Hi Guys - I'm nearing completion of my first engine build in about 30 years, and have run in to a bit of a snag. My new Dart Iron Eagle heads have a 3/8 inch hole for the temperature sending unit, and most of them require a 1/2 inch hole. Ordinarily I'd just relocate the sending unit on the intake manifold next to the thermostat, but I have an interferance issue there with the radiator hose using the stock thermostat housing.

Any suggestions on where I can find a temp sender for a 3/8 inch hole? I'm trying to keep the engine looking as stock as possible, so I'd like to locate the sending unit in the head if possible.

Thanks as always!!

Whatever you end up doing, make sure the sender has the same resistance figures and temperature coefficient as the one made for your gauge. There are some variations out there that aren't interchangable. A cold resistance comparison would be a good first step - should be within 10% or so of the one you have. Does that make sense?

I was talking to Autometer about needing to calibrate a sending unit and they said as long as you use the same brand sender and gauge, that calibration is never needed. What type of gauge are you using? Have you tried to go to Home Depot, etc. and attempt to locate a reducer? They may have one that goes from 1/8" pipe to 3/8" pipe. My drivers side head uses 3/4" pipe and the passenger side uses 1/2" pipe. I don't understand that one. My intake uses 1/2" pipe as well.

A "straight" instead of angled stat housing will solve the interference issue:yes:

Luke,
What type of gauges ? If they are the original GM gauges, I am pretty sure there is a sender available that will work.

I think, Standard Parts #TS6 for large holes, #TS26 for smaller holes.

I am using a Billet Specialties 45* angled swilve type thermostat housing. It gives me plenty of clearance around my sending unit. I have my fan switch right at my thermostat housing.

Again, what gauge?
Autometer's come with a 3/8" sender, and a fitting to adapt to 1/2"
Info for the factgory guage is above.

If you're talking the sender for the idiot light, I lived this exact same problem here a few years back. Unfortunately, I forget what the guys here told me to buy, was from some sorta mid 80's buick. Hope someone puts a number up, cause mine's gone bad and I need to buy another!

for the stock gauge, get one for an 86-ish Chev pickup.
if it's an idiot light, ask for one for an 86-ish Caprice.
if it's an aftermarket deal, then head to your local NAPA store and get some brass adapters.

Here's their web site. I think they are all large 1/2" pipe up through early 80's.
I once did resistance testing of my 67 gage sender and compared it to my 84 pickup, which was completely different resistance.
David

http://www.smpcorp.com/web_app/catalog/publiccatalog.asp

The sensor should be installed by itself into the water flow. If the sensor is on an adapter, the gauge will read different because its sensing bulb is out of the flow.

That depends on how long that sender is. If it reaches past the adapter then it won't make a difference.

I would believe a trial & error test would need to be performed.

I've never had any luck with an adapter on a sensor/sending unit. Maybe its a singular case on my part.

Thanks for the input everyone. My car is an RS and currently is only equipped with idiot lights. The more I think about this, it's probably about time I put some guages in this thing...especially with a $6K motor about ready to go in it this winter.

How else would you get the sender into the head? Plus, if the adapter caused any kind of reading issue, why does Autometer send them with their temp gauges? As long as the sender comes in contact with the coolant, it will provide a reading. The coolant does not necessarily have to be flowing. All it has to do is contact the sender. I have never had a problem with my sender giving me any reading other than what the coolant actually was using an adapter.

How else would you get the sender into the head? Plus, if the adapter caused any kind of reading issue, why does Autometer send them with their temp gauges? ...

I don't think the problem is adapting a small sender to a larger hole with a bushing which is what Autometer provides - a reducer bushing. The problem is trying to put a larger sender in a small hole. You can stack various reducers to make it work, but you'll wind up with the problem Everett is describing.

for the idiot light, you just need a sensor for a car new enough to have the 3/8" hole, that had an idiot light.

While I'd never be without real gauges, idiot lights are good too. They holler LOOK AT ME real loud, get your attention when there is a problem, where you might not notice a gauge right away.

While I'd never be without real gauges, idiot lights are good too. They holler LOOK AT ME real loud, get your attention when there is a problem, where you might not notice a gauge right away.


That's assuming the light bulb ain't burned out!!:yes:

That's assuming the light bulb ain't burned out!!:yes:
lmao, don't assume, look. oil light should be on with key on engine not running, temp light turns on while cranking

Well, I bought a sending unit for an 86 Caprice with a warning light. Haven't tried to install it, but it looks like it'll fit fine.

I had the same problem with my car. I resolved the problem by cutting the 1/2 sending unit down on a lathe and rethreading it to 3/8. FYI Measure the resistance of the sending unit off the caprice against the one in your car before installing.

FYI Measure the resistance of the sending unit off the caprice against the one in your car before installing.
Don't bother. The idiot light is a simple switch. open normally, zero ohms to the case when it's hot enough to trigger. Note that those things trigger at very high temps, 250 or so. If it ever comes on, turn the heater on full blast and get the car moving. If it ain't off within a minute, shut her down.

Had to revive this thread, as i need your help. I have factory console gauges. I have vortec heads with the small hole. I bought a sensor that the parts guy thought might work. Well it does work, but is way too sensitive. It pegs cold while driving & almost pegs right before the electric fans kick on. Did you guys ever find out if the 86-87 truck gauge works? Thanks, Scott

Did you try the one Everett suggested?

"I think, Standard Parts #TS6 for large holes, #TS26 for smaller holes."

I have one from a 70 Camaro but I do beleive it is slightly off calibration.

TTFN
Mat

Here is a thread where a guy says he turned the sender down and threaded it.
http://www.camaros.net/forums/showthread.php?t=1496