Help on 70 BB overheating issues.... - Chevelle Tech
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post #1 of 91 (permalink) Old Apr 22nd, 11, 1:23 PM Thread Starter
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Help on 70 BB overheating issues....

Fellas,

I need some help on my 70 BB. I have tried numorous things on my engine temp and I still can get her to stay where I want it.

Engine temps climb while in traffic or semi hot day. Temp on an 80+ days usually is around 205-220. There was one time when the gauge went up to about 240, going up a hill on a hot day. I had to pull over and let her cool down.

Let me tell you briefly the story behind this. I been dealing with the temps for about 2-3 yrs now. I get uncomfortable even driving the beast on nice sunny days.

I use to run those electric "Flex-a-lite" fans, but I noticed that while even running, the temp kept climbing. So I went back to the original 7 blade flax fan with no clutch on it, just the spacer. Put the original shroud back on, which the flex fan sits in the middle in and out of the shroud. Then I took out the t-stat, which I originally had the Stewart HP 160 t-stat. It helped it a little, but this was done when temps were around the low 70's. So the temp wouldnt climb, and if it did, it wouldnt hit 200.
Now that the temps are much nicer in the low 80's, I decided to go with just a regulare Autozone 160 t-stat. Then I decided to drive the beast to work. Well on the way home, there was a little bit of traffic, and temps were around 85-90 that day. I started to see the temp gauge climb and climb, from 190, 200, 210 and by the time i got home, it hit around 215-220. I shut her off and noticed she started to puke out coolant (I dont have a resevoir).

Now I just dont know what else to do. I wanna be able to just drive the beast even on warm nice days, but I am afraid I will overheat.

any suggestions?? will a Alum rad help me here?? or a different water pump?? Water Wetter?? Distilled water?? Tequila and alot of beer??

Currently on her is a 460 BB, Stewart Stage 1 water pump, Autozone 160 t-stat, 50 water 50 coolant, I run 91 octane, timing is at 16 base 34 total (eng dont like running 18 base 36 total), running orig shroud and 7 blade flex fan with spacer, Rad is a 4 core and is about 3-4 yrs old, there is a dent on the side of the rad, where the hose that goes into the intake is, but when i open the rad up, i can see the water moving and working......Everytime she gets around the 215 mark, I am usually at my destination and just shut her off and let her cool down.....

Well fellas, I hope some of you went through the same issues and can point me out some things I need to do.....I hate seeing her in the garage in nice warm days......

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post #2 of 91 (permalink) Old Apr 22nd, 11, 4:48 PM
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Re: Help on 70 BB overheating issues....

Quote:
Originally Posted by mad70ss View Post
Fellas,

I need some help on my 70 BB. I have tried numorous things on my engine temp and I still can get her to stay where I want it.

Engine temps climb while in traffic or semi hot day. Temp on an 80+ days usually is around 205-220. There was one time when the gauge went up to about 240, going up a hill on a hot day. I had to pull over and let her cool down.

Let me tell you briefly the story behind this. I been dealing with the temps for about 2-3 yrs now. I get uncomfortable even driving the beast on nice sunny days.

I use to run those electric "Flex-a-lite" fans, but I noticed that while even running, the temp kept climbing. So I went back to the original 7 blade flax fan with no clutch on it, just the spacer. Put the original shroud back on, which the flex fan sits in the middle in and out of the shroud. Then I took out the t-stat, which I originally had the Stewart HP 160 t-stat. It helped it a little, but this was done when temps were around the low 70's. So the temp wouldnt climb, and if it did, it wouldnt hit 200.
Now that the temps are much nicer in the low 80's, I decided to go with just a regulare Autozone 160 t-stat. Then I decided to drive the beast to work. Well on the way home, there was a little bit of traffic, and temps were around 85-90 that day. I started to see the temp gauge climb and climb, from 190, 200, 210 and by the time i got home, it hit around 215-220. I shut her off and noticed she started to puke out coolant (I dont have a resevoir).

Now I just dont know what else to do. I wanna be able to just drive the beast even on warm nice days, but I am afraid I will overheat.

any suggestions?? will a Alum rad help me here?? or a different water pump?? Water Wetter?? Distilled water?? Tequila and alot of beer??

Currently on her is a 460 BB, Stewart Stage 1 water pump, Autozone 160 t-stat, 50 water 50 coolant, I run 91 octane, timing is at 16 base 34 total (eng dont like running 18 base 36 total), running orig shroud and 7 blade flex fan with spacer, Rad is a 4 core and is about 3-4 yrs old, there is a dent on the side of the rad, where the hose that goes into the intake is, but when i open the rad up, i can see the water moving and working......Everytime she gets around the 215 mark, I am usually at my destination and just shut her off and let her cool down.....

Well fellas, I hope some of you went through the same issues and can point me out some things I need to do.....I hate seeing her in the garage in nice warm days......
try running with no t/stat as a test .. thin the coolant to 70% water 30% coolant .. if the issue persist , it may be time for a aluminum rad .

the old rad could have seen better days .. partly pluged and so on .
Don
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post #3 of 91 (permalink) Old Apr 22nd, 11, 5:23 PM
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Re: Help on 70 BB overheating issues....

Put a factory clutch on the fan instead of just the spacer. Go to a 180 thermostat. I have a 70 454 4 speed Monte with a/c, a stock shroud & radiator and and live on the East Coast with humidity in the summer. I NEVER overheat. There is a mark on the side of my radiator about 3-4" down from the top of the radiator cap. That is the full mark when cold. If you fill past that, it will puke on the ground when it gets hot. Unfortunately I'm a real believer on following what the factory did for a couple of reasons. 1, they had highly paid, college degreed engineers working this stuff out and 2, they had to warranty the cars. Just my opinion, but it works for me.
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post #4 of 91 (permalink) Old Apr 24th, 11, 1:59 PM
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Re: Help on 70 BB overheating issues....

My driver is a 70 SS 454 Sta. Wgn. with A/C. The cooling system is 100% --1970 (AKA) VO-1 or H.D. with every piece the factory installed. ALL the rubber pieces, 772 blade & shroud and a new style G.M. clutch that fits the 772 blade,Splash guards ( they keep air from entering the engine bay.) 1970 Chevelles are designed to have the outside air enter through the frontal area and exit ONLY by the lower left & right exhaust manifolds.
Any airflow disturbance will cause burbles or hot air spinning under the hood. When the hot air stays under the hood, It can lead to overheating and or vapor lock. The outside air MUST pass thru your HEAT EXCHANGER ( Rad.) and EXIT at the rear.
On a hot day in Tenn. high 90s with the A/C running my 30 over 454 will climb to 210-215. The cooling system in your car worked 40 years ago, Something is a-miss. Note: ALL of the Mfgs ( G.M.-Ford-Mopar ) in the 60-70s had Designed Clutches & Fan blades for the BIG Cu. In. engines. With a good Rad. and all the factory parts and pieces, I believe you should be fine. I like the factory stuff, It has a 40-50 year track record. For me it works fine.
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post #5 of 91 (permalink) Old Apr 24th, 11, 2:16 PM
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Re: Help on 70 BB overheating issues....

Sensor in the head or intake.
Put a sensor in the intake as the head has little airflow around it at stop/idle and see if it stabilizes.
I wouldn't bother trying to remove the old sensor just yet ,just put a new one in the intake and wire to it.
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post #6 of 91 (permalink) Old Apr 25th, 11, 10:57 AM Thread Starter
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Re: Help on 70 BB overheating issues....

update....
The temp sensor is on the intake, I had relocated it when the engine was built from the block to the intake.

Ok, so I took out the spacer and the flex fan. Went with the 772 7 blade fan and also an Hayden HD fan clutch and installed a HP 180 t-stat. Weather was low 70's all weekend so I really couldnt really see what she would do on hot days. But still took her out. 1st I let her sit on idle for a good 20 min, did not move from 185. The took her out on a 20 min cruise through the city. I tried to find a street with alot of traffic, but wasnt lucky of all days. While cruising on the streets with light traffic, she did well, I think she was around 180-190. Then I took her up this small hill, maybe about a mile long, just cruised it up hill, didnt really get on her. Though she did creep up to about 200-205. But as soon as I started going down hill and all the way back home she came down to 180-185 again.
It is supposed to be getting warm this coming weekend. So will see what she does then.

I am thinking of going back with the Mr Gasket HP 160 t-stat and trying that out and see how she does with the 7 blade and fan clutch. Though I think the 7 blade is much better than the flex fan, I think the flex fan was flattening out to soon and not pulling enough air at low speeds, since this was the speeds she would heat up. While driving about 10-35 mph, 1200-2000 rpms. Because if I was going down the highway at 50 mph or more, she wouldnt heat up. she would stay at 200-205.

Don,
I really dont think its the radiator. Its only about 4 yrs old, its a high efficiency 4 core radiator that I bought from OPGI. When I have the rad cap off, I can see the coolant running. Though I am thinking of dumping all that coolant out, going with destilled water and a bottle of that water wetter pink stuff. See if that would help me also.

any more suggestions fellas??

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post #7 of 91 (permalink) Old Apr 25th, 11, 12:58 PM
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Re: Help on 70 BB overheating issues....

I have a 70 454 Chevelle and a 67 502 Impala. Both had overheating problems. Switching from copper/brass radiators to aluminum rads dropped the running temps by 20 on both cars. On the Chevelle I run the factory 7 blade fan, shroud and Hayden replacement fan clutch, Edelbrock alum W/P and SW hi flow 180 thermostat - runs @ 185 all day. The Impala has a dual Flex-A-Lite puller fan, Edelbrock alum W/P and SW hi flow 180 thermostat and required more work including swapping pulley sizes to run the water pump faster - still doesn't deal with heavy traffic as well as the Chevelle.
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post #8 of 91 (permalink) Old Apr 25th, 11, 2:17 PM Thread Starter
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Re: Help on 70 BB overheating issues....

After reading a few posts by Scott "SWHEATON" I am going to switch from my stock 70 BB fan shroud to a 71 BB stock fan shroud.

It is supposed to be in the mid to high 80's tuesday and wednesday. Going to try that shroud and go from the 180 t-stat to a 160 t-stat and see how she does.....

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post #9 of 91 (permalink) Old Apr 26th, 11, 11:14 PM
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Re: Help on 70 BB overheating issues....

Quote:
Originally Posted by mad70ss View Post
After reading a few posts by Scott "SWHEATON" I am going to switch from my stock 70 BB fan shroud to a 71 BB stock fan shroud.

It is supposed to be in the mid to high 80's tuesday and wednesday. Going to try that shroud and go from the 180 t-stat to a 160 t-stat and see how she does.....
============================================

Ralph, many things make a motor run hotter,not running a vac adv,retarded base timing,lean fuel calibration in carb,no shroud ,or worng fan (maybe your flex fan) for stock shroud being run,worn out fan clutch if running one,bad-worn out tired rad just to name a few.

Anyway,you can cool a 500-550hp + bbc 70 chevelle no prpblem with a PROPERLY setup stock cooling system and also a proper tuned/dialed in motor too.

My 69 with mild perf 396 which is same basic setup using same shorud/rad/ra /fan clutch in 95deg HHH temps last summer IT ran 178-180 max at cruise and 180-185 MAX in traffic,never saw 190 deg in traffic in 95 deg HHH heat.

In 70-80 deg temps it runs 172-175 at cruise and 175-178 in traffic,the mottor repsonded very well to running thses cool temps.

BTW,those temps are with temp sender in stock location driver side head by hot ex port/ex valve and not in the intake that generally reads cooler.

Heres my setup,if you copy it exactly as i set it up and ensure your running plenty of base timing like 18 deg or so with aftermarket cam and vac adv to full int vac with cvarb not too lean you will get good reults. .

* Basically stock 69 396/350hp running approx 9.8-.9 comp with a mild hyd ft perf cam with 222/226 deg dur @ .05 ,.525"/.525" gross lift,112 deg lsa, stock type ex with 50 series flow masters & 2.5" mandrell bent pipes,q-jet with stock intake,stock ex manifolds that are extrude honed for as little more umph,stock lrg oval port 063 heads,etc.

* AL STOCK WEATHERSTRIP/INNER FENDER SPLASH GARDS/COWEL SEAL/ETC ARE INSTRALLED

* 70% DISTILLED WATER 9REDUCED CORROION IN RAD-COOLING SYSTEM -ENGINE BLOCK)/30% COLLANT MIX FOR BEST HEAT TRANSFER WHEN STILL USING TRADITIONAL COOLANT AND NOT JUST DISTILLED WATER BY ITSELF.

* GM 772 7 BLADE CLUTCH FAN USED BY GM FOR AC OPTION & ALSO HD COOLING OPTION.

* PROPER SIZE STOCK PULLEYS FOR FAN/WATER PUMP/CRANK ENSURING PROPER FAN-WATER PUMP SPEED.

* HAYDEN 2747 HD/GM HD COOLING OPTION TYPE FAN CLTUTCH,NOT A STD DUTY FAN CLUTCH THAT DOESNT PULL AS MUCH AIR THRU THE RAD THAT DOESNT COOL AS WELL IN SOME APP'S ESP IN TRAFFIC/AT IDLE & WHEN AT SLOWER ROAD SPEEDS WHERE THERE ISNT ENOUGH NATURAL AIRFLOW THRU RAD FPR PROPER COOLING .

* STOCK SHROUD.

NOTE:I ALSO INSTALLED SOME BLK COLORED ADHEASIVE BACKED FOAM INSULATION INBETWEEN RAD CORE AND SHORUD TO CLOSE OFF THE FACTORY GAP (BY DESIGN) INBEWEEN RAD & SHROUD.

DOING THAT ENSURES ALL AIR PULLED BY FAN GOES THRU THE RAD AND NOT HALF OF IT BEING RECIRCULATED HOT SOGGY AIR FROM UNDER THE HOOD WHICH IS WHAT HAPPENS IF YOU DONT SEAL UP THE GAP BETWEEN SHROUD AND RAD CORE SO FAN CAN PULL MORE COOL AIR THRU THE RAD CORE FOR PROPER COOLING.

* OIRIGNAL STOCK 3 CORE HARRISON RAD RESTOERED WITH A HD-HI EFFICIENCENCY 4 CORE THAT FITS THE STOCK HARRISON 3 CORE TANKS.

* MILODON HI FLOW W-PUMP WITH HI PERF CATS IRON IMPELLER WITH CLOSED BACK.

NOT THE COOKIE CUTTER STAMPED STEEL STAR SHAPED OPEN BACK IMPELLER MOST NEW STD FLOW CHEPER PUMPS MFG'D TODAY HAVE. THEY DONT ALWAYS PUMP WELL DEPENDING ON BACKPLATE TO COOKIE CUTTER CLERANCE WHEN OS OFTEN TOO MUCH RTESULKTING IN CAVITATION SIGNIFICANTLY REDUCING COOLANT FLOW.

BTW,back in 69-70 all the bbc/sbc stock cast iron waterpumps came with the closed back hi perf type cast iron impellors that pump/move coolant better then most cheaper rep pumps with cookie cutter stamped steel type impellors.


* 19-20 DEG BASE + 18 DEG MECH ADV IN BT 2500-2600RPM FOR 38 TOTAL + VAC ADV LIMITED TO 12 DEG MAX FOR 50 DEG TIMING AT CRUISE.

* RUN VAC ADV TO FULL INT VAC ALL THE TIME ,EHLPS RUN COOLER IN TRAFFIC AT IDLE AND ALSO HELP OFF IDLE POWER/THROTTLE RESPONCE TOO.

* CAN'D THE 2 BRAND NEW BUT DEFECTIVE HI FLOW STATS I HAD IN A ROW THAT WOULD NOT FULLY OPEN RESTRICITNG COOLANT FLOW MAKING MOTOR RUN HOTTER THEN IT SHOULD AND INSTALLED A STD FLOW AUTOZONE 160 DEG STAT(pt#-15356) I DIRLLED A COUPLE BYPASS HOLES IN TOO. IT COMES WITH A VERY SMALL BYPASS VALVE IN IT BUT ITS SO SMALL I DECIDED TO STILL DRILL 2 ADDITONAL BYPASS HOLES TO SPEED UP GETTING AIR OUT OF COOLING SYSTEM,WORKED GREAT.

