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post #1 of 28 (permalink) Old 06-12-2019, 10:38 PM Thread Starter
 
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Still to HOT

My 66 with 389 runs hot . I have changed water pump ,fan clutch, lower hose to one with spring. Had radiator checked and flushed. Timing is OK .and have Dakota digital gauges and sending unit.
Engine seems to gradually keep warming ,it may drop 2 or 3 degrees then climb back more. cooler air helps, hot days are a no no. I was told that the function of a fan clutch was to release at higher road speeds to let the air taken in work and not be hindered by fan. So I have 3.55 gears- is my road speed not sufficient for engine RPM. Has anyone changed from fan clutch and fan to a flex fan and spacer so that engine speed would be higher in relation to road speed?
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post #2 of 28 (permalink) Old 06-13-2019, 02:46 AM
 
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Just a thought. Have you made sure your metal guide plates behind the water pump are as close to the impeller as they can be? I adjusted both my 389 and my 326 and it gave me a few degrees difference. Defiantly helped out here in the hot Arizona heat.

Jim
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post #3 of 28 (permalink) Old 06-13-2019, 07:27 AM
 
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I went back to the clutched fan setup (better).

What type of radiator are you using? What degree thermostat are you using and have you verified it is completely opening?

(I like to run a 180* thermostat and my car with an aluminum radiator will stay under 200* on the hottest days being raced. Driving normally, the car stays around 190*.)

What timing is the car set to base and total ?

What are is the approximate temperature coming into the radiator vs coming out (use a laser temperature gauge)?

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #4 of 28 (permalink) Old 06-13-2019, 10:11 AM Thread Starter
 
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How do you adjust dividers? I put in new stainless steel ones and the back one has a notch that fits tight against the housing.
I have tried 2 thermostats (160) and checked them in heating water both are OK. I am running original 4 core radiator made for a/c with bottom plugged because it now has 4 speed. Timing is 8 BTDC with advance
disconnected. That is the way the Mechanic set it up when he installed Pertronix Ign. I pull into driveway at 205 degrees and by the time I turn around and back it into shop it has hit as much as 230.
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post #5 of 28 (permalink) Old 06-13-2019, 06:41 PM
 
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Do you have appropriate fan shroud? ...........That will make it run hot If not shrouded right.

Also you need a thermostatic fan clutch, in good shape. they have RPM activated fan clutches that look very similar, but will make it run hot.

Even the thermostatic clutches wear out gradually, do you see black oil around the fan blades? Of on the front of the water pump? May be silicone leaking from the fan clutch. If it is bad it runs up temp at idle, since that is when it works.

When the car is cold it should barely spin by hand.....car off, goes without saying here.

8 degrees with advance disconnected,....when it is connected does it add timing? In other words is it connected to full manifold vacumn or ported vacumn? Full manifold vacumn will increase timing at idle and greatly improve idle cooling, if it is ported vacumn and 8 degrees only. It will run hotter than it should best cooling is near 20 or so, but you get the extra from vacumn advance.

Any drippage out the weep hole at the bottom of the water pump? Even new ones can leak. Some coolant leaks are hard to find. Here and you never notice them. Here is a good way to check. Get a radiator pressure tester from your auto parts or favorite vendor, or borrow one.

Start with a cold car. Put the pressure tester on the car. Start the car up and get it to normal temp, dont drive it, right in the driveway pull in

the garage or park it so it is clean and dry underneath. Now shut the car off and pump the pressure tester up to 16 PSI. Now go drink 4 beers , watch the game and go to bed. In the morning, go down and look under your car. If there is a leak in the coolant system, it will be evident. See if you can see where it dripped from and repair accordingly. If it gets hard to find, add some coolant dye, any auto parts store and repeat the test the next night. But this time have 5 beers, and when you get up get the black light and go check for the leak.

A temp gun will also help you diagnose it as well, I think cj said that, run the gun around the hoses and the radiator looking for hot and cold spots, may show you where there is a blockage or no flow.

If none of this works, you will have to move to Bourbon.
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post #6 of 28 (permalink) Old 06-13-2019, 06:47 PM
 
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Originally Posted by Datold1 View Post
How do you adjust dividers? I put in new stainless steel ones and the back one has a notch that fits tight against the housing.
I have tried 2 thermostats (160) and checked them in heating water both are OK. I am running original 4 core radiator made for a/c with bottom plugged because it now has 4 speed. Timing is 8 BTDC with advance
disconnected. That is the way the Mechanic set it up when he installed Pertronix Ign. I pull into driveway at 205 degrees and by the time I turn around and back it into shop it has hit as much as 230.
Get a new mechanic. The distributor advance not only can help in gas mileage, it can also help cool the engine.

I suspect you have factory high compression, 10.5:1? Pontiac engines like 10-12 Initial which may help. But, this may then change your total mechanical timing and the total timing with the vacuum advance hooked-up. So that means you will now have to address your distributor. Your total mechanical timing should be around 34 degrees, and possibly more (maybe 36) if you have the original closed chamber heads. But with high compression, you need racing gas or an octane additive or you will get engine "pinging" or detonation when you put a load on the engine.

