QuicheLorraine

For those who have them, what sensor did you use that works with the stock gauge? My new AFR195's have too small a hole in the side for either the plug that came out of the right head, nor the coolant temp sensor that came outta the left head.

windup

The one from an 82 crossfire fits I think.

Gordonm

Yes this is a big problem with newer heads. I know there are a lot of guys working on this and trying to come up with a solution. I did find a sensor working with my parts guy a number of years ago. Unfortunatly I did not write down what it was for or any numbers. It is very close on the temp readings. Not perfect but good enough. I know this does not help but there are people working on this. Some have tried to turn down the big sensor to the correct thread size.

QuicheLorraine

Can't turn down the big one - the bulb doesn't even fit the hole, let alone the threads!

And it kills me too because the temp gauge was perfectly accurate before.

7t2vette

I may have the easiest solution of all: I drilled mine out and tapped them for 1/2" NPT to be able to use the stock sensor.

Gordonm

Look at these sensors. The fat one iwould say would not fit but that is not for your year car. The one with the thinner "bulb" should be the one and that one should be able to be turned down.

http://www.zip-corvette.com/Zip/dept.asp?dept_id=2222

JimT

You can purchase a short 3/8" nipple, and a 3/8" X 1/2" adapter (all NPT pipe fittings from Home Depot). Insert the adapter and nipple into the head, then insert 1/2" sensor into the adapter. Works rather well.

74ZZ430

I had the same problem on my 74 when I replaced the heads. The bulb on the sensor was to large to get a 3/8" die over. I purchased a new stock sensor from Lectric Limited which had a much smaller bulb and had the new sensor turned down, works perfect..

C3 Stroker

You can have the hole machined out to accept the stock sensor, or do as I did.....locate the sensor to the intake manifold; it fits perfectly and is just as accurate there.

FYI, Readers ....If you order your heads from AFR, they told me the will drill the correct size hole for your sensor; just be sure to mention it when you order. Ken

0Willcox Corvette

Just two days ago I was working on this for 77 Sleeper.

What I’m doing is turning his original sending unit down in my lathe and then threading it to 3/8 npt.

For those with a lathe, this can be done in about ½ hours time and you would be ready to go. There is enough material in the threaded area to allow the old threads to be taken off and new threads cut. If you do this you have to be real careful, the jaws of your chuck can severally mar the hex head of the sending unit. I like to gorilla things so on my first there are pretty good marks on it. This test unit was the thumb nail sending unit and not the spaded one. . . But it is for sale too. . . You can order this one by calling sales if anyone wants it. I’ll let it go for the standard price of the sender I used.

Now for the time eating part of this post! ! ! . . . we have it turned down and ready to go but we are also going to match calibrate to his temperature gauge (dash unit) to the ohms output of the sending unit. This should produce a very accurate dash reading when completed. It takes me over an hour to do this but it is well worth it.

I can’t get this done for Sleeper until this weekend, tomorrow I’m subbing at the office for Tommy who has the day off so about the only thing I can do tomorrow would be take a picture of the smaller sending unit. (I polished the top of Sleepers, it looks like gold now).

Willcox Inc.

QuicheLorraine

Well I have verified over & over again, that my temp sensor was accurate using radar guns at radiator shops & repair places. Amazing as it is, my '76 dash gauge is accurate from 180* to 210* within a very small degree of error.

If you were to turn the sensor down & make it 3/8NPT thread, there would be no reason to test it - it's already accurate but doesn't fit the hole.

Vette79C3

As Ken mentioned you could have had them drill the correct size hole prior to shipment. I also forgot this prior to shipment. I went through three different sensors until I found one that was spot on with my gauge. Keep in mind that your sensor is in tune with your gauge. I couldn't use an adapter because my headers were in the way. Relocating it on top of the intake is an option but to me looked silly and out of place. Personal Preference. If your not having any luck I could locate the part number for you.

QuicheLorraine

Thanks for that. Right now there's another stumbling block keeping me from firing the motor: See my thread about the bad (possibly) guide plate in the head. Need to get that corrected before any other things get installed.

carriljc

I have mine located on the intake manifold and it is nowhere near accurate.
I have a separate sensor that goes to the ECM and my gauge reads about ~40°F colder(from memory & gauge markings aren't exactly clear) than the computer ECM...both are on the Intake manifold. The ECM reads where I would expect with my 180°F thermostat.
I'm going to have to try the adapter thing ...

QuicheLorraine

Yesterday I bought a 3/8 NPT nipple & a reducer. Two problems: First, the big sensor won't thread all the way down into the reducer. Secondly the arrangement would have hit the header.

jbowles49

I tried this nipple and reducer setup many years ago for a similar problem and it was not far enough into the water flow to be accurate. Glad you resolved the guide plate issue with Motorhead. It looks acceptable to me too based on your pics and efforts at finetuning. Good luck

gkull

Put your stock sensor in the intake manifold next to the goose neck.

Or you can buy the Volvo sensor that fits AFR heads that has the same ohm rating as the Vette sensor from Pep boys

No machining or dicking around!

carriljc

I'm ready to try this. anybody know the particulars?

rcread

I dropped my head off at NAPA, had them drill and tap the hole, and picked it up in the afternoon. $25 later, it was a perfect fit.