Hi guys im new here an i have a problem. i recently ordered a fiberglass harwood 1107 hood scoop for my 78 ford f250. the problem im having is the contour of the scoop dont actually fit the hood. it has about a 1/4" to 1/2 " gap in the middle of the flange. i did some research an i found that i might have to use fiberglass to build the scoop up to match the hood contour. is there anything else out there that would make this job easier.
thanks guys
Ron

 

Is stead of building up the part that is short, can you cut down the other parts to lower it to fit the hood?

 

Real trucks don't need scoops....

 

bertha66 i will take a look at it. i never though of that. i thought to deep into it instead of thinkin small

 

i looked to see what i can do i have 2 pics that will better help explain my trouble. i dont think i can grind down the flange to make it sit properly because of strength an cracking issues. idk what i should do to fill that gap Image - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting
Image - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting

 

Kind of what you get when you buy universal parts which that scoop is, it's made to fit anything OK not one thing correct. Trim some and fill some, find a happy place in the middle.
It will always be a chevy style scoop on a ford though

 

yea im gunna have 2 i just want it for the looks but this weekend i will work on it an post how it goes

 

whats the best way to fill the gaps. from what i searched fiberglass wont work with a metal surface. what should i do. put sum bondo down as a base and then work the fiberglass mats from that?

 

I'd slice the scoop just above the flange, and then pull the flange down to sit flat on the bonnet, and fibreglass the gap between flange and rest of the scoop. If you try to build up the area underneath the flange I think it will probably end up looking like ****.

 

You need to use lath screws and pull the hood metal up and the scoop will pull down a little, When you get it all set with screws every 3 inches then remove one at a time and out in a good pop rivet with a washer so the glass wont pull threw, No you cant use fiberglass on metal it wont bond it has to be bondo...You should use a bonding agent like seam sealer before final attachment and make sure to drill holes in the front of the hood to drain water that will get caught up under the scoop.

 

Unless there full out race trucks... then there's usually little need for one...


I don't understand why people want to do this, the point of those scoops is to gain hood clearence for tall motors... just from guestimating, I figure a tunnelram, and blower would fit under on of our hoods without any modification...

 

No, ...the point to the scoop is to draw air in from the base of the windshield. Air rushing over the hood creates a vortex at the base of the windshield. The "Cowl Induction" hood scoop funnels the air from this vortex into the engine, for a cooler, denser air charge.

That being said, with the huge gap between the hood and carburetor, all the fresh air is lost in the engine compartment.

Back to the original post. No matter what you do, it will crack and peel and look like crap within a year. Fiberglass doesn't stick to metal. Thick bondo, ...won't stick to metal. Keep in mind, your hood is a huge piece of flat steel with few braces. It flexes A LOT! Anything you do to attach that scoop to the hood WILL come apart within a year. The only way to get a cowl scoop to attach to your hood so you never have to worry about it, is fabricate one out of steel and weld it to the hood.

I've also just Dzus-clipped fiberglass scoops down to steel hoods. If it were me, I'd modify the front of the scoop so it sat flush all the way back. Then I would glass a new flange to the scoop. Then I would Dzus clip it down to the hood. This way will last the longest and never look like you tried to glass a fiberglass hood scoop to a steel hood.

 

I would do exactly the same thing. I used to manage a couple of Speed Shops back in the 80's when this kind of stuff was popular. Any bonded on glass to metal scoop started to crack and seperate within 2 years and looked like monster crap especially when the guy really worked hard to eliminate the joint.

Just adjust the scoop flange so that it lays flush to the hood with glass mat from underneath, add Dzus fasteners all the way round to the flange, about every 4 inches, then paint it to match the truck. It will look tougher, work better and last longer than any other way. If you are concerned about sealing, add a line of thin foam tape to the underside of the flange to seal it off properly.

Eric

 

I understood what you're trying to say.. but unfortunately it's wrong. Corrections:

No, ...the point to the scoop is to draw in air from the streamline that travels just above the boundary layer on our hoods as we travel.



"Air rushing over the hood creates a vortex at the base of the windshield. The "Cowl Induction" hood scoop funnels the air from this vortex into the engine, for a cooler, denser air charge."

Just as a side note, a vortex would never be created above our hoods. If anything were to be created, it would be an eddie that would break off of our hoods due to the odd shape and un-streamlined design of our trucks. Not sure where you're getting this information from earthquake68...

The only way you can get a vortex to be created when travelling is between two vehicles. You cannot create a vortex with single vehicle travelling through the air.

 

I would beg to differ with both of you. Take a look at some racing car aero books about boundary layer and laminar flows before trying to explain. Let me take a shot at it for all of you and try to make it simple (its really not simple at all). I have been racing cars and engineering them since the early 80's, so I have a bit of knowledge.

There really are 4 types of air inlets (scoops). The ones you use are totally dependent on the type of vehicle you have and the need you have.

The first type is the most common style on drag cars, formula cars and submarines, . I call it the raised snorkel which is the huge forward facing scoop that has the opening about 6" or so above the hood. This type is used primarily when the frontal face of the vehicle causes a high pressure area at the leading edge of the hood that deflects the air up above the plane of the hood. Tink of it as a bow wave in a boat. Combined with a windshield that is streamlined enough to minimize or eliminate a high pressure area at the base of the windshield. These snorkel style of scoops work very well as they are way up in the flowing windstream and can capture cool air at or sometimes above atmospheric pressure due to a slight air compression in the scoop due to vehicle velocity. The so-called ram air effect can be both a good and a bad thing dependant on what type of air/fuel supply system you use. Works extremely well in most cases with downsides of loss of visibility and huge amounts of drag. Usually illegal on street vehicles.

The second type is any system that pulls air off the base of the windshield. This works extremely well when your windshield acts as a wall and a strong area of high pressure cool air exists at the base of the windshield. Dentsides are great at doing this and this should be the the type of scoop most often used.

The third type of scoops used are the low mounted forward facing scoops. These require a fair amount of airflow into them to work, but on most street cars and trucks the boundary layer airflow at the center of the hood is very slow or stagnant. I have even seen reverse flow in this area as the high pressure at the base of the windshield is high enough to overcome the flow caused by vehicle movement. If you stick these types up high enough to capture a faster travelling proper direction air stream in the laminar flow pattern, you usually end up with a snorkel style of scoop. I can't tell you the number of times we have done a yarn test and actually had reverse airflow coming out of the forward facing hood scoop as the air coming through the rad opening was looking for a way out.

The final type of scoop is based on the vehicle design that allows a high speed, highly energized boundary layer to pass over the area you want to draw air from. This type is usually referred to as a NACA duct and it requires a lot of high speed airflow that remains attached to the body and has to be placed in a flattish panel that receives directionally correct airflow that is cool. This is hard to do and that is why they are usually used on airplanes and formula style cars.

These descriptions above will usually drive aero engineers nuts, but I have tried to par down a book load of information into a few paragraphs. Needless to say the OP is going to use a cowl induction style scoop in a dentside. It should pickup a large amount of high pressure air from the base of the windshield if the opening is far enough back, like 4" from the windshield. He needs to seal the opening through the hood to a cold air box and air cleaner to his carb, to have any advantage at all. If not, I would leave the hood stock, get an enclosed air cleaner with 2 tubular inlets and run ducts through the engine compartment to 2 ducts at the bottom of the front bumper. Clean for airflow, great source of high pressure cool air and way easier and cheaper to do.

As always, your opinions may vary, but I do have a bit of experience with this type of thing.

Eric