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Kooky idea??? Using a distributor to trigger a tach signal...
by
Jetmugg
on 29 May, 2013 07:55
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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.
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#1
by
vanbcguy
on 29 May, 2013 08:03
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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.
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#2
by
vanbcguy
on 29 May, 2013 08:06
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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.
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#3
by
RabbitJockey
on 29 May, 2013 09:26
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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
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#4
by
Gizmoman
on 29 May, 2013 09:57
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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
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#5
by
CRSMP5
on 29 May, 2013 11:52
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jett... they made factory non vac pump parts, oil pump, gear and cap...
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#6
by
RabbitJockey
on 29 May, 2013 11:54
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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
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#7
by
theman53
on 29 May, 2013 13:56
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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?
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#8
by
Gizmoman
on 29 May, 2013 14:33
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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.
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#9
by
R.O.R-2.0
on 29 May, 2013 16:26
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#10
by
tyb525
on 30 May, 2013 15:34
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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.
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#11
by
Gizmoman
on 30 May, 2013 16:02
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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.
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#12
by
tyb525
on 30 May, 2013 16:18
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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...
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#13
by
vanbcguy
on 30 May, 2013 18:34
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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.
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#14
by
92EcoDiesel Jetta
on 31 May, 2013 04:58
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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?