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914World.com _ 914World Garage _ Ignorant Gauge questions

Posted by: BMXerror Sep 21 2007, 06:40 PM

Hey all. I've got a '70 with practically no instrumentation. There's a tach, a speedo, and a "combo" gauge with a fuel gauge, gen. light (yellow?) and an oil pressure light (Green?). I'm trying to change this by adding CHT, Oil Temperature, and Oil Pressure gauges.
Stupid question here, but where do you tie the oil gauges into the system? Do I have to make up some fittings for the temp gauge, or is there an unused port somewhere on the engine?
Also, the dual pressure sender that I got from Pelican comes out into what looks like two oil fittings, not two electrical tabs.
Finally, would there be a problem with cutting the CHT wires to size? They won't squeeze through the loom with the connectors on, but as I understand it, the CHT gauge works differently than others (VDO cockpit CHT gauge). I can solder pretty damn well, but I don't want to be messing with something I don't understand.
Any help on any or all of these would be great.
Mark D.

Posted by: Dave_Darling Sep 21 2007, 09:23 PM

You want the temp sender down in the sump. Do a search on "taco plate" to see how the stock setup works. You can drill a hole in the non-sender "taco plate" to mount the sender in, but part of the sender sits out in the air and it won't read correctly.

The Pelican gauge needs to have its case grounded. Either mount it with a clamp around it onto a good ground, or fasten a wire to the case somehow. The two fittings you see are plastic nuts, you can twist the wires into a loop to hook around the posts or crimp a loop connector onto the end of 'em. Tighten the nuts to hold the wires or loops on.

Don't shorten the CHT wires; de-pin the connector. IIRC, it's a (relatively) standard Molex connector, and most electronics supply shops should have a pin release tool.

--DD

Posted by: marks914 Sep 22 2007, 07:58 AM

Sounds like you should have gotten one of these:
http://rides.webshots.com/photo/2261913870057582025ukSHaJ

Do not cut the CHT wires, the gauge will not work properly, believe me I have tried it!

Mark

Posted by: BMXerror Sep 22 2007, 01:49 PM

Anybody know how those CHT gauges work? Mine works with the battery unhooked. So I'm guessing it's not electrical.
Mark D.

Posted by: Dave_Darling Sep 22 2007, 02:11 PM

It's electrical, all right--but it generates its own power! The thermocouple generates a very very small amount of power which varies depending on the temperature differential across it, and the gauge reads that power and displays it as temperature.

--DD

Posted by: BMXerror Sep 22 2007, 07:15 PM

Okay, thanks Dave for all the info. It really helped. I've still got lots of work to finish by Oct. 8th.
Mark D.