Hood scoops 71 Mach 1

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Help against what?

It doesn't hurt anything if you remove the block off plates. It would be something like a fresh air intake. It has been done like that for decades. Me too before I installed ram air. I simply removed the block off plates and did not anything further. If you have an air filter element it would not hurt anything, you will get dirt and dust through any of the other openings as well.

So get your easy mod and unbolt them!
 
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or, because your inserts already are formed to fit correctly, just drill like a zillion holes in them. OR get a functional ram air system and install a electric vacuum switch so you can open and close flappers at will.
 
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Removing the block-off plates can reduce the air flow through the radiator if you don't duct it directly into the induction system (carburetor/air filter). The hood scoop will act to increase the pressure inside the engine compartment...that increase in pressure results in reduced flow through the radiator. Liquids and gases flow from areas of high pressure to lower pressure. If the air pressure were to be equal on both sides (as when the car isn't moving or no fan), no air flows across the core. Ducting the air directly into the carb isolates the high pressure to the induction....that is the function of ram air.

Is the pressure increase enough to cause a problem? I don't know, but something to keep in mind.
 
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From what I have seen you should make sure your hood latch is in good shape when opening the scoops. That does cause an up force on the hood at speed that can damage or fail your primary hood latch over time. That is one of the reasons all Ram Air cars have the twist locks. They are a secondary functional latch for the additional force on the hood.

Of course if your car has gremlins like mine and you can never trust it on the highway you have nothing to worrry about anyway. ;-)

Kcmash
 

Retired2014

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Before I retrofitted to ram air, a bird removed one of mine at speed. Quite startling when you brace for windshield impact and it disappears before your eyes… but wow, what a mess under the hood. And I never found the missing block-off plate.
 
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Mine have been out for years. No issues other than few more bugs in the air filter.
Does it hurt or help if I removed the plastic covers on my 1971 Mach1 hood scopes and replaced with screen mesh?
I tried searching but could not find this question asked before.
Removing the hood block offs was the very first "Mod" I ever did in1973. My H.S.buddy looked at my pride and joy Mustang and condescendingly stated "YOU HAVE FAKE HOOD SCOOPS!" After school I went home and took 'em out. Next day at school no more fake scoops!
 
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Don't remove them - drill 'em! (sorry Tim) I drilled my plastic scoop bungs out last year for attempting to let more cooler fresh air move through the top end of the engine, (air cleaner area)which should help or assist to some extent the engine running cooler when the car is in motion. To what accurate extent or how effective this is, is really a guessing game. A ram air system is the better way to go of course for a direct cool air delivery to the air cleaner/carb for sure, hands down. However, for me, setting up with an aftermarket complete Ram Air system from scratch, is way too expensive, especially living in Australia.

Regards the pressure issue - i haven't noticed any changes or discrepancies as yet in that regard. I do monitor my water temp a lot when driving around or in stationary traffic throughout the year and seasons.

Regards the effect on running temps - when stationary, there have been no changes from before as you would expect. When moving out on the road from stationary, i have noticed the engine cools back down to and settles on180F very fast compared to before i drilled the bungs out. That has been a noticeable change. So there is a definate positive cooling effect taking place here from what i have done. Drilled out bungs, makes the scoops better looking in my opinion as well.

Regards dirt, bugs and water issues - no noticeable dirt issues under the hood, and because i never wash my car or drive it in wet weather, water under the hood is not an issue for me. Don't dive my car at night, only very rarely, so bugs are not an issue either.

Lastly, the front face surfaces of the bungs should have a honeycomb pattern imprinted on them. Simply use this pattern as a template for drilling out all of the holes. I didn't remove my bungs when i drilled 'em. Just drilled them in place. If drilling from front, lay down some protective tape or the like to protect the paintwork on the hood. It's easier to start with a small dia long shank drill bit , say, 1/8th dia, and drill a pilot hole in the center of each honeycomb circle. Now come in from the back and drill out each pilot hole with the selected diameter drill bit. Select a drill bit with the biggest diameter each honeycomb circle will allow. I bought a back up pair of bungs and kept them aside in case there might come a day when i want to bring the hood back to standard scoop cover.

Conclusion - for me, i'm glad i did this. There has been gain and benefit in the process. It used to bug me that you had this beautiful designed Nasa hood with the sexy scoops, and two useless plastic bungs blocking off any air flow through at all to the engine bay. It made sense to me to put the scoops to work then not at all. No regrets.

Greg.;)
 
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Duncan Mach72

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When I first had my car I removed the bungs. The engine used to breathe oil fumes & I found at low speed sometimes visible smoke came OUT of the scoops. Also I was inhaling it via the vent system inside the car - yuk! Eventually I got a plenum, the repro interconnecting ducts without doors, modded a stock base & I had functional ram air.
 

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Removing the block-off plates can reduce the air flow through the radiator if you don't duct it directly into the induction system (carburetor/air filter). The hood scoop will act to increase the pressure inside the engine compartment...that increase in pressure results in reduced flow through the radiator. Liquids and gases flow from areas of high pressure to lower pressure. If the air pressure were to be equal on both sides (as when the car isn't moving or no fan), no air flows across the core. Ducting the air directly into the carb isolates the high pressure to the induction....that is the function of ram air.

