Diesel Engine tach calibration

gplume · Post by **gplume** » Sep 24th, '07, 21:00

Anyone have any methjods to share for calibrating tachs on a diesel. I am told i need to use a strobe light. No hits on google that make sense. Thinking about using an old timing light I have and scrounging around work for a pulse generator. Anyone know of somthing reasonable you can buy for the purpose of diesel engine speed calibration?

(This message means that I am finally operational after 2 years on the hard, and about 6 weeks in the slip working capped off by a smoked borg warner tranny that I had to rebuild as icing on the cake.)

In Memory of Vicroy · Post by **In Memory of Vicroy** » Sep 24th, '07, 21:24

Giff - tachs on a diesel that are not driven by a speedo cable are all electric....either off the alternator or a magnetic pickup. Either way they count pulses...you have to set the DIP switches on the back of the tach to the application...for example, a 6B Cummins has 159 teeth on the flywheel and you have to set the magnetic pickup tach to that...what engine and tach are you running?

UV

Bruce · Post by **Bruce** » Sep 25th, '07, 07:18

I think what they are talking about is a reflective tape hand held tach.

Maybe some of the guys that have one could either lend it to you to check or give a link to a supplier. There's a bunch.

Here's an example:
http://www.handtach.com/

I get mine from the guy that comes around in those nice tool trucks and tend to be more money.

If the tach is off, some tachs have adjustments on the back in the way of dip switches as UV said or an adjustable pot or nothing.

The flywheel pickup is the most accurate.
Altenator ac tap is the least accurate.

Rawleigh · Post by **Rawleigh** » Sep 25th, '07, 07:48

There is a cheap source for them that someone posted here not long ago. I bought one for less than $60, but I can't remember the name.

gplume · Post by **gplume** » Sep 27th, '07, 06:27

Guys - Thanks for your replies.

UV- Have Cummins V-504's. Originally, I assumed I had the type of pick up you mentioned, and ended up buying the wrong tachs. (Anyone want to buy some new Faria magnetic pick up tacks Cheaspeake style 0-4000 RPM?) I found out that my set up needs a tach desgined for an alternator pick up, but uses a sender mounted on the fuel pump/PTO unit. At this point, I am fishing for the right settings, because I am not 100% sure what the speed relation is between the pump and the engine. At the std settings, the RPMs don't seem to line up with the seat of the pants feeling, hence my desire to calibrate to a known std.

Bruce - Exactly what I was looking for. Many thanks for the link. Now I need to try to find one a little cheaper as hopefully this is a one shot deal. Still may take an old timing light and a sig genrator from work. Pretty sure I can make that work somehow. Have not figured out yet, what level of pulse I need to trigger my light...(still figuring and thinking, haven't experimented yet.)

Rawleigh - If you find that $60.00 source...I am all ears, becasue that is about what I would like to spend.

Bruce · Post by **Bruce** » Sep 27th, '07, 06:42

try this link, half way down the page on the left. 49.95

http://www.bosstoolsupply.com/index.asp ... =48&Page=1

gplume · Post by **gplume** » Sep 28th, '07, 06:06

Bruce -

Thanks greatly. Exactly what I was looking for. Just placed my order. Looks like there are a few more toys to add to my tool box as well.

Giff

bertram31.com

Diesel Engine tach calibration

Diesel Engine tach calibration

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