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njsteve · 11:12 PM

The 72 intake only has the one hole for the thermostatic vacuum valve drilled out and tapped. The other boss is not tapped. This was one of the main differences betwen the 71 and 72 intakes. The second major difference are the different bosses for the 72-only throttle cable bracket. Third difference was the cast iron heat crossover had a different choke riser that went from front to back instead of left to right like on the 70 and 71 engines. It also had a different exhaust heat riser port layout to match up with the exhaust heat riser on the 72 HO heads.

70RAlll · 08-03-2010, 03:50 AM

Quote:

Originally Posted by njsteve

The 72 intake only has the one hole for the thermostatic vacuum valve drilled out and tapped. The other boss is not tapped. This was one of the main differences betwen the 71 and 72 intakes. The second major difference are the different bosses for the 72-only throttle cable bracket. Third difference was the cast iron heat crossover had a different choke riser that went from front to back instead of left to right like on the 70 and 71 engines. It also had a different exhaust heat riser port layout to match up with the exhaust heat riser on the 72 HO heads.

Steve thanks for showing this. I learn something new daily. Never had seen that 72 did not have provision for the intake water temp sending unit. Thanks...

Formulabruce · 08-05-2010, 11:41 PM

Quote:

Originally Posted by 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!!

HMm, Im glad I saw Steve intake picture, when I was gathering parts I bought the wrong intake.
This all makes sense now though....one hole and no gauge sender there. Emission>gauges for pontiacs troubles with the EPA that year

unruhjonny · 08-10-2010, 03:41 PM

Quote:

Originally Posted by njsteve

...
And of course on the return trip it seemed that everyone in the area who had a lawnmower, was out trimming their gravel as I tried to drive by.

ha-ha-ha!!

unfortunately I know exctly what you mean..

Quote:

Originally Posted by njsteve

OK, just got the original, vintage 1513321 temp sender from 70RAIII, here is the updated chart:
...
Looks like the Wells sender is pretty darn close to the original GM sender's specs. I'd say it's a dead-on match given my pot of hot water on the stove, scientific method.

BAH-HA-HA!!

Quote:

Originally Posted by njsteve

The 72 intake only has the one hole for the thermostatic vacuum valve drilled out and tapped. The other boss is not tapped. ....

crap!!

Here I was going to actually try to help & contribute to the thread, and you seemed to have stopped joking (or doing kitchen experiments) long enough to have beaten me to it!!

Norwood · 09:11 PM

Before the big caravan up to Gus's http://forums.maxperformanceinc.com/...=666530&page=7

I thought that I would see if I could get my temp gauge on my 70 T/A to read a little more accurate. With the sender that was installed the normal reading was 210 and I just got tired of looking at that. I went to my local Autozone and picked up the NJSteve recommended Duralast TU5, well as my luck has it the normal reading is now 230. My next step I guess will be to find someplace that sells the actual Wells TU5 boxed unit and hope for the best.

Anybody have any other suggestions other than putting the old sender back in or paying a stupid price for an NOS 1513321 . The one I took out has no markings on it so I don't know what kind it is.

on water cross over at temp sender

On radiator tank

Formulabruce · 07-08-2011, 09:35 PM

The resistance in your sender is a bit low ( causing gauge to read higher. Since its not a fast response gauge you could put a resistor in line, 1/4 watt, 10 ohm resistor for starters to test. keep it off the manifold.
Once you get the right combo, add the resistance of your resistor to the sender in there now and look for a sender with that resistance ( carry a meter)
just my 2 cents

njsteve · 07-08-2011, 09:41 PM

Norwood, I can loan you my TU5 to compare if you want.

Here's one on ebay for $7.
http://cgi.ebay.com/ebaymotors/WELLS...-/170658762235

BTW, 70RAIII sent me a really nice used original GM sender, very reasonably. That's what I have in my car now. I think he recently posted that he has a few more on his shelf.

Norwood · 07-10-2011, 02:29 PM

I knew that I had a set of heads from my 75 Formula in the garage someplace so I went looking for them and found them. The sender was still there, pretty exciting. I pulled the sender, cleaned it up and that is when I noticed that the black plastic insulator was cracked. I don't know if it will work but I will soon.

It cleaned up well, the markings on it are, AC-MADE IN USA-12 VOLT

Crack in the insulator

njsteve · 07-10-2011, 02:50 PM

It should work ok. Remove the teflon tape though, it affects the ability of the sender to get a good electrical ground to the head.

