Date: Mon, 03 Jan 2000 00:20:44 -0600 From: Bob Lyle Organization: Lyle Professional Services Newsgroups: alt.autos.studebaker While looking for some info on SW tachometers, I came across this info on gas guages and sending units. I thought it might be of interest to someone, so here it is. If you want more, it came from the FAQ section at: www.stewartwarner.com How do I select the correct fuel sender? Stewart Warner makes a variety of adjustable fuel tank senders for a multitude of applications. Fuel senders have to match the resistance range (measured in ohms) of the gauge. The following are examples of the resistance ranges of gauges and senders: Stewart Warner Full 29-33 ohms Empty 244-250 ohms General Motors Full 0-2 ohms Empty 91-93 ohms Ford/Chrysler Full 0-2 ohms Empty 70-73 ohms All Stewart Warner fuel senders meet the SAE standard for five bolt flange pattern. Stewart Warner does not make a direct replacement fuel sender for an automotive OEM application. If you're not sure of the fuel tank's impedance, determine its' resistance by following this method: Disconnect the fuel tank sender from the gauge. Connect an ohmmeter across the fuel tank sender. The meters positive lead on the fuel tank sender's output and the ground lead connects to the fuel tank sender's flange. Manipulate the position of the float arm with a piece of wire or some other device so that you can position the float arm in the full and empty locations. The Stewart Warner fuel tank sender will measure 240 ohms at the empty position and 33 ohms at full. GMAC fuel tank sender will read in the opposite direction. At empty, it will read zero ohms and at full it will read 90 ohms. Ford/Chrysler fuel tank sender will read zero ohms at empty and 73 ohms at full. Stewart Warner offers several adjustable fuel tank senders so tha t you can select the correct unit to fit your particular application. For Shallow Tanks: 385B-F Adjustable 6" - 12" Depth 385C-F Adjustable 6" - 12" Depth 385B-F is L.H. which means left hand arm for tanks where most of the tank's capacity is on the left side of the sender's flange when mounted. 385C-F is R.H. which means right hand arm for the opposite situation. For Deeper Tanks: 391A-F L. H. Arm 10" - 15" Depth 391B-F R. H. Arm 10" - 15" Depth 391C-D L. H. Arm 15" - 24" Depth 391D-D R. H. Arm 15" - 24" Depth 5.Can I mix Stewart Warner gauges with competitor's senders or visa versa? Pressure Systems Both gauge and sender should have the same impedance to be a perfect match. For best overall performance, we recommend that you use SW gauges and senders together. Other manufacturers will specify that their gauges work with SW senders. We don't sanction the mixing and matching but in some cases, their gauges will match our pressure senders. A 240 ohm gauge should be matched with a 240 ohm sender. Fuel Level system Fuel systems are quite the same as pressure systems. Gauge and fuel sender must have the same impedance to function correctly and both should be at the same ground potential. For best performance, SW suggest that you purchase our matching gauge and sender combination. -- Big Boblyle@worldnet.att.net Austin, Tx (512) 272-5445 '78 Avanti II (Baby #2) '52 Studebaker 2R5 1/2ton C-Cab ("Angel") '55 Studebaker 2 dr Sedan '66 Studebaker Daytona Sport '62 Studebaker T-Cab parts truck