incredibly hot engine bay temps, need advice or suggestions 41 Willys 350, pics insid

I seem to be posting quite frequent here about issues here and there, Im working through one issue at a time. The truck is in great running order now so it's time to pick off the little things over the winter. The first is this hot engine bay.

Since downsizing the carb to a properly sized 600 the truck is running much more efficient. Since im using less fuel im noticing that the truck tends to run a little warmer even on cool days, such as now when we are seeing temps in the upper 30's. It seems to be running in the coolant temp range that it did over the summer in the upper 90's,and these temps creep up seemingly quick than they used to. This concerns me as it will get warm here again.

Im running a smaller radiator and electric fan in the front (due to the small size of the Willys grille), and a large radiator with dual fans pulling in the back so I should have plenty of radiator surface.

radiator in the bed:
http://i22.photobucket.com/albums/b3...0B2390BE27.jpg
and engine up front:
http://i22.photobucket.com/albums/b3...0A92657C53.jpg
This engine bay gets so hot that when I park the truck I prop the hood just to vent the heat. It feels like summer under there, its just trapping heat and it is going nowhere.

So Ive evaluated a few options:

1. Im running hooker headers, I know that I could wrap them to keep the heat in the pipes. However they are so tightly wound this would not be easily done and with the configuration of the headers in there it doesnt seem that the heat tape would be all that effective.

2. I could take off the panels on the inner fender wells (maybe the best option?) but this takes away from the clean look of the engine bay

3. I read that running an oil cooler can help drastically but with the cooler temps here in the fall and winter im worried about the engine not getting enough heat, and then im stuck with the oil sludging up.

4. Maybe the willys people will know this.... maybe there is some effective way to vent these hoods without making a drastic cosmetic change?

2 thoughts popped out at me.
First 1. where does the rear radiator draw air from? It looks like the cover encloses everything.
Second 1., How about adding louvers to the inner fender panels to allow the air to flow through?

Just had another 1.. have the headers ceramic coated by Jet Hot!

I agree with what 34_40 said. Can you have a radiator up front that lays similar to a corvette radiator did in the 63-80 style cars? I've had guys tell me that electric fans also help pull air in the engine bay and move the hot air out of the engine bay as well as help cooling the engine. Maybe you can place some small electric fans and help push air back and under the truck?

Since the problem started with the carb change, have you perhaps connected your vacuum advance to the timed port (above throttle port) on the carb instead of the manifold (below throttle port)?

Interesting info here on this and how it effects idle and low speed motor temps;manifold vacuum versus ported vacuum

The front radiator draws air from the grille in the nose cone, you can see the grille here
http://i22.photobucket.com/albums/b3...0AB97FD0D6.jpg
The radiator in the back is frenched and is open underneath so it draws the cool air from underneath the truck.

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Originally Posted by 36 sedan

Since the problem started with the carb change, have you perhaps connected your vacuum advance to the timed port (above throttle port) on the carb instead of the manifold (below throttle port)?

Interesting info here on this and how it effects idle and low speed motor temps;manifold vacuum versus ported vacuum

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Now this is interesting, I didnt tune the carb in or time it as I had a shop take care of that. They capped the timed port on the carb and removed the vacuum advance line off the distributor. The timing is set at 36 degrees, when I asked them about it they said that it did not need to be hooked up. However its having some cool starting issues so it is going back to them and they said that they will hook it back up and re-time it.

That read is interesting, that guy is running the same carb as me minus the electric choke. Ive been told not to run manifold vacuum though, I have a electronic Mallory ignition if it matters.

As I read there it seems like they are recomending manifold vacuum...interesting. So as I understand it and correct me if im wrong, the engine is running leaner at idle which of course makes things warmer inside naturally. So with ported vacuum advance from the carb its basically not adding spark timing therefore running warm, where as with manifold vacuum its adding spark timing in at idle.

The timed port is to meet some of the smog requirements, makes the motor run hotter to burn up the NOX. Not necessary on our hot rods, use the manifold port

Changing it made a big difference on mine, runs better and cooler!

Attachment 56681

Very interesting. Do the holley carbs work the same way with the ports as well?

Yes

Attachment 56682

Yea I'll give this a shot

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Originally Posted by 1923tbucket

http://i22.photobucket.com/albums/b3...0AB97FD0D6.jpg
The radiator in the back is frenched and is open underneath so it draws the cool air from underneath the truck.

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So if the air is coming in from the bottom, how does it get out if that cover comes down? :HMMM: :HMMM:

Good question I forgot to mention that. On the bed cover there are vents built into it. You can see them here in the middle of the to tonneau cover

http://i22.photobucket.com/albums/b3...0AB39FE10B.jpg

Curious if you've done any testing of temps going into and/or coming out of those radiators? An infrared thermal laser "gun" is really quite inexpensive and could answer some questions for you. Gauges have also been known to be inaccurate also.

