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Discussion Starter · #1 ·
Hi Everyone,
My 64 with 327/air/auto is running hot. If I sit at a light too long my temp goes all the way to 205 degrees and never comes back down. The car has always run at about 190. I have checked everything. I noticed that the temp difference between the input and output of the radiator is only about 15 degrees. Shouldn't the radiator be cooling much more than that, like 40 degree difference? Just not sure what to do besides buy a new radiator. Any comments are appreciated.

Thanks.
 

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Because a 50/50 mix of coolant/water, at about 15 psi, boils at approx 265F. And the GM 'idiot' light does not begin to glow until about 235F, I would not be too concerned about 205F. BUT, 'normal' temps should return upon resuming forward movement (after they rise at idle).

Because it is rising at idle, it would more likely be the air flow thru the radiator at idle (provided by the fan). Fan belt? Fan positioned improperly in the shroud? Wrong fan?

The thermostat not be opening fully, or at the proper temp?

The OEM GM configuration for the 327 w/air was a clutched 17 1/2" (approx diameter), 5 blade non-symmetrical steel fan. A malfunction of the clutch?

Or, you may have some malfunction/mis-application of an after market configuration.

You stated you checked everything so I'll skip the 'low coolant', 'collapsed hoses', type options.

Pete
 

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Discussion Starter · #3 ·
Thanks Pete. Yes I have checked everything. New thermostat, coolant and fan clutch. When the car is running and the radiator cap is off, I can see the antifreeze flowing by at a good clip so the flow seems to be fine. I tested a piece of paper near the front of the radiator and it gets sucked in so air flow seems good. I am just at my wits end on this one and looking for someone to suggest something I may have overlooked before I spend $700 on a new radiator.
 

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Discussion Starter · #5 ·
Sorry, should have included this part: was tired of my old Rochester 4GC carb that always gave me trouble so I replaced it with an Edelbrock 1406. That's when it seemed to start running hotter. Could that be a coincidence? Checked the timing last week and I'm running at about 7 degrees advance. Pulled spark plugs and definitely not running lean. I'm in PA and ambient temp is like 70 right now so I'm guessing the car might not be drive able once the summer heat starts.

Matt
 

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Discussion Starter · #7 ·
I guess it's possible. I could try replacing with another since that is cheap but I have seen the coolant flow right as the thermostat opens up.
 

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Thanks Pete. Yes I have checked everything. New thermostat, coolant and fan clutch. When the car is running and the radiator cap is off, I can see the antifreeze flowing by at a good clip so the flow seems to be fine. I tested a piece of paper near the front of the radiator and it gets sucked in so air flow seems good. I am just at my wits end on this one and looking for someone to suggest something I may have overlooked before I spend $700 on a new radiator.

The 'new' fan clutches (a la Hayden, for example) come in differing specs/'duty'. Perhaps re-installing the old one (just to see what happens) may yield some useful info. It may be better suited to your engine.

The 'clutched' fan does not improve cooling. It de-clutches when 'cooling' in not needed to allow the torque used to rotate it to be used elsewhere (propulsion). But, not using the 'correct' one (for your application) could (emphasis on 'could') produce the minor changes you are seeing.

Try advancing your initial timing to around 10 degrees BTDC. You're a little 'retarded' (the timing, not 'you'). If you see some improvement in the temp (and are not getting any 'pinging'), try 12.

When you changed the carb, did you connect the vacuum advance to the 'manifold vacuum' port? NOT the 'timed vacuum' port!

Here's a little reading (if you do not already know this stuff):


Ever notice that fan belts come in differing 'V's? The incorrect belt may slip in the pulley 'grooves'.

The above are a few 'free' things to investigate. And 'yes', I've had thermostat be defective 'out of the box'. Yours is obviously 'opening' but does it start opening at the correct temp? Opening 'fully'?

Pete
 

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Hi Everyone,
My 64 with 327/air/auto is running hot. If I sit at a light too long my temp goes all the way to 205 degrees and never comes back down. The car has always run at about 190. I have checked everything. I noticed that the temp difference between the input and output of the radiator is only about 15 degrees. Shouldn't the radiator be cooling much more than that, like 40 degree difference? Just not sure what to do besides buy a new radiator. Any comments are appreciated.

