Sending units in heads, question and help please
Thread Starter
Melting Slicks
Joined: May 2003
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From: Rochester Kent
Sending units in heads, question and help please
In my stock heads of my '81 there is a sensore/sending unit in each head near the header on both sides, I think one is the temperature sending unit but what is the other on the other side? Anyone help me? 
Race Director
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From: Scottsdale Arizona
Originally Posted by 78pacer
Do you have an electric. aux fan? If so, thats your sender.
Mike
Mike
Team Owner
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From: Ontario
Driver's front in cylinder head is for temp gauge (stock configuration). Intake has two thermal vacuum switches (TVSs) for EFE and EGR as well as one rear snout for transmission and headlight vacuum.
Last edited by Paul L; May 11, 2005 at 01:01 PM.
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From: Scottsdale Arizona
Thanks Paul. this looks a little different than what I have, which isn't to say that it is wrong. My thermostat housing has both tvs's attached and the hole for the second tvs in your picture; well I'm not sure what is there. that's where I thought that the sender was. I'll have to have a look.
Bottom line though Paul is that the sender should be on your passenger side head. An easy way to check if the switch isn't working is to pull off the lead and, with the ignition in the run position, ground it out to the manifold. If everything else is right, the auxilary fan should come on, as it should when running hot.
I always thought that I had a bad fuse or other issues since I did this with the sender on the other side and the fan would never come on , Doh
Bottom line though Paul is that the sender should be on your passenger side head. An easy way to check if the switch isn't working is to pull off the lead and, with the ignition in the run position, ground it out to the manifold. If everything else is right, the auxilary fan should come on, as it should when running hot.
I always thought that I had a bad fuse or other issues since I did this with the sender on the other side and the fan would never come on , Doh
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Thread Starter
Melting Slicks
Joined: May 2003
Posts: 2,253
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From: Rochester Kent
Thanks guys,
The reason I'm asking is because I went to install the sender units into my new alum. Edelbrock performer heads, but the holes in the heads are larger and the the sender units are too small. I can put the temp sending unit in the manifold near the thermostat but that then leaves me with the problem for the aux. fan sender unit. Any ideas, anyone else had this problem?
The reason I'm asking is because I went to install the sender units into my new alum. Edelbrock performer heads, but the holes in the heads are larger and the the sender units are too small. I can put the temp sending unit in the manifold near the thermostat but that then leaves me with the problem for the aux. fan sender unit. Any ideas, anyone else had this problem?
Thread Starter
Melting Slicks
Joined: May 2003
Posts: 2,253
Likes: 1
From: Rochester Kent
Originally Posted by paul67
Driver's front in cylinder head is for temp gauge (stock configuration). Intake has two thermal vacuum switches (TVSs) for EFE and EGR as well as one rear snout for transmission and headlight vacuum.
Race Director
Joined: Jul 2004
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From: Scottsdale Arizona
Paul,
What carb are you using? As I recall, the two VTS vacuum circuits control the vapour canister purge and the egr system. Asside from vacuum advance, I' cant think of any other hoses that you couldn't simply block off.
What carb are you using? As I recall, the two VTS vacuum circuits control the vapour canister purge and the egr system. Asside from vacuum advance, I' cant think of any other hoses that you couldn't simply block off.
Thread Starter
Melting Slicks
Joined: May 2003
Posts: 2,253
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From: Rochester Kent
Originally Posted by CA-Legal-Vette
Paul,
What carb are you using? As I recall, the two VTS vacuum circuits control the vapour canister purge and the egr system. Asside from vacuum advance, I' cant think of any other hoses that you couldn't simply block off.
What carb are you using? As I recall, the two VTS vacuum circuits control the vapour canister purge and the egr system. Asside from vacuum advance, I' cant think of any other hoses that you couldn't simply block off.
I am using an Edlebrock perfomer carb. I was thinking that the vacuum lines could just be blocked off aswell.
Also I am now thinking that the aux fan wont work now anyway because the computer has been disconnected, so the sending unit is not required. Do any other earlier years have aux. fans or was it just '81 onwards. I might just take out the aux. fan, any ideas?
Le Mans Master
Joined: Mar 2002
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From: Coming home from Luckenbach Texas
We got two threads going on here...
The aux fans started in '79. I had a similar problem to yours. Replace the temp sender (driver's side) with a unit from an '82 Corvette. On the pass. side, the sensor itself (it's pretty small) was threaded into a brass adapter. I made a new adaptor by drilling and tapping the correct size hole in a brass plug that fits in the new head.
The aux fans started in '79. I had a similar problem to yours. Replace the temp sender (driver's side) with a unit from an '82 Corvette. On the pass. side, the sensor itself (it's pretty small) was threaded into a brass adapter. I made a new adaptor by drilling and tapping the correct size hole in a brass plug that fits in the new head.
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From: Scottsdale Arizona
Originally Posted by Pauld
Also I am now thinking that the aux fan wont work now anyway because the computer has been disconnected, so the sending unit is not required.