Fiberglass hood mods... crazy?

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Bill Dedman

Bill Dedman

bill dedman
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My '72 Valiant needs help in the weight-distribution department.

I have been considering a lightweight (race-type) flat, stock-appearing fiberglass hood and front bumper for it.

Here's my question; laugh if you want to, but I am dead serious and will welcome any replies... pejorative, ridiculing, demeaning, or otherwise...:profilel:

I want a pin-down hood that will be held in place by four "hood pins," and that's conventional, as far as I know (I'll remove the stock hinges.)

What is NOT "conventional," is, I want to cut that fiberglass hood into two pieces, laterally. That would mean slicing it straight across, about a foot ahead of its back edge.

Here's the scenario....

I want to place the rear hood pins about 14-inches forward of the back edge of the hood, and slice a 1-foot long, full-width, straight section off the back of that hood, and re-attach it with a "piano hinge," one of those long, simple, barn-door-like hinges that will allow the piece I sliced off, to lie flat in its original location UNTIL pressure from in the engine compartment builds up and forces the rear portion of the sliced-off section of the hood, to rise up (pivoting on the piano hinge) and let the air out, as I speed down the track. When I slow back down, gravity (and maybe a spring) will return the back side of that "flap" to its original location, flat against the inner fender panel hood-support "ridge."

If this will work, it should accomplish several things:

1. It will release trapped air that came through the radiator, assisted by the fan.

2. It will deposit air into the airstream at the base of the windshield, and the profile of this "flap", sticking up, will act as a "spoiler," disturbing the normally high-pressure air are at the base of the windshield. Whether this will help move that air over the top of the windshield is debatable; it could hurt more than it helps; we'll see.

3. The structural strength of the hood may be increased by the attached hinge, which will go all the way across the hood, with no break in the attachment configuration. Should make the hood more solid, hopefully.

4. May slightly lower underhood engine temperatures due to increased air-flow though the engine compartment.

Have I lost my mind, or could this actually work as planned???????

Any and all comments welcomed. I need to know whether this is Alzheimer's related; God knows I'm old enough....

Just tryin' to get that ol' Valiant into the good 11's...

Let me know what you think! Please.........:read2:
 
wow thats a cool idea. i think the only issues you would face are the hinge. stock hoods are not 100% flat so they will hit when lifting either side. so space them a lil ways between each other and cover with a small piece of rubber maby. will the front piece come all the way off when you take the pins lose? the other issue would be weight of the hood. i dont think air from the engine compartment will lift it. it still has some weight to it even if its glass plus the wind will want it to stay down. so maby an air grabber type set up thet you can open when you want to then close when you are bein sneaky lol
 
so you want to do something like the Chevy hoods have?
 
Its "different" to say the least lol. nothing I think I would personally attempt.

Let me ask why it is that you need to cut the hood in half though? if your goal is to have it flap up to release air then why not just cut an elongated rectangle in the hood towards the back of the hood and either have a permanently mounted windshield facing vent.

or stick with your idea of the flap design but just by cutting an elongated rectangle facing the back side of the hood.

Honestly, i think it may appear a bit gaudy and I would try to find a different way to accomplish your same goals but without it being as obvious.

for instance, if you are concerned with wind from under the car filling your engine bay and creating drag on the car then I would get a sheet of tin and fab up an under carriage cover and mount it with nuts and bolts to stop wind from gaining access to your engine bay. so wind is good though as it helps keep your engine compartment cool

I don't think I would worry to much about pressure created from your fan cooling your radiator.

as for the flap flipping up to act as a spoiler to push wind over your windshield......you already mentioned buying an aftermarket fiberglass hood to cut to accomplish your goals, why not buy an aftermarket fiber glass COWL hood that will do the same?.....it will push air up over your windshield and give some slight down force I suppose and it will act as an engine bay vent.

I honestly think you could accomplish the same thing you have mentioned by just installing a cowl hood and it would look clean and un modified all the while.

I applaud you for considering the modification and taking in account all the dynamics that would change with your idea but I personally think its a little over the top and unnecessary.

Either way you decide to go, I wish you luck on the car ....I just figured I would throw in my 2 cents on the subject.

Good luck!
 
A good bit of your desired results could be accomplished by removing the seal between the hood and cowl. That mod used to be illegal in Stock Elim, I wouldn't be surprised if they don't enforce it anymore.
Remember, any mods could allow water where it shouldn't be.
You could experiment w/ your stock hood. Remove the aforementioned seal, and also, try raising the rear of the hood by spacing the hinges some way.
I agree w/ others, I wouldn't want that big ol' chunk of hood flapping in front of me at 100+ mph. At the very least, you would need a way of keeping it from going too high.
 
