Temp sending unit
Thread Starter
Racer
Joined: Jan 2004
Posts: 398
Likes: 0
From: Eastern Shore Maryland
Temp sending unit
I have a set of early 80s era heads and the temp sending unit thread size is smaller than the original 71 sb heads size. So thinking I could just use a 80s era temp sender away I went. WRONG it just barely registers 120 degrees. So my questions is has any one cracked the code on which smaller thread temp sender works w/71 guages?
Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,501
From: Little Rock AR
They are nothing more than a variable resistor. You can tune them with a rheostat and then find a resistor with the same ohm resistance for a cleaner solution. This is close but there would still be some error as you move away from the setpoint but that would be difficult to quantify or observe.
Alternately, you can machine the cylinder head for the new sender thread. I have done this a few times and it is a lot easier than it sounds. Just work carefully or take it to a pro. Just another way to git 'er done.
-Mark.
Alternately, you can machine the cylinder head for the new sender thread. I have done this a few times and it is a lot easier than it sounds. Just work carefully or take it to a pro. Just another way to git 'er done.
-Mark.
Thread Starter
Racer
Joined: Jan 2004
Posts: 398
Likes: 0
From: Eastern Shore Maryland
I'm heading to the parts store, I remember when I worked at one there was a area in the back of the BW select book that outlined temp sensor specs by resistance, so wish me luck. I was hoping someone just did this yesterday and had a part number written on their hand.HA HA
Last edited by qwik-tripp; Jan 5, 2007 at 10:10 AM. Reason: spelling
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I have done this just recently, I forgot to machine for the stock large 1/2 npt sender unit, so found a Ford truck 5.0 sending unit from like '89 works fine mechanically, change the connector to plug over it....
BUT, I had to get into the gauge to make it line up ok.....take that white flat ~50 ohm resistor off the back of the gauge...i'ts mounted from the center tab/ground to another post on the meter directly across from it....
substitute a 15 ohm resistor ...any 1/2 watt will do....just tuck it under the nuts, and secure normally.....Then take a 470 ohm 1/2 watt resistor from the gauge green wire across the flat connector to the pink positive side....
gauge should be damn near dead nutz on....good from 120f to about 230f, under 120 who cares?? above 230f the alarms should go off anyway....
BUT, I had to get into the gauge to make it line up ok.....take that white flat ~50 ohm resistor off the back of the gauge...i'ts mounted from the center tab/ground to another post on the meter directly across from it....
substitute a 15 ohm resistor ...any 1/2 watt will do....just tuck it under the nuts, and secure normally.....Then take a 470 ohm 1/2 watt resistor from the gauge green wire across the flat connector to the pink positive side....
gauge should be damn near dead nutz on....good from 120f to about 230f, under 120 who cares?? above 230f the alarms should go off anyway....