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Originally Posted by 1923tbucket

Good question I forgot to mention that. On the bed cover there are vents built into it. You can see them here in the middle of the to tonneau cover.

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You say

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Since I'm using less fuel I'm noticing that the truck tends to run a little warmer even on cool days....

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which seems to say that it may not be different than it was before the carb change, but that you're noticing the operating temperature more now that you've got it running better?

Mike's right, some actual measured temperature data would help, but I think your problem is that tonneau. We can't see the details of the louver/vent cover, but from the picture it appears to have very small openings compared to the area. Without calculating the effective free area of your louver I'd bet that you're getting about 25% of the rated free air flow (CFM) of your fans, and maybe much less than that. In effect, it looks to me like you're bottling up the air beneath the tonneau cover, stifling air flow. The first thing I'd try is removing that black panel (if you can) and see what effect that has on your problem. If that solves it then your task is to come up with a louvered panel that has sufficient free area to move the volume of air your fans put out, with as little restriction as possible but still maintaining a "look" that you find acceptable, like maybe a sheet of aluminum or steel with rows of punched louvers. When you look at the rated flow of your fans and the necessary free area, you may find that you need to make that panel larger. Whatever you do don't add pusher fans to the pullers, or you'll further restrict the air flow even more.

I'm thinking a couple of fans could help. You can't get too much air flow at idle.

small front grill area also and then the grill bars restrict about half of that--------------Whole truck as an aero object--little air flow into the engine bay where the carb/engine burns up a lot of that, then using air for the rear that is already super heated from the engine /exhaust-------then trying to pull air thru that rear rad with those two little fans(do you know the amps for them?????) that aren't mounted so as to shroud the whole core area--------

Plus probably an A/C evaporator in front of the front rad??????

Common problem with fat fendered cars. Correct timing port might help a little, and Jet Hot (or similar) coating on the headers will help some but as 34-40 and others have mentioned you have got to get some ventilation under the hood!!! Can't get much air in there and then it has no place to exit the hot air! Louvers on the inner panels will help a lot, along with some sore of air pickup under the car at the front to get some air coming into the underhood area....

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Originally Posted by jerry clayton

small front grill area also and then the grill bars restrict about half of that--------------Whole truck as an aero object--little air flow into the engine bay where the carb/engine burns up a lot of that, then using air for the rear that is already super heated from the engine /exhaust-------then trying to pull air thru that rear rad with those two little fans(do you know the amps for them?????) that aren't mounted so as to shroud the whole core area--------

Plus probably an A/C evaporator in front of the front rad??????

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I see what your saying about the rear radiator fans not really covering the whole radiator, I should try and find or make a shroud for the rear radiator. The coolant temps arent horrible and over the summer they were manageable, I think most of my problem is in the engine bay with not venting the heat out however. I do have an A/C evap in the front as well yes, im going to have to come up with something to get air in and out of that engine bay.

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Originally Posted by rspears

You say which seems to say that it may not be different than it was before the carb change, but that you're noticing the operating temperature more now that you've got it running better?

Mike's right, some actual measured temperature data would help, but I think your problem is that tonneau. We can't see the details of the louver/vent cover, but from the picture it appears to have very small openings compared to the area. Without calculating the effective free area of your louver I'd bet that you're getting about 25% of the rated free air flow (CFM) of your fans, and maybe much less than that. In effect, it looks to me like you're bottling up the air beneath the tonneau cover, stifling air flow. The first thing I'd try is removing that black panel (if you can) and see what effect that has on your problem. If that solves it then your task is to come up with a louvered panel that has sufficient free area to move the volume of air your fans put out, with as little restriction as possible but still maintaining a "look" that you find acceptable, like maybe a sheet of aluminum or steel with rows of punched louvers. When you look at the rated flow of your fans and the necessary free area, you may find that you need to make that panel larger. Whatever you do don't add pusher fans to the pullers, or you'll further restrict the air flow even more.

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I havent done any kind of testing really as far as temps there, however i am looking to do something to promote some air flow into that engine bay for sure. AS far as the fans in the back im going to look into a shroud of some sort, they kick out some serious air.

Do you think something like this hid along the inside of the inner fenderwells pointing down towards the exhaust and forcing the air to exit would be a plausible idea?
http://www.summitracing.com/search/p...rd=air%20ducts

nope, not enough pickup area. Louvers are about the only thing that will allow sufficient air flow to do any good.

Yea im going to continue looking, I have a good idea of what I want to do I just need to find it. Im sure I can find or make a sheet metal duct that would bend slightly to vent air from under the truck up into the engine bay. Secondly at the hood hinge I can possibly space it somewhat and be able to vent it out up there. Im also going to get some underhood temps to see if what im doing is going to work.

