I have a 40 Buick Special Coupe with a BBC and a 700. I has a mechanical fan with shroud that seems to work well, however while cruising around in the summer the hood gets so hot you cannot put your hand on it (Already ruined the paint). I am wondering if I can add an electric fan ? And of so would it make any difference ? Thanks in advance for any advice you may have.
It sounds more like an engine compartment issue, rather than an overheat issue. Maybe opening up (or removing) the inner fender panels would help getting the heat out of the engine compartment
Do you have a good temp. gauge mounted in the right spot? Knowing the actual engine temp. is where you should start. If your engine is running too advanced, you will get overheating problems.
You've got a 350+ hp (I assume) engine producing heat in a space previously occupied by a 110 hp engine, so expect there to be a LOT more under hood heat (assuming a 70% engine efficiency, 105 hp of heat now vs. 33% hp in stock form). You need airflow to get rid of it. As much as many guys on here will argue against it, consider an electric puller fan (mounted behind the radiator) to move more air thru. The mechanical fan you have changes air movement volume with engine rpm, an electric is constant volume. A shroud is critical, so you are ahead in that department. Look at air escape paths to see if they are obstructed, as well as air inlet areas. Are you running manifolds or headers (headers tend to radiate mor heat). If headers, you might try wrapping them. Good luck!
open up the inner fenders a bit, and mount a couple computer fans in the opening. Did it on a 62 Falcon with a BBC stuffed in it. Worked like a dream. You could feel the heat leaving from the wheelwells.
The 40 engine compartment, although long is quite narrow, especially in the front. What size mechanical fan are you running? Clutch fan? Type of radiator? Shroud? Headers? (which add a lot of heat). What coolant temperature are you reaching? The original inner fenders fit down around the chassis pretty tight, and does not release a lot of heat. If engine temp is OK, more air flow in the compartment is needed. I am currently building a 40 also except using a 401 nailhead. I too am concerned about engine compartment heat, and plan to use an ample clutch fan and custom radiator w/shroud. I will PM you about more specifics about your car if OK
You could also add some insulation to the inside of the hood, there are several brands that are peal and stick and a lot of the early cars used insulation under the hood. HRP
Getting heat out from under the hood is a typical 55-57 Thunderbird problem. In a car that normally cools ok but overheats in traffic or a parade it’s common to open the hood (front hinged) to let the air out. If you’re ok moving or even idling, adding a fan problem won’t help much. In that case the under hood insulation or opening up the fender wells etc. as suggested above would be the solution. Or, since you’re from 20 miles south of me, just don’t drive it the 5 hot days a year we have.
The OP notes nothing about the car overheating. From what he says the heat isn't escaping out of the engine compartment. An electric fan? What are you going to do? Mount it pointing out the bottom to draw the heat out the bottom? You need to open up the engine compartment to let the hot air escape.
Thank you, Exhaust wrapped back to mufflers so I think as mentioned many times here I need to figure a way of getting heat out. Inner fenders have large open space but I am wondering if heat is trapped up under the hood. Thanks aghain
The car does not really overheat. Gets up to 110-20 on the hottest days. I am thinking that opening the engine compartment up some how might be the answer. already have large opening in the inner fenders but thinking that heat may be getting trapped up under the hood. Don't think I want to louver it. Thanks for your help.
Yeah but those 5 days are car show days , Thanks for the help, I have large openings in the inner fender but will be looking at under the hood insulation next.
Thank you for your help, I have pretty good size openings in the inner fenders. The fan is stock 454 with a after market shroud and I took the original radiator to the radiator shop and had them build me a new one in the same configuration so it would fit in the car. I am thinking that some kind of under hood insulation might be the next step. By all means pm me but it took me 3-4 days just to figure out how to reply to all the responses I got so I dont know how the pm thing works yet .
