I have a 51 f3 ford with an 8BA flathead. I have one opening on the drivers side head that is for the temperature sending unit. On the passenger side I have two openings. What are the two openings for on the passenger side head? Is one for another temp sending unit and the other the heater control valve?

When I bought this a few years back the openings had nothing in them but I know one is for the temp sending unit.

Thanks.

 

you are correct, heater control valve (or heater hose if your control valve is on the firewall) and other sending unit. that's the way my '47 car is.

 

This is the setup

 

I spent a considerable amount of time chasing an overheating problem in my panel truck until I realized I had a bad sending unit. A minute or so after I started my truck the dash temp gauge would peg out to past "H". I decided to install mechanical gauges, one on each side and the engine never registered over 180°. I build a dual gauge bracket and have my gauges mounted just to the right, under my ignition switch.

I know this really doesn't have much to do with your question but I thought I'd just throw it in here. I like being able to see the temperature of both sides of the engine and I trust the mechanical type system more than the no so great stock system.

 

Thanks for the diagram. What is the excessive heat unit and where can I find one or is it the same as temp. sending unit used on the right side. I'm looking in the LMC catalog and they have water temp. sending unit but no excessive heat unit.

 

When you say other sending unit is that the same as the temp sending unit on the driver side head?

 

The sending units are different. The right unit has one screw terminal which is connected to the first terminal on the left sending unit and the from the second terminal on the left unit the wire goes to the dash gauge.


Double terminal unit left side part# 8A-10990

Single terminal unit right side part# 8A-10884

Both are listed on Mac's Auto Parts website for $50 each

 

EDIT: well darn it Bob, you're quick on thekeys this morning!

Look closely at the diagram. The excessive heat unit is a switch with two terminals, that opens the circuit. When there is no current in the circuit (or when the truck is turned off), the temp gauge reads full "H". Under normal conditions the right head's unit sends pulses to the gauge, sending it towards "C" in proportion to temperature. It is not like any modern temp sender, they are almost all resistive devices.

The excess heat unit is 8A-10990, the sender is 8A-10884. Dennis Carpenter has them, hold your breath: $55 each. LMC has a totally bogus listing and wants $90 for it, I'd stay away. I'd guess there are plenty of good used ones, either on eBay or you could check with Antique Auto Supply in Arlington TX, 817-275-2381

 

Thanks Ross and Bob for the information and part numbers. This helps a ton!

 

i used two totally independent units for more accurate readings. this way you can monitor each bank of cylinders, isolate what bank has a problem, and catch a problem before it becomes major. if left unit, (on original set-up), quits or pukes, you got nothing. just my 2-cents

 

The way I understand the original setup is the right unit varies in resistance causing a different amount of current flowing in the heater wire in the gauge. Higher temperature lower resistance in right unit, more current in gauge, higher reading. If the left side goes over some unknown temperature, it switches from just passing the variable current from the right side to grounding out causing zero resistance and max current through the gauge to very quickly heat up and move to hot reading.

 

Sort of... the right side unit ("Sender") is kind of like a flasher unit. Heat from the coolant and current causes the sender's contact to break, then it cools, then the contacts make again, over and over. If the engine is hotter, it takes less heating from the current to heat the bimetal enough to break the contact, and then it cools slower, so it stays open more -- and as explained before, with zero current, the gauge reads "H". It's a pulsing type of action that is damped in the gauge.

 

just curious, those of you that have two separate gauges, one for each head, how close to each other does the temp run?

 

59-ab two independent units--very close to each other. within 2 or 3 degrees.

 

same here bout 2-5 degrees difference . i have been running two factory gauges , relocated the fuel down to the bottom . my old furd has had a mechanical oil pressure gauge in it for a very long time i'm told by freind's of the po and i left it . took the oe oil gauge and put it up now i can't find it ........... i just ordered new gauges from mid fifty instead of pursuing the i wanna be different thing , and replaced the oil gauge with another temp . oh and they're the 12 volt units they sell .it'll be rewired and the oe brakes rebuilt for now as i can no longer bear to just look at it !!!!!!!!!!!! i'll get the other frame done then transfer the parts to it . so look out stu and tim the green snail will be terrorizing the streets again !!!!!!!!