Olds64

Something just dawned on me. How do you put a tachometer on an Olds diesel engine? There is no ignition to hook it up to...

Was a tachometer ever available in the Oldsmobile B bodies with diesel engines in the late 70s and early 80s?

70 cutlass s

Most newer diesel engines use a signal from the altenator they have a post for it. You have to use a tach for a diesel.

Another type of diesel tach uses a magnet pickup.

Then the link shows an interface for diesel without a altenator with the W post. Then you can use a regular tach with it.

http://www.dakotadigital.com/index.c...rod/prd128.htm

Olds64

Cool! Thanks for the info Andy. I was just curious. It sort of hit me like a ton of bricks this morning.

joe_padavano

There are a few options. You can use a mechanical tach - there are actually small tachs that you hold against the balancer that measure RPM directly. There are vibration tachs that measure each cylinder pulse. As for the factory, there was a special Kent Moore tool called a Tach-N-Time or something like that. The tool had a probe that fit into the cylinder on the plastic timing tab. A small magnet in the balancer was picked up by this probe for measuring RPM and also to time the injector pump.

Olds64

Thanks for the additional info Joe. I bet that tool is impossible to find now. You would have to scour Evil-bay for it.

joe_padavano

Actually, one shows up on ebay about once every couple of months or so.

citcapp

The tach in my motorhome runs off the alternator. Found that out when the tach started jumping around and I traced it down to a worn fan belt. Changed the belt tightened it to spec and the tach worked fine.

Blk71SX

http://www.autometer.com/cat_gaugede...id=2602&sid=12

compedgemarine

on my 6V92 Detroit the tach is off a signal generator that is run off the end of one of the cams. they use the same type signal generator to run the electric speedometer.

greenslade

older diesel trucks [80-90 ]ran the tach off a pick-up on the flywheel.that was before electronics came along.