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Old 05-01-2013, 05:02 PM
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350 Small Block Heat Issues in a Jeepster

This is my first post here since this is not my car but my father in laws. Though I do work on the wifes Defender 90 3.9L V8 quite a bit, I have not had a chance to work on a Chevy V8... yet!

So the story with this goes that he got this Jeepster in good body condition with a shot engine. Had a guy swap it out for a small block 350 V8 a decade ago and has had never ending heat issues since. It will creep up to 250 degrees easy though has never blown it's top. Every year FIL plans his summer road trips in the Jeepster and every year thrown money at the cooling system hoping that a new this or that will fix the heat issue. His thoughts are a combination of too small a radiator for too big an engine, too small an opening in the grill for air to pass through, and etc. Though the science of sizing a radiator to an engine seems to be more trial and error? The radiator in there now is as big a unit as will fit.

What he has is a 24" wide x 16" tall x 2" thick 2 coil aluminum radiator. A shroud made of sheet aluminum right against the radiator with 2 puller fans. The sheet shroud covers the whole radiator with holes cut for the 2 fans. In my thinking it seems this shroud plate actually blocks air rather than directs it to the fans with it being mounted right flat to the radiator? The fans also seem a little cheap to me but I've not yet looked into what fan options are out there so if there is a better setup please let me know. This may be a to shroud or not to shroud situation and am sure there are many thoughts on whats' best.

One of the fixes he is considering is replacing the water pump with a high flow type. Though if the radiator isn't doing it's job I'm not so sure that will solve anything?

His very last resort is to swap the engine back to a stock 6 because he will drive this car till he dies as he claims. But the 350 has such a great sound and feel that I think that would be a shame.

The link below is to an album of the car and engine from the other night. Sorry they may be a little dark but I'm hoping someone here may be able to give some suggestions of a fix.

Thanks,

Karl

https://plus.google.com/photos/10256...CJ--1sfX-uWvZA

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Old 05-01-2013, 05:22 PM
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I have some questions, we'll need more info. Is the motor stock? Compression rstio? Timing? All those issues could raise temp. What thermostat 180? Did you try another gauge? Does it overheat? I mean does it boil the water out? running down the road or in the drive way.? Some of those pumps were meant to turn the other direction.
Where does that heater hose on the intake come from? if it comes from the pump, I would disconnect and plug it both sides. If it doesn't get hot in the drive way, with the hood up, I would take the condenser out and try it, that rad looks small and maybe not enough air flow.
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Old 05-01-2013, 09:36 PM
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I am in process of putting a 400 SBC in a Jeep Wrangler and have looked at a lot of radiator set ups trying to decide what to use.

Core size recommendations are approximately 22x26 typically and electric fans with a shroud are normally recommended. However, I think there needs to be clearance between the fan side of the radiator and the shroud to avoid blocking off cooling capacity.

Temperature gages are notorious for providing bad numbers so checking the temperature with an infrared heat gun is a good way to confirm what the gage is reporting.
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Old 05-08-2013, 02:44 PM
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I know my first post was missing way too many variables in the equation! What has been figured is that the builder that originally installed the V8 claims that you need 1 cu in of radiator per horse power. With that figure the current radiator is about 300 cu in and the horsepower somewhere about the same or a little more. What he has done is gone ahead and ordered up a custom 4 core radiator that will be in the 600 cu in size. I'll let you all know if that fixes it.

Thanks for the replies,

Karl
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Old 05-08-2013, 04:55 PM
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Quote:
Originally Posted by swede7000 View Post
This is my first post here since this is not my car but my father in laws. Though I do work on the wifes Defender 90 3.9L V8 quite a bit, I have not had a chance to work on a Chevy V8... yet!

So the story with this goes that he got this Jeepster in good body condition with a shot engine. Had a guy swap it out for a small block 350 V8 a decade ago and has had never ending heat issues since. It will creep up to 250 degrees easy though has never blown it's top. Every year FIL plans his summer road trips in the Jeepster and every year thrown money at the cooling system hoping that a new this or that will fix the heat issue. His thoughts are a combination of too small a radiator for too big an engine, too small an opening in the grill for air to pass through, and etc. Though the science of sizing a radiator to an engine seems to be more trial and error? The radiator in there now is as big a unit as will fit.

What he has is a 24" wide x 16" tall x 2" thick 2 coil aluminum radiator. A shroud made of sheet aluminum right against the radiator with 2 puller fans. The sheet shroud covers the whole radiator with holes cut for the 2 fans. In my thinking it seems this shroud plate actually blocks air rather than directs it to the fans with it being mounted right flat to the radiator? The fans also seem a little cheap to me but I've not yet looked into what fan options are out there so if there is a better setup please let me know. This may be a to shroud or not to shroud situation and am sure there are many thoughts on whats' best.

One of the fixes he is considering is replacing the water pump with a high flow type. Though if the radiator isn't doing it's job I'm not so sure that will solve anything?

His very last resort is to swap the engine back to a stock 6 because he will drive this car till he dies as he claims. But the 350 has such a great sound and feel that I think that would be a shame.

The link below is to an album of the car and engine from the other night. Sorry they may be a little dark but I'm hoping someone here may be able to give some suggestions of a fix.

Thanks,

Karl

https://plus.google.com/photos/10256...CJ--1sfX-uWvZA
Nice looking installation but wow is it out of space. Looks like an AC condenser ahead of the radiator, nothing like a little preheated air.

More water pump flow isn't the problem there just isn't any way to get air through the radiator core with the fans right up against it.

The small block 350 with a 2 row 1 inch tube aluminum radiator needs a core of17 by 26 inches with tanks that would be about 31x19. My experience shows a 2 row of 1 inch tubes of this size cools the same as a 3 row brass unit of the same dimensions.

The idea of a shroud is to enclose the perimiter of the radiator with the fans located a distance behind such that when they run, they pull an air flow across the entire core. With just fans the air is mostly from in front of the fan. However, at cruise speeds from about 25 mph up there should be enough air flow to cool the engine without the fans running. Any shroud needs to stand proud of the core at least an inch, more if you can get it too allow flow space for the air to enter over the entire core then bend and move to the fans for exit. The term "plated" makes me think there is no gap between the "shroud" and core which will not allow air flow from the closed off section, it might run cooler without this. I'd take advantage of as much space as you can get in designing a shroud. It would probably have to enclose some of the fan's depth inside the shroud given how they are located in relation to the core. This will be tough to shape in metal unless your a pretty good metal worker.

An oil cooler can be a helpful adjunct to the radiator if you can find space for it away from the radiator and condenser. A model with a built in fan would be good. These can take about 10-20 degrees off the coolant temperature by dropping the amount of heat the oil transfers into the cooling system by conduction through the casting structure.

Replacing the chrome rocker covers with unpolished cast aluminum can be worth a few degrees, polished or chromed surfaces are poor at transfering heat. This won't be much but it looks like this can use every trick available.

Water wetter is useful in that its detergent action breaks the surface tension of the water in the coolant allowing it to hug the surfaces tighter which transfers more heat. I don't usually see the temperature reduction claimed but the thermal saturation of the coolant appears better, this picks up more heat but also delivers more heat into the radiator tubes, so things look like not much is happening when in fact the total amount of BTUs in the flow is increased. An oversized radiator would probably show a temp drop with stuff where the larger surface area would allow more heat flow out of the coolant. Otherwise the advantage appears to be that water wetter helps surpress local boiling inside the cooling jackets which is an important protection for exhaust valves and seats, and spark plugs.

We've also had installations where an auxillary radiator had to be installed somewhere along the bottom of the vehicle or pipe secured to the frame to increase both liquid volume and heat transfer surface by using the frame as a heat sink.

But in this case, my first attention would go to the shroud and fan installation.

Bogie
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