I have also read hear in team chevelle of other people having issues with the hi flow stats that most of which are now being mfg'd outside the USA where quality took a dump,i was using them for many yrs but will not use them anymore.

The 2 bad stats in a row had me chasing my tail on my own car form a while with its current setup that i knew should be running much cooler then it was at the time thinking it could not be 2 bad hi flow stats in a row from 2 different mfgs & 2 different stores when in fact 2 bad/defective hi flow stats was the problem from the begining which the std flow autozone duralst pt#-15356 stat fixed.(UMPH!!!!/LOL!!!)

Again,in 95 deg HHH hot soggy air this setup runs 178-180deg max at cruise and 180-185 MAX in traffic with my BBC,it never saw 190 deg in traffic or at cruise in 95 deg HHH soggy heat.

In 70-80 deg temps it runs 172-175 at cruise and 175-178 in traffic,the mottor repsonded very well to running thses cool temps.

In 45-60 deg temps it runs 168-170 at cruise and 172-175 max in traffic,but also gave decent/plewnty of heat in 45-50 deg temps which surprised me .

I have also installed this same setup in a few other 69/70 bbc chevells for people having running hot issues significantly reducing the operating temps making the owners happy campers.

Add one of Dons/Alumitechs very stock looking custom built AL rads to my setup stated above and it can be even better.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)

Last edited by SWHEATON; Apr 26th, 11 at 11:37 PM.
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post #10 of 91 (permalink) Old Apr 27th, 11, 12:34 PM Thread Starter
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Re: Help on 70 BB overheating issues....

Thanks for the info Scott

I have been reading a few posts on this subject and you do point out alot of good info.

I have been battling the heat issue for about a 2 yrs now, off and on.

I had on there a dual flex-a-lite electric fans with a Mr. Gasket 160 t-stat. I hated this set up, yes it looked pretty and clean, but wasnt cooling at all. I wouldnt even drive her on warm days, because it for sure will heat up around 215-230.

Then about a few months ago, I took out the electric fans out, installed a Flex fan, spacer (no clutch) and left the 160 t-stat on, she did better, but during this time, weather was a bit cool in the high 60's, but she would heat up in traffic to about 210-220. I took out the t-stat, and she did a little better, 190-210, but then again, it wasnt warm out, it was actually cold in the mid-high 60's.

Finally after reading some posts of yours, I finally decided to go with the Hayden 2747 Clutch that a friend of mine had laying around, and also installed the 7 steel blade fan and got me a 71 shroud from Muscle Factory. I threw on the 160 t-stat back in.

I brought her to work today, it is suppose to be in the high 80's today, so this would be a perfect time to test her out. New clutch/772 fan/71 shroud/160 t-stat. I will be sitting for sure in traffic in stop and go for a good 30-40 min. So i think this will be a good test.

Here is my timing on her:
I have an MSD e-curve Dist., MSD blaster coil, MSD 6AL ign box,
No vac advance.
I have the timing set at 34 total. I tried bump it up to 36-38 and for some reason, she wasnt sounding good. maybe i am doing something wrong?

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post #11 of 91 (permalink) Old Apr 27th, 11, 1:52 PM
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Re: Help on 70 BB overheating issues....

hey Ralphy, been following your thread. How did she do today with all the changes?


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post #12 of 91 (permalink) Old Apr 27th, 11, 5:03 PM
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Re: Help on 70 BB overheating issues....

Quote:
Originally Posted by mad70ss View Post
go from the 180 t-stat to a 160 t-stat and see how she does.....
I read the above often. Thermostats have nothing to do with controlling maximum operating temperature. I see Scott has good advice and you can also add John Hinckley's cooling article to his info. http://www.camaros.org/pdf/corv_cooling2.pdf

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post #13 of 91 (permalink) Old Apr 27th, 11, 11:47 PM
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Re: Help on 70 BB overheating issues....

