[chiphead]

It's all in the combination and intent. While a full-race 496 might run great with locked timing for being consistant, a street 389 is gonna run like ***** with locked timing due to low RPM overadvance.

What works for me may not work for others. But I've found that running as much base timing as possible without starter kickback and then 36* total works best for my street/strip engines. The ideal is to have peak cylinder pressure at 12-14* ATDC, which is a function of basic physics, not choice. This means picking a base timing that approaches the ideal at idle, then lighting the mixture earlier and earlier as RPM increases. The rate of the optimal advance for any one engine depends on the parts chosen for that one engine and what that engine is asked to do.

Since a street engine is loaded by moving the car between 1000-4000 RPM, that is where we care what the rate and amount of advance is.

[67bonnie455]

I think it is too hot if your gauge is correct.


I am concerned about the pump. When you pulled it, did you note the condition of the seals on the two tubes that go into the cover? If you pull the pump, make sure they are in good shape and in contact with the divider plate. Jim Hand's book has some good info on optimum clearance for the vane and the plate if you want to check it. Get a good pump with the original large cast iron vane. If you pull a couple of inches of water out the ratiator and bring the motor up to 1500, there should be strong streams out of visible cores (with themostat open). Becareful, it may puke hot water on you when you close the throttle to idle.

There is a lot of good advice here for you on timing and such. I agee with all of these:
Go with a 180 or lower themostat (but after 200, yours should be open).
Set timing correctly.
Get a shroud on the fan; it pulls the air throught the radiator.
Make sure the radiator cap is good and break the motor in some more. The motor I just finished run hotter than I liked for a couple of hundred miles.

Last thought; I have gotten so many bad parts lately that I would not be surprised if it was a bad thermostat not opening up completely or a thermostat with too small of a valve opening (wrong application of a one all fits all unit). It is getting hard to get correct application parts as noted.


The 75-79 carbs were lean. Once you get it running cooler, you may like fatting up the power valve for more midrange power. The carb base gasket and intake carb plate are restricted and not allow the secondaries to open up completely. Easy to fix.

Hope this helps.

[GOAT8U2]

Apparently you're not running vacuum advance if you're wondering how to get to 24 degrees at 1200rpm.

I have 33 degrees WOT at 2500rpm, I then added 15 degrees of vacuum advance so while cruising, I'm seeing 48 degrees of advance around 2500rpm. I gun it at 3k just to make sure my springs have completely expanded by then. Great for mileage, cooling and response.

[PunchT37]

Good operating temps are 175 at least to 210.
You`ll prolly find that that engine will start to run cooler on it`s own as it breaks in and the new engine friction goes down.

[SRR]

Originally Posted by 67bonnie455

I think it is too hot if your gauge is correct.


I am concerned about the pump. When you pulled it, did you note the condition of the seals on the two tubes that go into the cover? If you pull the pump, make sure they are in good shape and in contact with the divider plate. Jim Hand's book has some good info on optimum clearance for the vane and the plate if you want to check it. Get a good pump with the original large cast iron vane. If you pull a couple of inches of water out the radiator and bring the motor up to 1500, there should be strong streams out of visible cores (with thermostat open). Be careful, it may puke hot water on you when you close the throttle to idle.

There is a lot of good advice here for you on timing and such. I agee with all of these:
Go with a 180 or lower thermostat (but after 200, yours should be open).
Set timing correctly.
Get a shroud on the fan; it pulls the air through the radiator.
Make sure the radiator cap is good and break the motor in some more. The motor I just finished run hotter than I liked for a couple of hundred miles.

Last thought; I have gotten so many bad parts lately that I would not be surprised if it was a bad thermostat not opening up completely or a thermostat with too small of a valve opening (wrong application of a one all fits all unit). It is getting hard to get correct application parts as noted.


The 75-79 carbs were lean. Once you get it running cooler, you may like fatting up the power valve for more midrange power. The carb base gasket and intake carb plate are restricted and not allow the secondaries to open up completely. Easy to fix.

Hope this helps.

I like my cars set up for worst case scenarios. I like 160 degree t-stats. T-stats establish the MINIMUM temp the engine will be at not the maximum. I like to see my engine temps "around" 180 degrees. On a hot day stuck in traffic I don't want to start at 210. I don't see much of a buffer zone there.

[Milwxman]

I put a Mr. Gasket 160 high-flow thermostat in the car. Still have the same problem. Kind of expected it. I think that the engine is making more heat than the radiator can dissapate.

It is a three core. The car had an original 326 and this is the original radiator. What radiator did the GTO 389 or 400 come with?

Also another thought that was brainstormed was this is a 77 block and it was bored .040 over. It could be making more heat than the original radiator could handle. (Makes sense). SOOO I think that I might need to invest in a bigger radiator.

I just want to get this thing running without worrying!

[Milwxman]

Another thing, Could a bad damper pulley or wrong damper pulley cause this problem?

[67bonnie455]

As long as the pulleys are stock Pontiac, they should be turning the pump at the correct rate. Boreing is not going to make it produce more heat.

It being a 326 car makes me think the radiator is too small. A three core is usually enough, but it depends on the size of the tanks and the area of the core. You can do some searches to see it this is the case versus a 389 HO raditor, but research won't make it run cooler. If you have good flow through the one you have and the motor is timed correctly, get a 500 hp aluminum to replace it. You can sell your radiator.

