55.2-59 cowl vent

[lynx5653]

Can engine heat somehow be directed to the cowl vent on 55-59 trucks? Running a 454 and need to get rid of heat without putting vents in hood

[mongocanfly]

With alot of mods it could....but the cowl vent feeds air into the cab

[MiraclePieCo]

Wouldn't a reverse hood scoop be easier and better way of siphoning heat from the engine compartment? But if you don't like the looks of one I understand. By "vents" I assume you're referring to louvers?

[dsraven]

cowl behind engine with the grille in front of windshield goes directly to the footwell vents on each side and then to a very small drain hole in the bottom of that plenum on each side. there is a fairly narrow access area below the hood on the firewall that you could put some air outlets from the engine bay that could feed into that area but the air would basically have nowhere to go except into the cab or out the grille in front of the windshield. you would possibly be better off with venting through the inner fenders.
why is the big block running so hot? does it take up too much room so the fan can't get the air to exit around the engine? how does the air flow path of the cooling air look, what do you have for direct access for cooling air to enter and exit the rad area (other stuff in the way like a big grille or driving lights or a/c and trans coolers etc), is there a fan shroud or is it electric fans?
the attached pic shows the firewall cut out and a new piece mocked up. youi can see above that sheet where the cowl basically ends and the firewall starts. the area above the sheet would be the narrow access to the area in front of the windshield where that grille is. you can also see the inner cowls have been removed for replacement and how that area looks. the next pic shows the new inner cowls and how they taper to a point with a small drain at the bottom. the drainhole would have had a small piece of sheet metal screwed over it to partially occlude the exit and leave a small opening that varmits can't get into but water could drain out. this is the reason this style of truck usually needs the inner vents, hinge pillars and floor replaced. the vent holes plug with debris and the cowls fill up on rainy days, then the water exits through the footwell vents onto the truck floor and rots things out.
hope that helps.

[mr48chev]

Had to read the question about three times and I still can't decide if you have an engine that is running hotter than you feel it should or if you have and excess of trapped air under the hood.

To do what you are asking about you would have to block off air flow to the vents and insulate the daylights out of the cab interior side of the plenum for the vents. I'm still not sure if if you will have airflow in the direction you want to draw air out at the bade of the windshield though. It may actually push the air back into the engine compartment at speed or severely disrupt the flow and create a disturbance in he air inside the engine compartment

It's been close around 43 years since I had a TF truck when I had a 57 panel in the mid 70's so I can't remember if there may be a way to vent the air though the back end of the inner fenders and maybe run what amounts to a road draft tube but much larger around and down behind the wheels and into the air flow under the truck. That would create a venturi effect at the end of the tube at speed but wouldn't be much help at low speeds except to let then fan push air out though them.

Or you could do like my grandfather did on his 1 ton and set a stick on the cowl so it propped the back of the hood enough to let hot air out. He did it to get engine compartment air on the windshield to defrost it but it would help air escape.
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[mick53]

On my 53 I'm playing with an idea of putting a second hood under the real hood to create a plenum of sorts. Then piping 2 small speed controlled fans up to the plenum from the left and right side of the radiator One on the drivers side to supply cold air to the carbs and the one on the passenger side to blow cold air down on the headers. Just another crazy idea I have rolling around in my head. I'm a long way from body work.

[lynx5653]

Thanks for all the info and suggestions. Will come up with a solution. Down draft tubes through inner fender sounds like a viable option. when engine was in my 90 gmc I could have cooked steaks on the hood.

[dsraven]

a pic of the underhood area and the grille area may help us help you.
is the rad sized big enough for the engine?
is the fan sized big enough for the rad?
does the fan have a good fitting shroud to allow the fan to move air properly?
is there adequate room to allow air flow past the grille and engine so the fan can do it's job of moving air?
does the truck sit really low so the air flow from the engine bay that is directed under the truck has a difficult time exiting?

if the engine is running within the normal temp zone and not overheating then the cooling system is doing it's job. you can insulate the hood and firewall if it is the hot sheet metal you are worried about. most newer vehicles have insulation in those areas for sound deadening and heat insulating. you can wrap the headers or exhaust system under the hood to help insulate the heat from those as well.

[mr48chev]

Anything you do to insulate the hood will keep heat in rather than get it out of the engine compartment.

If everything is in place and works as it should air flow should evacuate most of the engine compartment heat out and away from the truck as you drive down the road.

To go along with that have you done anything to create an airflow issue? Sometimes our great looking custom inner fenders or other pieces may block the natural airflow that was there before.

On the other hand if the engine never runs hot under any situation you probably don't have a real engine compartment heat problem outside of the heat transferring into the cab because you don't have effective insulation. I've got that in an OT truck that has half the floor mat and padding missing and a hot floor.

[_Ogre]

compared to new vehicles our trucks have lots of airflow under the hood
bbc and sbc run the same temperature, not sure what your trying to do
i wouldn't worry about what ever you perceive as the issue

[dsraven]

if the issue is the hood getting bbq hot then the fix may be as easy as insulating the hood on the under side. if the issue is the engine overheating or running hot that is a separate issue to look at.

[lynx5653]

Once I get truck back on the road I see if it holds as much heat under hood as my 90 did if so I will find fix at that time.
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[duramax55]

hi you could get some louvers punched in your inside fenders and or on the hood if you like that look

[_Ogre]

if you insulate the underside of the hood, prepare to use a prop rod as the stock springs won't hold it up anymore
i ran into a guy that sprayed bedliner under hood who had to use a prop rod

[my56chevytruck]

Originally Posted by lynx5653

Thanks for all the info and suggestions. Will come up with a solution. Down draft tubes through inner fender sounds like a viable option. when engine was in my 90 gmc I could have cooked steaks on the hood.

I'm running a 454 in my 55 2nd series and fortunately I'm not having any overheating issues. My 1st question is, how hot is overheating to you? what temperature is it running that is to hot? Don't know where I saw it, but theres someone on this forum has louvered his inner fenders.

[lynx5653]

truck is not running hot or over heating I am talking about heat trapped in engine bay and making hood and fenders very hot.

[MD2020]

There is NO heat TRAPPED under the hood if you drive your truck, it goes out the bottom.

(: