[Pepi]

Originally Posted by Formulabruce

Steve, so if you put it in the head, and your gauge reads correct, what is the actual engine temp at the T stat with an IR gun? does it match???

I would like to know also, thanks for all your work Steve, great documentation!!! :

[70FormulaRAIII]

Originally Posted by Transamric

In the 1970 PDM, sheet 480841 #2, the part is called a Transducer Assembly, #1513321, with option U30. The 9/1/70 Pontiac MPC has it as #1513321 also, but calls it a thermostatic gauge switch (round single conn.) (w/rally gauges or aux. gauges).

Here is part # 1513321 - according to the NOS A/C Delco box - threaded without the round connector for $275. Is this the correct style for a 71?

http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

[njsteve]

Originally Posted by Formulabruce

Steve, so if you put it in the head, and your gauge reads correct, what is the actual engine temp at the T stat with an IR gun? does it match???

My wedding anniversary is on Sunday in case anyone wants to buy me one, so I can check for you guys.

:-)

(One of these days I need to get one of those infra red contraptions)

[Lloyd-TX]

Originally Posted by njsteve

My wedding anniversary is on Sunday in case anyone wants to buy me one, so I can check for you guys.

:-)

(One of these days I need to get one of those infra red contraptions)

Congrats on your upcoming anniversary, Steve.
So - how long have you been "shooing her out of the kitchen"?

By the way, those infared thermometers are downright inexpensive these days. I'm fairly certain you can buy a name-brand one with the laser pointer for under $80.

[njsteve]

17 years of borrowing her kitchen utensils for automotive use. Hey, maybe I can get her the infra red tester as a kitchen device for testing the oven temp for accuracy.

Hey, Honey look what I got for you!.....

[70RAlll]

Originally Posted by Formulabruce

I agree with transamric, however, we need to look at a couple things
1. Steve that link to article is for a small block Corvette, look at the picture at the bottom with the teflon tape mythbuster!!
3. That said, the resistance in the GM sending units for guages was made to work where there was alot of heat sink, IE water around it in the top of the intake. I ran a 71 with guages and it always seemed hot, tried new senders, even letric, and similar results, then I moved the sender to the the intake for yuks, and put an infrared gun on it and bam it worked well, and correct'
4. These units for switching on an idiot light from the head, or turning on fans in newer cars work fine and head temp ALWAYS leads engine temp, unless ya own a 3rd gen LT-1. That said, I have never been able to nail down the guages correctly even with new GM sensors way back in 78 when my neighbor brought his pontiac over.
5. Conclusion, the senders from letric work perfect for 70-73 cars factory guages if you put the sender in the intake, by the thermostat, ( spark unit location on some)
I looked for a spec on the actual debth for the sensors of=r the actual length of them, and actually used a small extender in the head once, which I thought would be good but it heats up and no way to cool the metal, not enough water. Finally I firmly believe that GM had in mind using these in the intake for readings, look at their design, they are so close to hot metal near only 2 cylinder in a head .
If you get a sender for guages to read that your engine is at 180, and the sender is in the head, your probably running at a dynamic ( t stat open) temp of 160 . The thermostat is designed to control engine temp, makes logical sense to read the temp there.. I battled this on non chevy,GMC stuff for a bunch of years
PS not trying to stomp on any toes here....

I put an LL unit in the intake drivers side of water neck(OEM Position on 71 HO models) and it ran hot by 20 degrees or more. I still say, find an original one and use it. That is the only one that will work correctly with your guages. This friend of mine has 3-4 more used ones(at least he did last week).. He may sell them outright or ebay them..Just PM me guys.. I will see if he will sell any more outright..

[70RAlll]

Originally Posted by 70FormulaRAIII

Here is part # 1513321 - according to the NOS A/C Delco box - threaded without the round connector for $275. Is this the correct style for a 71?

http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

No that is not the correct one for a 71 HO engine. It should have a unthreaded "nail head" looking top piece..

[TA455HO]

Here, try this. Go to GMPartsDirect.com and enter in part number 12334869. $14.43 (plus shipping from them which can be brutal). It's likely not going to have the markings on the edge just above the threads, but it could function properly. Might even be USA components assembled in Mexico. But, if you aren't doing a concourse restoration it might be just the ticket. Here's the picture they show.



In the picture below from left to right are two old used ones, a correct NOS one with the stampings above the threads and one of the 12334869 pieces.

[njsteve]

The problem with the newer version from GM/AC Delco is that it is calibrated wrong and will make the gauge read high. The old ones are the ones to use if you can find them.

[Formulabruce]

Originally Posted by njsteve

17 years of borrowing her kitchen utensils for automotive use. Hey, maybe I can get her the infra red tester as a kitchen device for testing the oven temp for accuracy.

Hey, Honey look what I got for you!.....

wow, men with more imagination than me!!
Ill click off 20 years this wednesday, and I bought her something she has always been wanting... a Pontiac....
Solstice now I dont see her as much, and the garage actually has more room minus a car thats being driven hehe

[njsteve]

I ordered the infra red tester and told her about it. She is actually excited about the contraption! She loves kitchen gadgets. (now I'll probably have to order another for me).

[70RAlll]

Originally Posted by njsteve

The problem with the newer version from GM/AC Delco is that it is calibrated wrong and will make the gauge read high. The old ones are the ones to use if you can find them.

Steve...you are a "convert" now... old original units or none at all. It is just a waste of time and money looking for one that may work.. I know where 2 more of the correct used sender are, they are not dead on perfect, but will make the car read correctly if anyone cares.. I think the guy will sell these a bit cheaper since they are not perfect cosmetically.. And Steve can attest to this, I don;t make a penny selling these... just offering my help...

[Formulabruce]

Originally Posted by njsteve

I ordered the infra red tester and told her about it. She is actually excited about the contraption! She loves kitchen gadgets. (now I'll probably have to order another for me).

This is too funny!! my wife and I both worked in the restaurant business for years, she would
never fall for that, shes used the old style thermometers to death ( like you used to test the senders but industrial ones)
What is nice is you can point it at your kids forehead to check temp ( stay clear of the eyes)
Also can be used to find bees nests inside a wall, or siding, temp of your white paint in the sun Vs a dark color car.... etc..

[70RAlll]

I have found so many uses for my 2 IR temps guns- checking auto and/or home A/C flow temps, kid's temps, hot water temps etc.. just a handy gadget to have around the house...

[RicksGTO]

after following this post, I dug out the sender from my car that I believe is an original GM sender. It just has " - AC - Made in USA - 12 Volt " stamped in the neck above the threads, upside down. The gold cad/plating was pretty tarnished on it so I polished it with some course and then fine steel wool followed with some Mother's mag wheel polish and it looks almost as good as new. If it reads accurately, I'll be reusing it to see how accurate it is, will have to buy my wife the "cooking" thermometer as well to test it! Thanks for taking the time to post the sender test results Steve.

[Formulabruce]

Soon we will see if getting that gauge to read correct, is actually the engine temp at the goose neck
After years of messing with this, I found that 70RA111 is correct as far as getting the old units to make the gauges read right, BUT the thermostat controls temp and head temps run hotter,less water, less flow by that side, etc, so well see what the "gun" says .
If mine wasnt all buttoned up with dex cool installed I would do it myself and make a video.
Its all great info though, for sure.

[70RAlll]

Originally Posted by RicksGTO

after following this post, I dug out the sender from my car that I believe is an original GM sender. It just has " - AC - Made in USA - 12 Volt " stamped in the neck above the threads, upside down. The gold cad/plating was pretty tarnished on it so I polished it with some course and then fine steel wool followed with some Mother's mag wheel polish and it looks almost as good as new. If it reads accurately, I'll be reusing it to see how accurate it is, will have to buy my wife the "cooking" thermometer as well to test it! Thanks for taking the time to post the sender test results Steve.

