Ford 4000 automotive style tach

jwjsr

Member
I have no tach as I have the alternator without the tach drive option. I quote from another thread I was just perusing "One other option would be to add an automotive type tach that reads RPM's from the ignition system"
Is this doable on a 71 ford 3cyl diesel? Can I just go to the auto parts store and pickup any electric add-on tach?
 
I am not sure, but I believe you need to have a special alterantor that has a "tach " lead to make this work. Then you need to make sure the pulley is the correct size for the alternator to give the correct tach reading.

Bottom line, I take in many tractors that are goobered up and end up restoring them back to the generator and factory gauges.
 
Unfortunately, a diesel engine does not have an "ignition system" like a gasoline engine has. Those automotive type tachs read the electrical pulse for the sparking circuit and a diesel doesn't have spark plugs.

They do make electronic tach's that have a little magnet that you can glue to the flywheel and then mount the sensor close to the spot where the magnet passes by on each revolution and it senses the magnet as it goes by and uses that to count the rpm's. You might be able to mount the sensor on the timing access cover below the starter.
 
(quoted from post at 09:25:11 04/29/14) Unfortunately, a diesel engine does not have an "ignition system" like a gasoline engine has. Those automotive type tachs read the electrical pulse for the sparking circuit and a diesel doesn't have spark plugs.

They do make electronic tach's that have a little magnet that you can glue to the flywheel and then mount the sensor close to the spot where the magnet passes by on each revolution and it senses the magnet as it goes by and uses that to count the rpm's. You might be able to mount the sensor on the timing access cover below the starter.
Yes, I am familiar with that timing access cover as I was just trying to find the TDC mark on the flywheel, which by the way I never found as the manual doesn't specify or show which mark is TDC.
Is there a specific name for this kind of tach. Would I start with googling magnetic tach?
 
I just realized there's another problem with using one of those automotive tachs. They have a switch on them to allow them to be used on 4, 6, or 8 cylinder engines, but nothing for a 3-cylinder. So the best you could do (on a GAS 3-cylinder) would be to set it to 6 cylinders, and divide what it reads by 2.
For a diesel, your choices are going back to a genny, getting an alt. with a tach drive, or trying the type of tach Sean mentioned. OR... if your block is new enough (not sure when the change happened - is the plug below your oil filter a screw-in or drive in?), you could switch to the x600 style tach drive and tach. But that's probably the most spendy way to go.
 
They can also be run off the injection pump. 7000's came from the factory like that. BUT you need to have a model with an in-line injection pump. 4000's all have rotaries.
 
Yeah, I'm not quite in the restoration mode right now, it's not important enough to me to spend more than say $50. It would be nice to know the rpm I am turning my finishing mower.
 
I don't know if you're going to find one in your price range. All of the magnetic tach's that I can find are around $100.00 or more.
 
Now if this will work, I'll start my search for similar in $50 range
http://www.ebay.com/itm/Diesel-Engine-Tiny-Tach-Hour-Meter-Tachometer-Transducer-MDS-1Q-NEW-/331098302846?pt=LH_DefaultDomain_0&hash=item4d16ff297e
 
The Tiny-Tach brand makes thee different tach's and the pictures all look pretty much the same, so read the details to be sure of what you're getting.

The cheapest one, around $45.00, One gets an induction feed from the spark plug wire, so it only works on gas engines..

The second one, around $95-$100, uses a magnetic sensor with the flywheel, which is what I mentioned above.

The third one is specifically for diesel engine, and is also around $95-$100, and it somehow gets a signal from the pressure pulses in the injector lines, but I'm not sure how it senses that.
 
Sean, thanks or looking at those for me, I kinda like them, an hour meter is a nice bonus. If I can't find a used one quickly I might double my budget!
 

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