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Trips4me · 07-21-2004, 02:35 PM

Ok folks... I know there is a "cooling and heating" forum but it seems that most of that is related to later model engines using 11 bolt water pumps, etc.
What I want to know is how many of you guys/gals are running 389's that are modified, have or had cooling problems, and what you have done to correct the problem.
I see several posts about radiators, carbs heating up, etc so I thought it might be a good idea to steal George's idea (thanks George)

and use it to focus on our specific vehicles.
So, that said let me start this off and tell you about my problem.

Specifics: 1965 389 + .060, 1965 #76 heads recently reworked with new stock valves, Crower springs, Comp Magnum 1.5 Roller Rockers, ARP studs w/ Crane Kool Nuts. Comp Ratio is about 9.65:1. I am running a SpeedPro 1175 cam (224/234, 465/488, 112 LSA) installed 4 degrees advanced, a '65 Tri-Power w/ 70-63-70 jets, Pypes RA manifolds into 2.5" Pypes, Goerlich mufflers, MSD 6AL, stock distributer w/ Pertonix Ignitor II and Flamethrower coil, Accell cap/rotor and Bosch wires and plugs. The rotating assembly is stock with cast pistons. The engine has about 1200 miles on it with about a dozen 1/8 mile passes.
I am running a stock radiator, 160 t-stat, new fan clutch and stock fan, rebuilt pump w/ cast impellor and I have modified the divider plates per Georges instruction.

The engine runs great but after reworking and installing the heads last week the engine is now running 10-25 degrees hotter that before. I did the divider mod and went from a 180 to 160 t-stat and it did not help much (maybe 5 degrees lower on the high end). I also backed off my timing from 12 initial to 10 which did not help. Anyone else running a similar setup and run into cooling problems..... Is it possible that I have overpowered the stock cooling system with the latest mods???? The underhood temps seem very high as well.. the carbs are hot as well as everything else. Let the games begin....

....Jim

Trips4me · 07-21-2004, 02:35 PM

Ok folks... I know there is a "cooling and heating" forum but it seems that most of that is related to later model engines using 11 bolt water pumps, etc.
What I want to know is how many of you guys/gals are running 389's that are modified, have or had cooling problems, and what you have done to correct the problem.
I see several posts about radiators, carbs heating up, etc so I thought it might be a good idea to steal George's idea (thanks George)

and use it to focus on our specific vehicles.
So, that said let me start this off and tell you about my problem.

Specifics: 1965 389 + .060, 1965 #76 heads recently reworked with new stock valves, Crower springs, Comp Magnum 1.5 Roller Rockers, ARP studs w/ Crane Kool Nuts. Comp Ratio is about 9.65:1. I am running a SpeedPro 1175 cam (224/234, 465/488, 112 LSA) installed 4 degrees advanced, a '65 Tri-Power w/ 70-63-70 jets, Pypes RA manifolds into 2.5" Pypes, Goerlich mufflers, MSD 6AL, stock distributer w/ Pertonix Ignitor II and Flamethrower coil, Accell cap/rotor and Bosch wires and plugs. The rotating assembly is stock with cast pistons. The engine has about 1200 miles on it with about a dozen 1/8 mile passes.
I am running a stock radiator, 160 t-stat, new fan clutch and stock fan, rebuilt pump w/ cast impellor and I have modified the divider plates per Georges instruction.

The engine runs great but after reworking and installing the heads last week the engine is now running 10-25 degrees hotter that before. I did the divider mod and went from a 180 to 160 t-stat and it did not help much (maybe 5 degrees lower on the high end). I also backed off my timing from 12 initial to 10 which did not help. Anyone else running a similar setup and run into cooling problems..... Is it possible that I have overpowered the stock cooling system with the latest mods???? The underhood temps seem very high as well.. the carbs are hot as well as everything else. Let the games begin....

....Jim

BOB VIDAN · 07-21-2004, 06:36 PM

Do you have the right cast impeller?

lil64gto · 07-21-2004, 07:54 PM

Jim

When you say a stock radiator, is it a 3 core or a 4 core? Is it the original or is it a newer one? Why .060 over on a thin wall block that ran hot out of the factory? Did you have this problem before the boring?

GTOLOVER · 07-22-2004, 05:06 AM

I have had problems with my 1965 GTO " appear" to everheat also. I cannot tell for sure because I have been having a problem with my temperature guage. In either case it gets really hot under the hood and the tri-power carbs get really hot.

I checked last night =and the radiator is in excellant condition and I also flushed the same just to be sure and it was really clean. I installed one of the Prestone flush tees and backflushed the engine and radiator. One thing I noticed is that the water exiting the radiator did not seem to be that great of a volume?

My first step is to try and fix the temp. guage. However, the radiator is only a 3 row radiator and I have a manual transmission. Even though it is in excellant condition should I increase to a 4 row regardless for this size engine?

Also , why does timing impact the temperature that an engine operates at? I have seen many comments on this and was wondering how much timing impacts the engine temperature?

Finally should the shroud enclose the fan? Mine appears to have been cut and there is a gap between the fan and the shroud? I have a seven blade fan.

Thank you
Dave

Trips4me · 07-22-2004, 05:11 AM

Bob... not sure what you mean by the "right" cast impellor??? It's the same pump that was on it before the head work.

lil64...The radiator is of unknown age but it appears to be a fairly new 4 core. I back flushed it when I did the divider plate mod and got hardly anything out of it. It appears to be in excellent shape and it flowed pretty well. As far as the block goes I have had this particular engine in the car since last September (the car had '67 326 in it when I bought it last year). I have run it on the dyno and the track and it has never overheated until I reworked the heads and installed the Rhoads lifters last week.

Trips4me · 07-22-2004, 08:19 AM

Ok.. After thinking about it and doing some further testing I've come to the conclusion that the engine is overpowering the stock cooling system. I ordered a Rodney Red radiator today and it should be here in about 3-4 weeks. In the meantime I am going to buy some more 105 octane (I usually keep 10 gallons but I've been out for awhile now) and do the mix to see if that helps. I think part of the problem is the 93 octane (hence the timing change) so if the higher octane fuel brings the temp down a bit and I install the RR rad it should be fine. Anyone have any thoughts on this?

mike nixon · 07-22-2004, 08:45 PM

moving this to the heating /cooling forum.

mike

BOB VIDAN · 07-22-2004, 10:21 PM

64-5 impellers had about 3/4 to 1 inch vanes and were fairly straight. 66-7 had much longer vanes that were swirled/curved.

Trips4me · 07-23-2004, 06:00 AM

Bob, I have the longer/curved vanes... so, what's the difference?

Rodney Red · 07-23-2004, 08:29 AM

I personally think that if a three row will not cool the car, you need to go aluminum. It seems that after 3 rows the airflow becomes restricted and there is little gain. But cooling is fickle, so sometimes it is just enough to work. How ever, I have replaced hundreds of 4 rows that didn't work and often made the problem worse.
Get a new fan shroud. The fan should be about 50/50 into it and about 1" of clerance around the edges. It should also be reasonablly sealed around the radiator

Trips4me · 07-23-2004, 08:43 AM

Hi, Jerry... is my radiator ready yet???

Just kidding...LOL!! Looking forward to getting it... BTW - I mixed the fuel and took it out for a drive last night.. it was only about 90 degrees outside and it was at 210 when I got home... stayed about 195-200 running 45-50 but as soon as I slowed down it started heating up. Jim

GTOLOVER · 07-23-2004, 10:08 AM

Rodney Red:
Thank you I will get a new shroud and I will try to check water pump. The next step will be one of you radiators.
Dave

Rick Rosen · 07-23-2004, 10:53 AM

I was having major over-heating problems...So
1. Replaced fan clutch
2. Installed fan shroud
3. Replaced temp sensor
4. Replaced 180 thermostate with new 108 thermostat
5. Replaced radiator cap...old one wasn't holding pressure

of course I did these one at a time...

I have a 4 core radiator...

Now she runs at 180 all day in town driving. Freeway driving is another story...it ranges depending on outside temp from 190 to 210...never any higher

If it goes any higher....I think it's time for a Rodney Red

GTOLOVER · 07-23-2004, 12:28 PM

Thank you very much!
Dave

BOB VIDAN · 07-23-2004, 07:15 PM

The long, curved impeller moves the water through the cooling system to fast, not allowing the water to cool. I have run the small vane impeller on all my 64 and 65's for almost 25 years and have never had a overheating issue. I know upgrading the motor could add additional heat to the cooling system, but I have added bigger cams, very minor porting and RA3 cast exhaust manifolds and still not had a problem.

buwalda · 07-25-2004, 04:13 AM

Trips,
www.stewartcomponents.com is about the best website for cooling info. [Howard Stewart bulit his own water pump dyno & testing facility about 12-15 years back & did all the research into cooling.]They have a Tech Tips section that firmly DEBUNKS the 'water travels too fast theory' along with alot of other old wives tails such as 'double & triple pass' radiators. FlowKooler have a 10 blade [new] impeller for s/b Chebbies to help with cooling UPTO 3000 rpm. Both Stew/Com & Davies Craig make inline electric booster pumps to boost low speed flow. All these things point to one thing: the water needs more flow, not less. If less flow was good, why do race engines with mechanical water pumps turn them at 5000 rpm & not 1500 rpm? I think you will find a 1 to 1.5" smaller water pump pulley will noticably improve your cooling; I realise these can be hard to find with the correct offset, but it is worth the effort. Every V8 I have owned [ many ] has benefited from a smaller pump pulley.

wheelspin · 07-25-2004, 04:46 PM

Jim,

Take a look @ my second post on 7/24 on the lengthy cast impeller thread. I think we are forced to "overcool" old clogged parts.

Les

Tom Vaught · 07-25-2004, 05:49 PM

The 64 and 65 GTOs suffer from the cooling going through the radiator too fast only due to the fact that the radiator inlet and the radiator outlet are on the same side.

In 1966 Pontiac moved the inlet to the driver's side for an improvement in cooling.

I have swapped the inlet to the other side on my
original radiator, found it cooled much better and when I had a custom radiator made had it build the same way (1966 style).

I have talked to stewart many times and he says you cannot put enough water through the block for cooling. If the engine does not cool properly it is the fault of the radiator or water pump speed, not the engines ability to use a lot of cooling water.

People should buy the book "How to cool your Pontiac" It is a great book and clears up a lot of the myths.

Tom V.

Trips4me · 07-26-2004, 11:19 AM

Tom.. .Jerry mentioned the inlet/outlet problem on the '65 radiator when I ordered my replacement. What outlet hose did you use and how did you clear the alternator. DO you have a photo??

Les... I agree that clogged passages may be a problem. That's one of the reasons that I am going to the RR rad... seems a better way to go than a rebuilt radiator. I did look at my heads when I got them back and they seemed pretty clean to me... I did not notice any rust, etc in them so hopefully it is as good as it gets there.

Bob, that is very interesting info on the pump impellor blades.. I was not aware that there was a difference. Thanks for sharing that with me... BTW - how do you go about getting a "correct" pump?

Geoff, good info.. thanks. I've thought about the pulley issue and have not discounted it yet. I'm pretty sure the RR rad will fix my problem but if not then a "correct" pump and a smaller pulley will be next on the list.

Great input from all of you... thanks again.

Jim

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