Rick- that is the one you want, it will make cars with "guage package" temp. guage read correctly. The sender was used on GTO's as well as FB's from 70 and 71 I know, pretty sure 68-72 on all Pontiacs.. But without a doubt ...that is the good one.. And I could be wrong, but I think they were always just polished brass, with no gold plating.. could be wrong on that one.. Hold on to that unit, they are getting harder and harder to find in decent shape. And for whatever reason, the repo companies cannot make a correctly calibrated replacement... Also, I am still confused why 72 model years went to the head placement of the sender?? I pulled a dummy sender unit from the head of a 7/71 built formula 350 , but I always thought guage cars had that sender placed on drivers side of water neck in the intake manifold.I know 1970 and 1971 FB's did, RAIV,HO's and RAlll's.. only time I have seen a sending unit in the head on a Pontiac of this vintage was without guage package(i.e. idiot lights).. these senders rarely go bad...

[Formulabruce]

Originally Posted by 70RAlll

Rick- that is the one you want, it will make cars with "guage package" temp. guage read correctly. The sender was used on GTO's as well as FB's from 70 and 71 I know, pretty sure 68-72 on all Pontiacs.. But without a doubt ...that is the good one.. And I could be wrong, but I think they were always just polished brass, with no gold plating.. could be wrong on that one.. Hold on to that unit, they are getting harder and harder to find in decent shape. And for whatever reason, the repo companies cannot make a correctly calibrated replacement... Also, I am still confused why 72 model years went to the head placement of the sender?? I pulled a dummy sender unit from the head of a 7/71 built formula 350 , but I always thought guage cars had that sender placed on drivers side of water neck in the intake manifold.I know 1970 and 1971 FB's did, RAIV,HO's and RAlll's.. only time I have seen a sending unit in the head on a Pontiac of this vintage was without guage package(i.e. idiot lights).. these senders rarely go bad...

This is VERY CORRECT!!
I "think" that in 72 they were getting heat from the EPA and needed the temp control at the T stat , rather than drilling and tapping a second hole in the intake, they did the "Ill just take out the iodiot light switch and put it there" thing.
Science and common sense says that if a gauge unit works there and has the right resistances, its gonna be hard as hell to find.
I know Pontiac was cited in 72 model year for cheating on emissions, and so some stuff was changed.

[70RAlll]

Originally Posted by Formulabruce

This is VERY CORRECT!!
I "think" that in 72 they were getting heat from the EPA and needed the temp control at the T stat , rather than drilling and tapping a second hole in the intake, they did the "Ill just take out the iodiot light switch and put it there" thing.
Science and common sense says that if a gauge unit works there and has the right resistances, its gonna be hard as hell to find.
I know Pontiac was cited in 72 model year for cheating on emissions, and so some stuff was changed.

Unless the 72 HO's aluminum intake was different from the 71HO's or the </=71 iron intakes, there was no need to drill and tap a new hole. All the iron and Aluminum intakes from Pontiac I have seen have all had a tapped hole to the drivers side and to the passengers side of the water neck/thermostat. I have seen the drivers side plugged when a car had the dummy light sensor, which was in the drivers side head, otherwise, all Pontiac heads I have seen already have the tapped holes. BUT, I always say this..I know my 1970 and 1971 Firebirds all too well, I am rather ignorant when it comes to >72model years FB's.....SO maybe the 72 HO aluminum intake only had the transducer tapped hole on the passengers side.. I sort of doubt it. I recall seeing 72 aluminum intakes before with the same holes as 71's. I know I have had to drill a stuck plug out of at least 1 iron intake that came from a standard 400 engine with dummy lights..Those damn hex head plugs always are stuck and need drilling out after 35+ years of heat/cool down/rust...

[Formulabruce]

YUP thats right I didnt have the HO manifold in my head pictured there are 2 holes, however emssions switches were the 1st priority over gauges in Pontiac with the EPA on them, Excellent point 70RA!!