a result there is nowhere you can connect the cable.

 

[CTPhil]

Thanks for the reply. I believe that all 420's had alternators however.

 

[CTPhil]

Shameless bump. RickB?

 

[RickB]

Take a look at the coolant temp sender on the 420 and see if it is 1/8NPT or 1/4NPT.

 

[CTPhil]

It looks like it's 1/4". It also looks like it hasn't had a tang on it or wire near it in a very long time.

 

[CTPhil]

I'm not fully confident that I'm getting accurate readings from my current instrument cluster...

 

[RickB]

There is a specific proofmeter listed for most 3 cyl Fords '75 - '79 or something in that range. That one, or an aftermarket one (if offered) matching that part number would be the only one to fit and match both your tach drive and sending units. If you wanted to swap out the senders, the later, more common proofmeter would do as well. I haven't run the numbers to see which would be cheaper.

 

[CTPhil]

I'm still wondering what determines whether the rotation is CW or CCW on seemingly identical engines...

 

[banjodunn]

G'day Phil they are referring to the direction of rotaton of the tacho needle itself, the one in your pic would be CW. There are several aftermarket units around, have a look at the bare co site lots of ford stuff there
Just reread your post it relies on whether your tacho is oil pump or gen driven as to the rotation

Jon