Thanks.
Could be alot of things: Thermostat not opening (do not buy a lower rating if you have automatic transmission, stay with 195; test thermostat on stove. how old is radiator? Do not buy another rad, have your original re-cored. Water pump leaking? Fan shroud in place correctly? hoses not kinked? My procedure has been to make sure tthermostat is opening, look for water pump leak at weep hole, put cleaner in rad and back flush . if this fails and my rad is old like more than 5 years, I do a re-core. Did you use tap water on last radiator fill, That could be
a disaster and need re-core, use only distilled water or pre diluted brand. Just say'.
 

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Discussion Starter · #10 ·
Water pump is not leaking. Fan shroud is good, hoses are good. Radiator was re-cored when the problem first appeared but the problem still exists. Thermostate for sure is opening as I have witnessed the coolant flow. I used the pre-mix 50/50 coolant.

Why the need for a 195 thermostat if I have an automatic transmission?
 

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I recommend 190F for aluminum heads, 180F for cast iron. Cast iron 'holds' heat more than the aluminum. Both pretty much create the same crank case temp (to burn off crank case gases). It's not a big deal which thermo is use in that range; they are mostly interchangeable.

Autotrans/ thermostat 'connection'? I don't see one.

Because you stated the temperature rise began when you changed carbs, re-check the carb installation.

You never responded to the question about the vacuum advance. Your temps MAY be rising the small amount you are seeing because the vacuum advance is set up wrong. Use full manifold vacuum, NOT the timed vacuum. The 1406 gives you a choice.

Pete
 

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Discussion Starter · #12 ·
Thanks Pete for the additional info. I will double check the carb setup. I just looked at the picture and you are right, I think I am using timed vacuum and not manifold vacuum
 

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Discussion Starter · #13 ·
One other thought I had: if I do switch to manifold vacuum, won't that essentially make the car run even leaner? Could you explain why using manifold vacuum would be better?
 

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One other thought I had: if I do switch to manifold vacuum, won't that essentially make the car run even leaner? Could you explain why using manifold vacuum would be better?
It's explained very well in the link I provided on an earlier post. I recommend you read it.

Now, you may need to make some adjustments. After switching, you should see an increase in idle speed. Adjust it (800 rpm, or so).

Disconnect and plug the vacuum advance from the 'pot' at the distributor and check your timing. This is your 'initial' timing. I'd start with 10 degrees BTDC (refer to my earlier comments). Adjust it if necessary.

Re-connect the vacuum hose and check your timing. This is your timing with vacuum advance. Compare with the data provided in the link.

I'll let your read about mechanical advance. You likely don't need to futz with it. Knowing what it is may be helpful diagnosing future problems.

Optimizing the timing is a trial and error evolution. Set it, run/drive the car, re-set as necessary (until you find the 'sweet spot'). Timing is free to adjust and can be 'put back' to any setting.

The engine should run a little cooler (and better) if tuned/timed properly.

After the timing/ignition is correct, you may need/want to adjust the carb to optimize the mixture for the 'new' timing.

Pete
 

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63 imp. 283. PG. 321 rear
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Hi Everyone,
My 64 with 327/air/auto is running hot. If I sit at a light too long my temp goes all the way to 205 degrees and never comes back down. The car has always run at about 190. I have checked everything. I noticed that the temp difference between the input and output of the radiator is only about 15 degrees. Shouldn't the radiator be cooling much more than that, like 40 degree difference? Just not sure what to do besides buy a new radiator. Any comments are appreciated.

Thanks.
Check e z. First
have a fan shroud ?
Add an auxiliary electric fan
A e z adaptation trick
where hood meets Cowell remove rubber molding which slides through channel. Gives Unice air event
Don’t drive in rain because can drip down the firewall without rubber, juss say’ in.
 

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Discussion Starter · #18 ·
Pete - thanks so much for your insight and the link. I did not "see" the link because I thought it was an ad with the post. I read the article and still don't fully understand. I need someone to break it down and put it into terms for a simpleton like me who is still learning.

I did what you said. I connected the vacuum line to the manifold vacuum port, adjusted the timing and the idle mixture, drove the car and played with it a little bit more. The car ran at between 185 degrees and 192 degrees for 40 minutes after warm up.

I learned a little bit and hopefully can gain some more understanding.

-Matt
 

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Matt,

Glad the timing change helped.

"Fully' understanding all the physics and engineering in not necessary to tune a car for street driving. Understanding the three components (initial, initial w/vacuum advance, and mechanical/centrifugal) of an engine's timing is helpful.

Here's another link


Just info.

Pete
 
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