Underhood temps are driven by your engine temperature, and while the air flow out of the engine compartment will affect the outcome it appears from what you say that most of your cooling is done in the rear radiator. Like Dave Severson says, punching louvers in your splash panels is about the only way to provide the air outlet you're looking for.

What coolant temps are we talking about here, and what thermostat are you running? Is your second radiator plumbed such that the thermostat controls the flow in that cooling loop, too, i.e. do you have the radiators running in series with no air trapped in the rear unit? Do you have an electric water pump, or are you trying to flow through that extra system volume with an engine driven OEM style pump?

Well my coolant temps have remained reasonable so far, but it is currently pretty cool out so its going to be hard to say what its going to do in the summer. My biggest thing is the underhood engine temps, the thing really hasnt overheated on me except for when the relay went out for the rear fans.

I had it out in some 100 degree temps with the ac on over the summer and it stayed around 200 (that was with a large carb and a rich mixture), the stat is a 160. My concern is driven by the hot underhood temps and the leaner burn im getting from a more efficient carb. I just really want to get that underhood temp down, im going to have to take some before hand temp readings.

I found some nice little fenderwell vents that im going to cut in around where the headers are, they look as if they will blend well too. Secondly ive come up with a design to promote some air flow from under the truck into the engine bay. Thirdly im going to space the hood near the windshield an inch to help vent the heat out there. Fourth im going to build a shroud make a better shroud for around the fan that is in the engine bay. Then we shall see what happens from there.

I could run hoodless too that would take care of it all.

Here is a source for round vents that you can put into the fender skirts with a hole saw;
Dive-N-Dog: Dive-N-Dog Vent-R-5 Stainless Steel 5 Inch Boat Engine Vent Cover

Just one question and I may have missed this Your radiator is in the rear area with a fan or fans> You have an A/C Evap in the front grill I assume.. Why can't you put a fan In the grill to pull air into the engine bay.

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Originally Posted by cffisher

Just one question and I may have missed this Your radiator is in the rear area with a fan or fans> You have an A/C Evap in the front grill I assume.. Why can't you put a fan In the grill to pull air into the engine bay.

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Yea I do have one on the front behind the grille so that helps too

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Originally Posted by 36 sedan

Here is a source for round vents that you can put into the fender skirts with a hole saw;
Dive-N-Dog: Dive-N-Dog Vent-R-5 Stainless Steel 5 Inch Boat Engine Vent Cover

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Yea there's a few I found that are even bigger than this yet that I'll probably be putting in.

Could always add louvers to the hood also...

If you're running a 160 t-stat and your coolant temps are pushing 200F cruising on a 100F day that points to an air flow problem. Shrouds are a must have, because without them you can just be blowing the same hot air through the radiator in a re-circulation pattern, but giving the fan discharge a free flow path is critical. If your cooling system is doing it's job the underhood temps will take care of themselves - you're not going to pick up much heat due to the air surrounding the engine if your coolant is circulating right, your radiators are sized right and clean, and your airflow is unrestricted. I still say your problem is bottled up air beneath the tonneau, and the easy test is to run without it to see if the engine stays nearer to the t-stat control point.

Hoodless would not look good on that HotRod, my two cents. Throwing out some things to evaluate, those rear fans could you install larger fans to give you more coverage of the radiator? Do the fans suck air from the bottom up, if so maybe consider reversing that air flow? How is the cooling route plumbed in, rear first cool and then front secondary ? Finally the inner finder wells will more then likely give the biggest bang for the buck, the boat air vent is a good idea. I would look around some to see what is out here that could vent larger areas

This link is for a visual reference of the idea, modify something like this to fit ;
Amazon.com: 30" x 10" RETURN GRILLE - Easy Air FLow - Flat Stamped Face: Home Improvement

Reading Rogers post sounds like the bed area is a sealed box type of deal and the air is vented out the cover. I would think that you would need access to the ambient air for the rear to give better cooling.

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Originally Posted by rspears

If you're running a 160 t-stat and your coolant temps are pushing 200F cruising on a 100F day that points to an air flow problem. Shrouds are a must have, because without them you can just be blowing the same hot air through the radiator in a re-circulation pattern, but giving the fan discharge a free flow path is critical. If your cooling system is doing it's job the underhood temps will take care of themselves - you're not going to pick up much heat due to the air surrounding the engine if your coolant is circulating right, your radiators are sized right and clean, and your airflow is unrestricted. I still say your problem is bottled up air beneath the tonneau, and the easy test is to run without it to see if the engine stays nearer to the t-stat control point.

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Yea that makes sense, looks like I have some work to do this winter. I never thought of it like that those fans just recirculating the air and not pulling as much makes sense.