Bill, always thinking aren't you. I told you guys that Bill thinks beyond the bun. He does like buns though as long as they are the right kind and attached to the right thing. A lot of 70 yr olds are done thinking , but not our Bill. I have a glass hood but i think it's for a dart/demon and it's a six pac with scoop. Dont think it will work for ya. If it will , let me know.
Small Block
 
Small Block said:
Bill, always thinking aren't you. I told you guys that Bill thinks beyond the bun. He does like buns though as long as they are the right kind and attached to the right thing. A lot of 70 yr olds are done thinking , but not our Bill. I have a glass hood but i think it's for a dart/demon and it's a six pac with scoop. Dont think it will work for ya. If it will , let me know.
Small Block
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Thanks for the kind words, Bill. It's not that I am always thinking, more, I believe, that I am just a little crazy, and always trying to wring another tenth out of this pile of bolts/money pit, sitting in my driveway.

I am pretty sure that the hood you have won't fit a Valiant. But, it was a nice offer!!! Keep me in mind... and, have a good week!!!8)
 
Small Block said:
Bill, always thinking aren't you. I told you guys that Bill thinks beyond the bun. He does like buns though as long as they are the right kind and attached to the right thing. A lot of 70 yr olds are done thinking , but not our Bill. I have a glass hood but i think it's for a dart/demon and it's a six pac with scoop. Dont think it will work for ya. If it will , let me know.
Small Block
Click to expand...

What year cars does it fit? If it's for a Demon, I would expect it to be a 71-72 hood
 
Have you seen the rear flaps on a Top Alcohol Funnycar? That same idea would work on the hood. As far as being a spoiler the underside pressure would have to be far greater then the topside in order to even act in the fashion your thinking about. The only way you could get it to work would be a locking mechanism when the flap reached a predetermined height.
 
SpeedThrills said:
A good bit of your desired results could be accomplished by removing the seal between the hood and cowl. That mod used to be illegal in Stock Elim, I wouldn't be surprised if they don't enforce it anymore.
Try raising the rear of the hood by spacing the hinges some way.
I agree w/ others, I wouldn't want that big ol' chunk of hood flapping in front of me at 100+ mph. At the very least, you would need a way of keeping it from going too high.[/quote]
Thanks!
I may try your suggestion to raise the back of the hood, and spend the money I DON'T use to buy a fiberglass hood, to buy a set of Cal-Tracs.:cheers:
Click to expand...
 
Dorian said:
Have you seen the rear flaps on a Top Alcohol Funnycar? That same idea would work on the hood. As far as being a spoiler the underside pressure would have to be far greater then the topside in order to even act in the fashion your thinking about. The only way you could get it to work would be a locking mechanism when the flap reached a predetermined height.[/quote]

Dorian,

I'm sure you're right about all of that. I was more concerned with getting the hot, excess air out of the engine compartment than I was about the spoiler effect, but I know that what you said is true.

Thanks for pointing that out! I should have known that...
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IgotDUST said:
Its "different" to say the least lol. nothing I think I would personally attempt.

Let me ask why it is that you need to cut the hood in half though?

I wan't going to cut it in half. I was going to cut a 12"-long section off the back, clear across the hood's diameter, and re-attach it with a hinge that would allow pressure from underneath to force the backside of it up, at speed, creating an opening from which trapped, hot air could escape.


if your goal is to have it flap up to release air then why not just cut an elongated rectangle in the hood towards the back of the hood and either have a permanently mounted windshield facing vent.

or stick with your idea of the flap design but just by cutting an elongated rectangle facing the back side of the hood.

That's exactly what I siad I would do, but replace it with the hinged piece so it wouldn't rain in (or, be visible from the other lane. LOL!)

Honestly, i think it may appear a bit gaudy and I would try to find a different way to accomplish your same goals but without it being as obvious.

I don't think a piano hinge, (have you ever seen a piano hinge?), which would be painted the same color as the rest of the hood, would be visible, much less obvious, from the next lane.

for instance, if you are concerned with wind from under the car filling your engine bay and creating drag on the car then I would get a sheet of tin and fab up an under carriage cover and mount it with nuts and bolts to stop wind from gaining access to your engine bay. so wind is good though as it helps keep your engine compartment cool.

Now, that is a great idea!!! Gotta look into that!

I don't think I would worry to much about pressure created from your fan cooling your radiator.

It's not the fan; it's the air that comes IN through the radiator (picking up lots of heat) that concerns me.

as for the flap flipping up to act as a spoiler to push wind over your windshield......you already mentioned buying an aftermarket fiberglass hood to cut to accomplish your goals, why not buy an aftermarket fiber glass COWL hood that will do the same?.....it will push air up over your windshield and give some slight down force I suppose and it will act as an engine bay vent.