I did not see that you listed a fan shroud? If you do not have one of these, get one.

So, you may want to refresh us on your engine build and what timing specs you do have - like total mechanical degrees @ "X" RPM.
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post #7 of 28 (permalink) Old 06-14-2019, 03:38 AM
 
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What stabilized my engine temps in the Arizona heat was to make sure the metal plates are as close to the impellers for max water flow. After I had everything else eliminated, I pulled the water pump to see how close the impellers were to the metal plates. Both my 326 and the 389 had gaps with the 389 being quit significant. I wish now I would have recorded the distance. For the 326 I was able to tap the metal plates with a mallet to reform them to narrow the gap, within approximately a 1/16 of an inch. I gained as much as 10 degrees cooler and noticed the gauge is more stable as I drive around.

The 389 is newly rebuilt. While I was breaking in the cam, I had to shut down as the engine was trying to overheat. The gap on these plates was a good of an inch so I was unable to mallet them into position without distorting the plates. My fix was to add the shim you see in the photos and reworked the plate which took up the gap and still allows the coolant to flow. I was able to complete the break in and Ive ran it several times with no issues although it has not been road tested yet. The shim I made from 7075-T6 aircraft aluminum .160 thick as that is what I had on had at the time. I then bonded and used aircraft rivets to secure it to the plates.

With aftermarket water pumps, who knows how far they press the impellers on when they are manufactured. I have four pumps to compare to and all were slightly different with both cast and stamped sheet metal blade impellers. By having the larger gap in allows the coolant to cavitate, closing the gap forces the coolant though the system. It is a known issue and with a bit of searching on line youll find discussions about this particular problem. With everyday Arizona summer temps of 110F you do everything you can do to keep your engine in check.

Jim
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post #8 of 28 (permalink) Old 06-14-2019, 06:48 AM
 
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OK a lot of great feedback so far and I'll chime in too:

(1) Timing is incorrect and without a doubt is adding to your problem. Before connecting vacuum to the distributor , check total timing (should be ~36*). If total is not at 36*, set timing so that it is (ideally coming in by 3000 rpm. Then check base / initial timing and record. Then connect the distributor advance can to vacuum and check what your timing jumps to at idle (most likely will run much better immediately) .

(2) Get a great Aluminum radiator

(3) If you're mechanic removed timing because your compression is too high, then either run race gas or lower compression properly....(get a new mechanic)
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1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #9 of 28 (permalink) Old 06-14-2019, 01:05 PM Thread Starter
 
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I have the correct fan shroud -according to Ames book. I haven't lost any noticeable coolant . I have not seen it boil out. I put a heat gun on it yesterday- it closely corresponded to Dakota gauge at the sending unit
At 180degrees the head were at 375-400 the front freeze plug on rt. head was nearly 500. water flows well. I am going to hook vacuum advance back up. I put on a new fan clutch it made no noticeable difference
The engine was fresh when I bought the and the paint was good. The heads were supposed to be done but were not so the shop drilled and installed 7/16th studs, new guides, vales, valve seats balls locks etc. they did state they took .010 off. It is bored .030 over compression is at 180. I am beginning to wonder if the shop is not looking to sell me Edelbrock hrads or some other work. Thanks Guys
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post #10 of 28 (permalink) Old 06-14-2019, 05:28 PM
 
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I have the correct fan shroud -according to Ames book. I haven't lost any noticeable coolant . I have not seen it boil out. I put a heat gun on it yesterday- it closely corresponded to Dakota gauge at the sending unit
At 180degrees the head were at 375-400 the front freeze plug on rt. head was nearly 500. water flows well. I am going to hook vacuum advance back up. I put on a new fan clutch it made no noticeable difference
The engine was fresh when I bought the and the paint was good. The heads were supposed to be done but were not so the shop drilled and installed 7/16th studs, new guides, vales, valve seats balls locks etc. they did state they took .010 off. It is bored .030 over compression is at 180. I am beginning to wonder if the shop is not looking to sell me Edelbrock hrads or some other work. Thanks Guys

Shooting the laser gun at the heads really doesn't give much info. It is the radiator you want to check. Mainly, the difference between the top and bottom to see how well the radiator is actually cooling.

How about a photo of the fan blades-to-shroud? It the fan is too far away from the shroud, it won't pull air like it should. The clutch fan used on A/C cars has a 7 blade fan that is 19 1/2" diameter. The clutch fan could be ordered on most V8 cars as an option - if this is what you have.

With 180 cranking pressure, you should have 10.5 or possibly slightly more compression. Again, assume you are running race gas/high octane or an octane booster. You probably need about 100 octane at that compression. Higher octane will not detonate like pump 91 or 93 octane and you can then adjust your timing up which may aid in cooling.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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