Might want to look at nascar and other race cars, not just about getting air out, but getting air in as well. on forklifts the air is pulled up off the floor , under the unit and then pushed through the rad and out the back with as big a mechanical fan they can stick on the engine . on some larger units in high demand applications they will lover the hood sides add extra fans on the steps to push more air into and out of the unit. You simply ( or not so simply) have a dead spot under your hood with crappy circulation.
Most modern cars have a bit of an air dam below the radiator. It is not for fuel economy aerodynamics, it is to create a low pressure area below the engine to scavenge air out of the engine compartment, below the floor pan.
“however while cruising around in the summer”. If you’re running down the road at say, 30mph, can you pull off and the hood is cool? Is it only a low speed effect, or stopped? I’m trying to be helpful here. If it’s a low speed or stopped problem, but not a problem at speed, maybe a fan would help. Or replacing the existing with an a/c fan and clutch, they put enough of those on BBC’s that it would be easy if you’ve got the clearance. And kidding aside, I get it. We don’t have enough really hot days up here to troubleshoot these kind of problems. I finally got the bird to where it will idle along at 90 or so and stay under 200 but it took a while.
Thank you for your response, I have recieved many suggestions and the thing that stands out is more air in and more air out.I don't want to louver so must look at other options. I am now considering hood insulation and an auxiliary fan to pull air out.
Does your hood open “ normally “ from the front hinged in the rear ? the reason I ask is you can install some shims on the rear hinges and pop the rear of the hood up 1/2” or so. I had heat issues on a pretty stout ( sounds funny) but 79 vw rabbit , and I did just that to let air escape , worked out great . Even if you don’t want to leave it like that , it will at least prove or disprove yours and our thoughts. An electric fan won’t do much , forcing air in or letting air escape is what you need you need to look into
The hood is clamshell, opens half from both sides. I have removed most of the rubber seal between the hood and cowl but no effect. If you look sideways at the car, you can see there is 4-6" of dead airspace above the carb and I think I am trapping the hot air up there. Don't want to louver the hood so thinking about insulation and some type of auxiliary fan. Thank you very much for your help, I will get this figured out eventually.
I have run without the hood and no more problem,, However I prefer to have the hood on and when I am running at 30-60 mph, it is not a problem. It is just that the hood gets so hot you cannot put your hand on it and it has already ruined the paint. With all the great responses I have received, I am thinking I will insulate next and then look into some sort of auxiliary fan.
Functional ventiports on the fenders or hood sides would probably do wonders on keeping underhood temps down.
If the OUTSIDE of the hood gets hot enough to burn the paint just about anything under the hood is getting cooked slowly. Anything electronic in there will have a very tough life (upgraded ignition, alternator and so on), fuel may boil in the carb... Insulating the hood may help the paint survive, at the same time it brings the under hood temperatures up even higher. A few pictures may help the people that don't know how this engine bay looks suggest solutions, or perhaps spot a problem.
110-120? or is that a typo and you meant 210-220? If it is indeed 110-120, the first thing I would do is remove the shroud, as goofy as that sounds. That might give you a more 'spread out' airflow that would scrub the hotter, upper air out. Might raise the engine temp a bit, but if it's really 120, you've got a few degrees to play with. No louvers in the Pacific Northwet..... engines don't like rain showers!
It sounds like your intake of air through the grille and radiator is functioning okay but your hood is creating a dome with hot air inside. The air coming through the radiator is probably about 200* and then things like the exhaust manifolds are radiating additional heat into the "dome". Insulation may be a band-aide to help save the paint but it could also trap more heat inside the hood. Be careful that you don't turn your carb into a percolator. Focus on venting or pushing the super-heated air out. I know you don't 'want' to make cosmetic changes to your bodywork. But like an old friend of mine used to say, "People in hell 'want' ice water, too"
I'm thinking that there are some other issues going on with that car and it isn't engine temp as much as temp under the hood due to headers or exhaust heat. Someone didn't remove and fill in the side vents in the hood in the name of customizing perhaps? I don't know how much they actually vent the engine compartment if at all but that is a thought.
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