I want to maintain a stock appearance. So far, I have dog dish hubcaps, a flat hood, and 37-year-old paint... a cowl-induction would destroy the stealth... LOL!

I honestly think you could accomplish the same thing you have mentioned by just installing a cowl hood and it would look clean and un modified all the while.

Uh.... a cowl-induction hood on a 4-door sedan... on the street....
I don't theenk so... :)

I applaud you for considering the modification and taking in account all the dynamics that would change with your idea but I personally think its a little over the top and unnecessary.

It probably is a waste of time, but I'm retired; what else have I got to do???? LOL!

Either way you decide to go, I wish you luck on the car ....I just figured I would throw in my 2 cents on the subject.

Good luck![/quote]

Thanks!!! I'll take it!!!:cheers:
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what if you lowered the cowl lol maby more work but could be cool or cut out all the firewall in front of the cowl so its all open. i know the heater might be wierd then lol but who needs heat when ur going fast lol
 
I honestly don't think that driving down the road you will have that much heat in your engine bay..you always have wind rushing in from underneath and the fan blowing in there.

The only thing venting the hood would do is maybe cool it down a few extra degrees but not enough that in my opinion would be worth the hastle of moding up a hood over.

and the vented hood will do nothing for you in stop in go traffic unless you have some kind of electric fans rigged up at the hole in the hood you creat to evacuate the engine bay air as you please.

I honestly think if what your looking for more then anything is to cool down the engine bay a bit...you could get out of it ALOT cheaper and easier.

I have done this before and maybe it would be something you would like to try.
I have taken dryer ducting and grabed a "scoop" shaped piece and mounted one of each on each side of the under side of the car and then take some dryer vent hose "aluminum foil spring looking thing" lol and route it into your engine compartment that way as your driving down the road it would scoop the air in and force the cool air into your engine compartment... I have also made ram air induction the same way but instead of running the ducts into free air inside the engine pay, I plumed it into the ducting for the air cleaner housing.
So as you drive down the road it forces cool air into the engine and actually makes a good bit of difference!.

anyhow...not sure if maybe that is something you would liek to try but i figured i would throw it out there!

lol....here is a quick example for everyone I put a good 2 minutes into lol...you should all get a laugh at the skill required to render such a portrait lol

Untitled.jpg
 
I ran a fiberglass hood on my 68 Dart back in the 80's and the way the Dart front end is designed, they do trap a lot of air. a teacher I had in high school had a 68 Dart drag car also and he had the same issue.

I played around with different ways to mount the hood and I found that if you use longer hood pins, you can make up a light spring that goes between the top of the hood and the pin. This allows the hood to rise a little when the air builds up in the rear of the engine compartment but keeps the hood tight when not racing. Just make sure your pins have a slight angle towards the front of the car or the hood will bind when it tries to rise up.

The piano hinge won't work unless you elongate the holes for the pins. when the hood tries to fold the pins will keep it from folding because when you fold something, it gets shorter but the pins will be stationary.
 
lol nice pic. that is a good idea tho!! and a whole lot easier then a hood or cowl mod maby do both. you could rig up some kinda temp guage so you can see if they help. like put one on ur block on the outside and run it as is then with the front ducting then run it then with the hood mod then run it. i dont know how much any of it will cool it down but it would be cool to see. you could hide the front vents behind lights or in the grill somewhere to keep the sneakyness
 
It actually does make a pretty noticeable difference , I built a (pardon my language) 93 chevy silverado GT stepside short bed regular cab 350 v8 auto race truck and ran the ram air ducting on it....truck ran very nice and had a good bit more of get up and go to it.

As for the cooling aspect of it. I am sure it would knock the temp of the engine down by alot as you can direct the cold air where you please such as directly on the block which would keep the engine cool and cool down the hole engine bay do to the extra wind in the hood area and the lower temps of the engine.

but again....won't see much difference in the stop and go traffic, pretty much a "in motion mod" lol.... hope this is something you will try!
 
I have a fiberglass hood and I want to do something to let that air out, I know how it builds up
 
For those of you who may not be familiar with the term, "piano hinge," this is what it looks like. There are holes in both sides (but, not in this picture) for attachment to the two surfaces that are to be hinged.

With the pivot rod on the top side, it shouldn't be necessary to slot the holes; it will just pivot on the continuous rod.

This will have to be in two sections, each one about 18" wide, and 12" long, because as someone pointed out, this hood is NOT "flat." TWO "flaps; one on each side....

Thanks for that info; I'd never noticed.

The rear hood pins will be ahead of the flaps, of course.

hinges.jpg
 
I want to try this, I dont really drive the car in the rain anyways. And I know what your talking about doing, Cut a piece and hinge that piece so the air has some were to go out and not create drag
 
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