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Discussion Starter #1
Seems my car has started somewhat overheating. By somewhat I mean its getting up in the 220 range and a slight spew out the overflow when I turn it off. It was running well for a while then this....I posted a earlier thread with no responses on my fan not being 1/2 way in the shroud but has since been remedied with the below solutions. The questions I have are as follows. 1) Do you do the block test looking for exhaust gases with the engine running but cold w/ the thermostat closed? 2) should the engine overheat and spew out the radiator with the cap off? I have changed the thermostat,water flow looks good, all plugs look the same,
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remedied the fan/shroud situation. Had the radiator/fan off so I backflushed the radiator with the hosed taped to the lower hose fitting. Nothing in the tune dept. has changed since it ran well. No positive in the block test. ????????
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Just a few quick questions, what is the model of your car, engine size etc

How are you measuring the temperature, (dash gage, heat gun etc)

Is this while idling, driving or both?

Is the over flow tank half full when cold?

This should further the discussion??
 

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Discussion Starter #4
I have the original 400 rebuilt about four to six months ago. Bore 30 over and compressing down to 9.6 at 5000 altitude. have measured with dakota digital gauges and temp gun. T he only reason I bring this up is because it' would run about fine at 200 on the gauge with no problems....its just recently started to hit 220+ and spew some out on the ground when I turn it off only. I dont have a overflow bottle. If I run it till the thermostat opens up without the cap then turn it off...should it spew out the top of the radiator when I turn it off? Is that normal?
 

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When you run without an overflow bottle if you fill up the radiator to the brim of the radiator cap when you shut it off it will expand and overflow out of the tube.

with no overflow bottle the level of coolant must be 1/2 to 1 inch below the top of Radiator.

from the picture that fan does not look half in the shroud, it looks to be beyond the shroud. Am Inseeing this wrong?...half I is half of the fan BLADE.

Engines instantly heat up when you turn them off, because no coolant is circulating.....

make sure the fan is half in and half out, check coolant level......220 after shutoff if it does not boil out is OK,....and long as it runs cool....
 

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Discussion Starter #6
When you run without an overflow bottle if you fill up the radiator to the brim of the radiator cap when you shut it off it will expand and overflow out of the tube.

with no overflow bottle the level of coolant must be 1/2 to 1 inch below the top of Radiator.

from the picture that fan does not look half in the shroud, it looks to be beyond the shroud. Am Inseeing this wrong?...half I is half of the fan BLADE.

Engines instantly heat up when you turn them off, because no coolant is circulating.....

make sure the fan is half in and half out, check coolant level......220 after shutoff if it does not boil out is OK,....and long as it runs cool....
The first picture is completely out of the shroud.... the last is after I spaced the shroud toward the engine. approx half...I think. Just checked my timing and it hasn't moved and dwell is 32. Yes I might have had it overfilled. I will take it for a spin tomorrow with the coolant slightly lower(y).
 

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You can also buy a fan clutch r

That has an inch longer neck, as long as you are not hitting the radiator....it will extend it into the shroud
 

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You do have a lot of air spaces around the shroud, the factory has that all sealed with rubber,...you can even buy the rubbber seal kits that go around the shroud from Ames...

that way the only air pulled is through the radiator
 

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Discussion Starter #11
You can also buy a fan clutch r

That has an inch longer neck, as long as you are not hitting the radiator....it will extend it into the shroud
Where can I get one. I did some searching but came up empty. I would prefer that to my method. I am not even certain my shroud is correct. What does yours look like? Are 66/67 the same?
 

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Ames sells the shrouds part number P151A or P152A,...they also have rubber surround Kits

Always buy a thermal fan clutch .....(double.Check because the non-thermal fans do not cool as good)

The original fan is like this from summit.......AC Delco 19189678......

The later year 350 engines had a bit longer shank AC Delco 19189681....

Don't take these parts as gospel do your own due diligence with the supplier on fit and measurements, this is not original to engine so you must measure the shank ask the techs at summit or ames. Also measure your clearance.

other makes of fan clutches Hayden, Four seasons may also have longer shanks, as I recall about 7/8 or 1 inch longer.

let us know how you do, fan BLADE should be half in and half out of a sealed up shroud for best cooling...
 

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Have you checked the clearance between the divider plate and the water pump impeller? If that's not right, then nothing else you try will work to keep it cool.

Bear
 

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Discussion Starter #14
Have you checked the clearance between the divider plate and the water pump impeller? If that's not right, then nothing else you try will work to keep it cool.

Bear
Ya I did when I rebuilt it, seem to be doing fine until lately. I ordered a new radiator cap also. (because I had a billet cap on my aluminum radiator)
 

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Dual flexilite 13” electric fans with shroud. Pulls 4,500+ cfm at idle. If you don’t care about being numbers matching or all original... thats the best way to keep temps down. The controller that comes with it will keep the fans on for 30sec after the car is turned off to help with the ambient heat soak.

Also for a cheap solution to bring coolant temps down, dump a bottle of Water Wetter in the coolant. It can bring the average temp down by 10-15degrees. I do this with every classic car/hotrod i work on.
 
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