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

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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:

and engine up front:

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

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

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!

edlebrook vac.jpg

The front radiator draws air from the grille in the nose cone, you can see the grille here

The radiator in the back is frenched and is open underneath so it draws the cool air from underneath the truck.

Originally Posted by 1923tbucket

The radiator in the back is frenched and is open underneath so it draws the cool air from underneath the truck.

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

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

Yes

holley vac.jpg

Yea I'll give this a shot

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

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.

You say

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

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.

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.

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.

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.