Kooky idea??? Using a distributor to trigger a tach signal...

[Jetmugg]

Yesterday, I had a "brain flash" that I would like to share, and take feedback.

I'm building a 1.5 VW diesel for a land speed record attempt.  I do not need or want a vacuum pump on this engine.  I'm thinking of putting a conventional gasser distributor in its place, and using the spark signal from the coil to trigger a tachometer.

Any thoughts on this idea?  It would use factory parts, requiring nothing to be welded to the crank pulley and would not need fabricated brackets to hold a magnetic sensor.

Why not?

Steve.

[vanbcguy]

I may be remembering wrong but I believe the helical gear on the diesels is cut in the opposite direction to the gassers as the IM shaft spins the opposite way, but the oil pump still turns the same way.

There is factory hardware out there to delete the vacuum pump, though it is not particularly common.  These diesels were used in some generator or marine applications where a vacuum pump wasn't needed.

[vanbcguy]

Further to that, one of the most elegant way of triggering a tach I've seen so far is using a sensor attached to the timing belt cover pointed at the cam or IP pulley, and then a couple of marks or magnets (depending on sensor type) attached to the pulley.

[RabbitJockey]

Yea the diesel intermediate shaft spins the opposite direction,  its probably easiest for you to use a dakota digital converter with the dodge cluster and a vw alternator with w terminal or an aftermarket diesel tach, although it is hard to find one that goes to 6k

[Gizmoman]

I know a lot of folks prefer analog tachs but I installed a "tiny-tach" which uses the pulse from one of the steel injector lines - flawless. No moving parts, and several other functions as well. I believe you can even set an alarm. I don't know the upper RPM limit offhand but I'm sure its well over 6,000

OK - here's a link http://tinytach.com/diesel.php

[CRSMP5]

jett... they made factory non vac pump parts, oil pump, gear and cap...

[RabbitJockey]

I know a lot of folks prefer analog tachs but I installed a "tiny-tach" which uses the pulse from one of the steel injector lines - flawless. No moving parts, and several other functions as well. I believe you can even set an alarm. I don't know the upper RPM limit offhand but I'm sure its well over 6,000

OK - here's a link http://tinytach.com/diesel.php

I think those things are sweet.  I like the ford magnetic pick up style kevin made too

[theman53]

I think you MIGHT be able to press the distributer gear off and press the vacuum gear onto it and run it just as you say. I don't know what you would have to run for power to it, or if it would just run off the pickup, or would the tach need to see spark?

[Gizmoman]

One nice feature of the Tiny Tach is it will record and save your highest RPM - something that may be of interest to you at the end of your run.

[R.O.R-2.0]

http://www.vwdiesel.net/forum/index.php?topic=30442.0

this works great with better tachs, doesnt work with a stock mk2 tach tho..

it drove my Autometer tach like it was nobody's business..

[tyb525]

I'm looking at buying a tiny-tach, I'd love to have an accurate RPM measurment for idle and road rpms. I don't need a fancy analog tach.

[Gizmoman]

Good choice - accurate to 1 RPM (I think) and saves you'r highest rev.
Too bad it's twice as much as the gasser version - still well worth it though.

[tyb525]

Yeah, trying to find a deal on one. I like fabbing things up, but I don't trust a sensor that close to the tbelt...you never know...

[vanbcguy]

If you mount something on the belt cover measuring off the cam, ip or im pulley it can be set up without necessarily needing to weld anything and can be mounted well clear of the belt.

[92EcoDiesel Jetta]

If you mount something on the belt cover measuring off the cam, ip or im pulley it can be set up without necessarily needing to weld anything and can be mounted well clear of the belt.

 What exactly are you measuring on those pulleys?