Tach on a diesel??

[Beck]

I'm getting my plans made for my diesel 62' Chevy stepside. I want a tach. Do most diesels with tachs have cable drive? What can I do to run a standard aftermarket tach? I was thinking of installing a hall effect pickup on the crank pulley. I doubt that would be enough current or voltage for the tach to work. I guess I could get out the old electronics book and try to make an amplifier for it, but how much current and voltage does it take? I get some really stupid ideas!

Beck

[enjenjo]

I have seen diesels with a tach that operates from a hall effects pickup on the ring gear of the flywheel. the notches are already there, you just have to mount the pickup.

If the engine has provisions for a mechanical tach, you could install a VSS on that, and use it to trigger a tach.

62 Chevy trucks could be had with a factory tach on the larger models, the dash insert will fit a pickup. The original tach was a SUN with the signal generator on the fender.

[Beck]

I have seen diesels with a tach that operates from a hall effects pickup on the ring gear of the flywheel. the notches are already there, you just have to mount the pickup.

If the engine has provisions for a mechanical tach, you could install a VSS on that, and use it to trigger a tach.

62 Chevy trucks could be had with a factory tach on the larger models, the dash insert will fit a pickup. The original tach was a SUN with the signal generator on the fender.

This engine/transmission is a Cummins 4bt with a 400 turbo so there will be a flexplate for the torque converter, not a flywheel.

I don' know what VSS is an acronym for.

What sent the signal to the signal generator on the original 62 installation. I like the idea of using a factory dash. I thought I would have to go to all aftermarket gauges if I wanted to put a tach in.

What ohm sending unit would be in the 62 dash cluster. I have a 0-90 ohm sender (standard, later model, GM) in the tank. Wasn't that something different in the early 60s?

[moparrodder]

Do you have  a cummins company shop anywhere close?  They should be able to get you what you need as far as a  tac hookup.  As far as the VSS this is just a shot in the dark, variable speed sensor.  Good luck getting it together, sounds like a decent power unit.


  Bill

[enjenjo]

A VSS is a vehicle speed sensor, there are some that have a connector to screw on to a speedo cable. It's a hall effects pickup.

On a 62 chevy truck, diesel engines used a mechanical tach, gas engines used an electric. The points triggered the amplifier.

Flex plate or flywheel, either one will work as long as it has a ring gear to trigger the hall effects pickup.

A BT Cummins should have a port on the bell housing for a pickup, it's used for diagnosis.  It may have a mechanical tach drive port on the PT pump too.

The fuel sender is 0 to 30 Ohms on a 62. you can adapt a later gauge, just find one that fits in the hole. Classic Instruments makes a universal 0 to 30 Ohms sender.

I just remembered, there used to be a tach that was triggered by harmonic vibrations, the sender just bolted to the engine block or head. Very reliable, but as IIRC they were about three times the price of regular mechanical tachs, so was not popular on trucks. No idea who made it, or if it's still available.

Ever factory tach dash for a 62 that I have seen, also had an air gauge, so they would all be from air brake equipped trucks.