Greetings from Arizona
I bought a 66 Lemans last summer here in Tucson AZ, It had electric water
pump, electric fan with schroud, and flow restrictor instead of thermostat,
Engine is 468 Pontaic, alum heads, it would go to 240 and beyond within 5 miles of 55 mph, or 10 min driving and forget sitting at a light, it was shut off and let fan and water pump run to help cool it down before driving again, I first tried 195 thermostat, it helped , then stock water pump, better, the stock style fan, no fan clutch, and home made fan schroud. now runs 195 even in summer time heat, in traffic or cruising.

anther thing, TEST your readiator caps for proper pressure, I got about 10 new rad caps last year the wouldn't hold 1/2 there pressure. water boils at 212 degrees, water boils with 15 psi pressure at about 250 if my memory serves me....I am older then dirt....Jay


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post #14 of 91 (permalink) Old Apr 28th, 11, 12:48 PM Thread Starter
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Re: Help on 70 BB overheating issues....**UPDATE**

Yesterday I brought my Chevelle to work, which I live about 30 min away with no traffic, but with traffic it takes me about an hr to get home.

Ok this is what I did lately to her, I installed the correct 772 7 blade fan with an HD Hayden 2747 clutch fan. I also threw on the Mr. Garsket 160 t-stat I have (I actually have 3 t-stats, Mr Gasket 160 & 180, and a Autozone std 160 t-stat). I also removed the correct 70 shroud and replaced it with a 71 shroud (covers the radiator good, the 70 doesnt cover the whole radiator).

Yesterday's outside temps were around the mid 80's, perfect weather to test her out. and to top it all off, I actually hit some heavy traffic due to a couple of accidents.

Now I am going off the factory gauge, which this is what I think the Temp Gauge reads 100, 127.5 (1st line after 100), 155 (2nd line), 182.5 (3rd line), 210, 220 (1st line after 210), 230 (2nd line), 240 (3rd line) and finally 250. (is this about right?? Are these the temp numbers on the factory gauge??)

I know I should install another mechanical temp gauge, which I do have, but I havent installed it.
If memory serves me right, the factory gauge is right on. I did check it with the IR gun and it was very, very close to the factory temp gauge reading.
So I am on stop and go traffic around 4pm, outside temps are in the mid 80's. The temp gauge was reading between the 155 (2nd line) and 182.5 (3rd line). Then the traffic opened up a few miles, the temp gauge stayed a hairline under the 182.5 (3rd line). Then I hit traffic once again, and I am 4 exits away from my exit, which is around 4-5 miles. She started to heat up a little, she went lets say a hairline or two above the 182.5 (3rd line) all the way until i made my exit off the fwy. Got home, parked her in the garage and temp was reading a hairline under the 182.5 (3rd line). Shut her off, then a few minutes later, she started to puke out some coolant. Now I am confused, i thought it will only puke out the coolant if the coolant boils at 212? is that right??

I am going to get me a new IR gun, since my son brought the one I had. I will double check the readings again, and install the other mechanical gauge I have, just to be on the safe side.

But all in all, I am very pleased on how she performed . Before if I was stuck in a 5-10 min of traffic, it would definately hit the 210 easily, it would even hit the 1st line after the 210, which i believe its 220.

This time, i didnt hit the 210. I believe she max'd out probably around 190, and this is in stop and go traffic in mid 80's heat.

This morning I brought her back in to work, now I switched the t-stats. I took out Mr.Gasket 160 t-stat and replaced it with an Autozone 160 t-stat (I drilled 2 extra holes in it to help with the air).
Temps today should be around the low to mid 80's. Now will see how she does with just a standard Autozone 160 t-stat.

So what you think fellas? am I reading the factory gauge right??

_____________________________________
Ralphy
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post #15 of 91 (permalink) Old Apr 28th, 11, 1:49 PM
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Re: Help on 70 BB overheating issues....

I think she will loose fluid when ever it is to full. On my 66 the coolant just covers the top of the rows, about 1 1/2" of air space. When coolant heats it expands, you have to have room or it will spill out though the overfill hose. Unlike todays cars that have an overflow tank. Also after car shuts off, engine temp will rise quite a bit causing the coolant to expand more, so while driving you may have no problem, then when you shut the car off, coolant increases in volumn and then overflows. Who know if your guage is reading correctly, you could add a second guage. I wouldn't get to mad as your name suggests.

By the way, it's snowing her in MN, so no driving today.


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Jim_66SS is offline  
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