I am glad you are taking steps to cool off the motor.

When you get it running cooler, check the carb base gasket for a semi-circular secondary opening and a closed off top of your intake. Lot more power waiting for you...

[Milwxman]

My father-inLaw came over the other day and helped me time the car by performance. Seems that it was a ways off. Now that it is timed better, it seems to be running a little cooler. Took it out yesterday and stayed around 190 - 195 and jmped to 200 when on highway unning 75-80 mph. Temp dropped to 190 once I slowed down. The other factor is that the weather has been cooler too. Timing slipped a little again and I am going to re-timed and lock it down. I am liking the new timing. I think since I have the different harmonic balancer on it the timing lines do not match up right.

Thanks everyone for your help.

[71 T/A]

If your car runs hotter on the highway than all likelihood, you need a bigger radiator. In every instance when I had that problem, a bigger radiator solved it by running cooler.

[Region Warrior]

All pontiac V8's used 195 stat's since 66.
210-215 operating temp was/is normal.

On newer cars e-fans dont kick on till 230-240.

[Z Code 400]

Originally Posted by Region Warrior

"All Pontiac V8's used 195 stat's since 66.
210-215 operating temp was/is normal. On newer cars e-fans don’t kick on till 230-240...."

The higher thermostat temperatures are one way that automakers were able to reduce emissions to meet the ever tightening EPA regulations and this move was not done to increase horsepower. This is one reason why many ECM upgrades (for performance use) include a low temperature thermostat, like the 160° for many LS1 applications. Here in Central California, the 160°F thermostat is perfectly adequate and that is all we have ever used. We actually saw a HP reduction on the chassis dyno on one of our oval track cars when we elevated the coolant temperature, so we never went back.

Someone mentioned earlier in this thread that the cooling system is a combination and they hit the nail right on the head.

When I run a Robertshaw 160°F thermostat and 7 blade, 17" Lincoln Flex Fan on my 1975 Formula, I cannot get my coolant temperatures to go over 185°F even in traffic on a 100°F day. However, when I ran a AC-Delco Severe Duty Clutch and 7 blade fan, the car ran 190°F going down the freeway and over 200°F in traffic. The fan clutch effectively regulated the coolant temperatures.

You could actually hear the clutch fan 'lock up' or apply a little over 200°F and then 'kick off' a little below 190°F.

I will post photos of the temperature gauges (verified by a SW mechanical and infra-red gun) on a +100°F day to this thread later and the difference is remarkable...Robert

[David Jones]

I have an usual Pontiac. If I run a 160 thermostat, it runs 160. Everywhere. 195? Same thing. I like a 180 in my car.

[Z Code 400]

Here are the photos:

Photo #1:

+100°F day 75 mph with 7 blade fan and AC-Delco Severe Duty Clutch

(I also tried a Hayden Severe Duty Fan Clutch and it also kept temps up around 200°F all the time.)

Photo #2:

+100°F day 75 mph with 7 blade Lincoln flex fan

(The car will not ever get any hotter than this, even in traffic, verified by mechanical guage and ray gun.)


Note reduction in oil pressure in photo #2....Robert

[70GS455]

With adequate cooling sytem capacity, a good operating temp is one that is within a few degrees of the thermostat rating...

[J_JAMNIK]

[QUOTE=Region Warrior;3809802]All pontiac V8's used 195 stat's since 66.
210-215 operating temp was/is normal.

Wow, what a laundry list! Thermostats dont change NORMAL engine operating temps. Thats why when you install a 180 thermostat. The temp sooner or later approaches 200-210. The exception to this is a car that runs a certain temp without a thermostat. As to 210 being too hot, that is normal. For the transmission 210 is hot, thats why they have a cooler installed in the radiator on the return side. You may have serious problems if 210 is the temp of the coolant entering the water pump. Also ask yourself this: if 210 is too hot, why is it in the middle of most guages in mid 60's to late 70's Poncho's? Just my two cents!

[SRR]

Thermostats set the MINIMUM operating temp nothing more nothing less.

[71 T/A]

Originally Posted by Z Code 400

Here are the photos:

Photo #1:

+100°F day 75 mph with 7 blade fan and AC-Delco Severe Duty Clutch

(I also tried a Hayden Severe Duty Fan Clutch and it also kept temps up around 200°F all the time.)

Photo #2:

+100°F day 75 mph with 7 blade Lincoln flex fan

(The car will not ever get any hotter than this, even in traffic, verified by mechanical guage and ray gun.)


Note reduction in oil pressure in photo #2....Robert

Not to rain on your parade, but that's no big deal because you're not running a/c. I run a non thermal clutch in my 72 Formula with a/c. Without the air on, the car will run 170. With the air on and in traffic, it'll get to 210.

[bonnevista]

Please don't take this the wrong way, if had a temp gauge on my car and it was constantly running at 210 or above, I'd be looking to bring the temp down too. But as my current ride, a '72 Grand Ville, has an idiot light, I run it in the middle of summer in heavy traffic with the A/C on brrrrr and don't give it a 2nd thought - the 'hot' light hasn't come on yet and I'm pretty sure it works.
On the other hand, when I had my '66 GTO with a tri-powered 455, even though it didn't over heat, I had my eye on the temp gauge constantly.

[BVR421]

What BonneVista said. Around here an idiot light is the way to go on the street. LOL