Is there a trick to adding a set of aftermarket electric gauges, but still using the factory sending unit?
Do you have to match the sweep (0-80 psi) from the sender to the gauge?

Does this make sense?

 

The sending unit and gauge are a matched set. Are we talking stock replacement gauges or custom aftermarket?

 

I think the sending unit in the electric gauges is based on a resistance that varies with the applied pressure. So you would need a sending unit with the same resistance readings across the gauge's span.

 

I think this is it…
but they rarely list the output or input ohm rating for a gauge OR a sender.

oldscutlass…I’m talking about trying to match up a stock sending unit to an aftermarket gauge.

 

I added a set of aftermarket gauges to mine. I put a tee where the oil pressure sending unit was and used both the original sending unit for the dash light and had the tube go to the aftermarket gauge set.
i did this back in the 80's and it is still working.

 

Peter, the problem is both resistance range and direction (are high ohms hot or cold, for example). Heck, Stewart Warner gauges require different sending units for their own products depending on the range of the gauge. Unless you get incredibly lucky, this is a dead end.

 

It seems incredibly random and unthought out.
And then I came across THIS sending unit for a set of gauges that I liked.
I tried to find the schematic but could not...
What a mess!? No idea how this works.