Is the pressure increase enough to cause a problem? I don't know, but something to keep in mind.
This is a non-issue, as the intakes are in a low air-pressure area on the hood, with the location actually being very poor for "ram-air". Cowl induction is actually better, with a high pressure area formed by the air hitting the windshield.
 

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When I first had my car I removed the bungs. The engine used to breathe oil fumes & I found at low speed sometimes visible smoke came OUT of the scoops. Also I was inhaling it via the vent system inside the car - yuk! Eventually I got a plenum, the repro interconnecting ducts without doors, modded a stock base & I had functional ram air.
Thanks, not something I think I could do. I will leave well enough alone.
 
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This is a non-issue, as the intakes are in a low air-pressure area on the hood, with the location actually being very poor for "ram-air". Cowl induction is actually better, with a high pressure area formed by the air hitting the windshield.
In that case, it might actually improve flow through the radiator! It certainly helps to understand the boundary conditions. Considering the cross sectional areas involved, the effect is probably minimal whatever it may be.

I wonder if there are any youtube videos of 71-73's in a wind tunnel. That would be pretty cool to check out.
 
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In that case, it might actually improve flow through the radiator! It certainly helps to understand the boundary conditions. Considering the cross sectional areas involved, the effect is probably minimal whatever it may be.

I wonder if there are any youtube videos of 71-73's in a wind tunnel. That would be pretty cool to check out.
It would be cool to see but I am pretty sure after all the 71-73 mustang searches I have done on YouTube that I would have come across one. Sadly, I have not but on the good side, I see more and more 71-73 mustang videos lately.

Tom
 

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Don't remove them - drill 'em! (sorry Tim) I drilled my plastic scoop bungs out last year for attempting to let more cooler fresh air move through the top end of the engine, (air cleaner area)which should help or assist to some extent the engine running cooler when the car is in motion. To what accurate extent or how effective this is, is really a guessing game. A ram air system is the better way to go of course for a direct cool air delivery to the air cleaner/carb for sure, hands down. However, for me, setting up with an aftermarket complete Ram Air system from scratch, is way too expensive, especially living in Australia.

Regards the pressure issue - i haven't noticed any changes or discrepancies as yet in that regard. I do monitor my water temp a lot when driving around or in stationary traffic throughout the year and seasons.

Regards the effect on running temps - when stationary, there have been no changes from before as you would expect. When moving out on the road from stationary, i have noticed the engine cools back down to and settles on180F very fast compared to before i drilled the bungs out. That has been a noticeable change. So there is a definate positive cooling effect taking place here from what i have done. Drilled out bungs, makes the scoops better looking in my opinion as well.

Regards dirt, bugs and water issues - no noticeable dirt issues under the hood, and because i never wash my car or drive it in wet weather, water under the hood is not an issue for me. Don't dive my car at night, only very rarely, so bugs are not an issue either.

Lastly, the front face surfaces of the bungs should have a honeycomb pattern imprinted on them. Simply use this pattern as a template for drilling out all of the holes. I didn't remove my bungs when i drilled 'em. Just drilled them in place. If drilling from front, lay down some protective tape or the like to protect the paintwork on the hood. It's easier to start with a small dia long shank drill bit , say, 1/8th dia, and drill a pilot hole in the center of each honeycomb circle. Now come in from the back and drill out each pilot hole with the selected diameter drill bit. Select a drill bit with the biggest diameter each honeycomb circle will allow. I bought a back up pair of bungs and kept them aside in case there might come a day when i want to bring the hood back to standard scoop cover.

Conclusion - for me, i'm glad i did this. There has been gain and benefit in the process. It used to bug me that you had this beautiful designed Nasa hood with the sexy scoops, and two useless plastic bungs blocking off any air flow through at all to the engine bay. It made sense to me to put the scoops to work then not at all. No regrets.

Greg.;)
I love the idea of making them open honeycombs. I have been planning to do the same thing so I can put an led just inside the honeycomb and make the scoops glow at night. Do you have any pictures of them?
 
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In that case, it might actually improve flow through the radiator! It certainly helps to understand the boundary conditions. Considering the cross sectional areas involved, the effect is probably minimal whatever it may be.

I wonder if there are any youtube videos of 71-73's in a wind tunnel. That would be pretty cool to check out.
IMO, not sure about that as the rpm’s increase, the stock fan blades “spool up” and expand in towards radiator face and their OD is well past the ID of the shroud creating x?cfm of flow through it which I doubt would be affected by any air going into the open ducts on the hood and swirling about unmanaged. I could envision plug wires, accessorie wires, vacuum lines/hoses, etc. being whipped around in the engine bay like crazy with the intake air not being funneled into a “functional” cold air box pumping directly into the intake manifold. A set of go pros mounted by the battery and WS washer reservoir for an experimental video would be cool to see if any of you that are running open ducts would take that on.
 
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