Norwood · 07-10-2011, 03:23 PM

Took off the tape, as per Steve. Put it in, started it up and waited about 10 minutes and here is what I have. I don't know if it is accrate but atleast it dosen't look like its overheating when its not.

Thanks Steve, Bruce and Bill Oxley who emailed me this morning that he would send me a good one on Monday. Thats why this place is simply the best. I have never met any of you on a personal level but help is always just a key stroke away.

njsteve · 07-10-2011, 03:59 PM

Mine runs at the first notch, even with the a/c running. It has the original 4-speed radiator (no internal trans cooler) recored with a three row copper core by a reputable local radiator shop. I performed the same temp checks as you did and my radiator readings were about 20 degrees lower than yours on both sides. The intake crossover was around 190.

unruhjonny · 07-10-2011, 06:41 PM

I agree that this forum rocks!
(or at least from what I hear, as long as you don't hang out in the 'lounge' :lol

70RAlll · 07-11-2011, 08:44 PM

Quote:

Originally Posted by Norwood

Took off the tape, as per Steve. Put it in, started it up and waited about 10 minutes and here is what I have. I don't know if it is accrate but atleast it dosen't look like its overheating when its not.

Thanks Steve, Bruce and Bill Oxley who emailed me this morning that he would send me a good one on Monday. Thats why this place is simply the best. I have never met any of you on a personal level but help is always just a key stroke away.

Yes Craig, your original sender went out today. It almost looks NOS... You will be pleased... You should have it in 2 days via UPS..

Bill

Pepi · 07-11-2011, 09:20 PM

Quote:

Originally Posted by njsteve

It should work ok. Remove the teflon tape though, it affects the ability of the sender to get a good electrical ground to the head.

I always heard that too, about no tape on the threads, but the link from one of your other posts shows it doesn't really effect it.
http://www.lbfun.com/warehouse/tech_...eCF-Thread.pdf

njsteve · 07-18-2011, 07:36 PM

Norwood, I just took my Gramma's 75 Firebird out for a spin in the 97 degree heat, with the A/C on. Using the same infrared monitor you have I got 190 at the pass side tank, 210 at the crossover and 210 on the driver's side tank. I have an autometer mechanical gauge and it read accurately at 210.

She has been running hot since the rebuild. I have about 600 miles on the engine at the moment. The radiator was a brand new, aluminum 4-core I installed two years ago. With the original, unrebuilt 78,000 mile engine, it ran at 160, even in the heat.

I think the new engine is just a bit too tight and is generating a little too much heat for the aluminum radiator to disperse and I may just have my local radiator guy recore my original 3-core copper radiator. He did a great job on my 72's original radiator. That car runs 170 in the same heat with the A/C running full blast.

Norwood · 07-18-2011, 09:31 PM

On our trip up to Wisconsin
http://forums.maxperformanceinc.com/...666530&page=11
over the weekend it ran all over the gauge. Normal driving it was just above the 1st line at 65-80 it would go up to the middle line. If I sat and idled for a few minutes it would creep up past the middle. Its is the original Radiator that was re cored about 10 years ago, I never looked, I hope that it is a 4 core. The car ran GREAT and seemed to get pretty good mileage.

I was thinking maybe I might go with one of these Aluminum radiators.

https://secure.wf-api.com/www.alumit...ual-trans.html

njsteve · 07-18-2011, 09:49 PM

Stick with copper as it transfers heat better than aluminum and will run cooler.

Formulabruce · 07-18-2011, 10:25 PM

Quote:

Originally Posted by njsteve

Stick with copper as it transfers heat better than aluminum and will run cooler.

X2 , Flush yours Craig, or make sure theres no "DEXCOOL" in there cloggin it up!

Norwood · 07-18-2011, 10:37 PM

I just might do that Bruce. I read that I should use a lower percentage of Antifeeze to water like 20%. What do you guys think?

Formulabruce · 07-19-2011, 12:18 AM

It will cool better, with 20%, just check it before winter storage.
My gauge said 220 at first ( stock CR 8.2), E head, and 468XE cam, RA exhaust)
I got an old original from a junk yard and it runs at first mark with a 160 T stat.
temp at T stat housing runs 175-180 ( IR)
So on this half sweep factory gauge, anyone have the number for the first line?, or what it was intended to be,( besides a ball park) has to me more than half or 155 degrees ?

EDIT, I have 1970 Gauges in my car

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