G'day fellas, I understand this question may have been discussed a thousand times but here we go. The cause of the bow in the NACA hoods, is it from poor quality with production, wrong jig, bad fibre glass or pressure from the hood springs pushing forward onto the hood pins causing the hood to bow or is it heat from the engine bay etc etc etc or does all the above apply? I'd like to know & there may not be one answer, your knowledge & information will be appreciated, thank you.
Quote from: Benny on April 29, 2022, 07:53:38 PM
G'day fellas, I understand this question may have been discussed a thousand times but here we go. The cause of the bow in the NACA hoods, is it from poor quality with production, wrong jig, bad fibre glass or pressure from the hood springs pushing forward onto the hood pins causing the hood to bow or is it heat from the engine bay etc etc etc or does all the above apply? I'd like to know & there may not be one answer, your knowledge & information will be appreciated, thank you.
I can sense your frustration. Any one of those things or a combination could be the cause of the bow but probably not all on the same hood. There are things that you can do to strengthen the hood but that requires surgery to the structure. There are a number of things you can do to address the symptoms . Some hoods never have a problem.
Also ad to all those causes the color (dark colors) of the car in the hot sun with a 428 running hot in traffic vs a white 351 car!
Hi there,
cause of the bow is engine and ambient heat + 50 plus years + factory stock springs on the hinges.
When we painted both our 1969s the craftsmen that worked on our cars used a tried and true method to some what correct the issue.
Each hood sat outside for months in the Florida sun. Cement blocks where carefully placed on the bends. Over a period of time this eased the bend. Once it was some what acceptable, it was prepped and painted. We purchased lighter hood springs that are adequate in holding the hood up.
Good luck
Not a Guru - just a regular guy
Why does this matter? It's just the way it is, the cars are 53 years, let it go.
Quote from: Bob Gaines on April 29, 2022, 08:05:29 PM
Quote from: Benny on April 29, 2022, 07:53:38 PM
G'day fellas, I understand this question may have been discussed a thousand times but here we go. The cause of the bow in the NACA hoods, is it from poor quality with production, wrong jig, bad fibre glass or pressure from the hood springs pushing forward onto the hood pins causing the hood to bow or is it heat from the engine bay etc etc etc or does all the above apply? I'd like to know & there may not be one answer, your knowledge & information will be appreciated, thank you.
I can sense your frustration. Any one of those things or a combination could be the cause of the bow but probably not all on the same hood. There are things that you can do to strengthen the hood but that requires surgery to the structure. There are a number of things you can do to address the symptoms . Some hoods never have a problem.
Thanks Bob, your experience & wealth of knowledge is greatly appreciated. Its good to hear there may have been a numbering of contributing factors to why some hoods may have bowed whilst others didn't, cheers.
Recently bought a 70 shelby out of Alaska and it had very little hood bow but the guy only drove it in the winter at night ALL NIGHT no hot sun problems there!!!!!!!
My vert spent it's normal life in France and Belgium before I coddled it in 1985. No bow here without springs. I recommend no springs on a 68-70. You can install light tension "Branda" springs by hand for shows or use a prop rod or I think Mr Gains used a chain method before on the hinges. My friend's Gt500 red car has one of the worst bowed hoods I have seen to date and my GT350 red has one of the best. It spent many years in Texas.
Bow? What Bow(pic below).... Seriously I was going to take my friend's hood and do what Tony said he did in his post with weights. Then if that didn't work make cuts on the inner hood with weights but I would also cut out a template to see the progress if any without mounting the hood back on the car. Good luck
Quote from: shelbymann1970 on April 30, 2022, 07:15:25 AM
My vert spent it's normal life in France and Belgium before I coddled it in 1985. No bow here without springs. I recommend no springs on a 68-70. You can install light tension "Branda" springs by hand for shows or use a prop rod or I think Mr Gains used a chain method before on the hinges. My friend's Gt500 red car has one of the worst bowed hoods I have seen to date and my GT350 red has one of the best. It spent many years in Texas.
Bow? What Bow(pic below).... Seriously I was going to take my friend's hood and do what Tony said he did in his post with weights. Then if that didn't work make cuts on the inner hood with weights but I would also cut out a template to see the progress if any without mounting the hood back on the car. Good luck
Oui, oui the weights over a period if time, tames the hump
Quote from: 427hunter on April 29, 2022, 11:10:19 PM
Why does this matter? It's just the way it is, the cars are 53 years, let it go.
+ 1
Quote from: Special Ed on April 30, 2022, 06:50:02 AM
Recently bought a 70 shelby out of Alaska and it had very little hood bow but the guy only drove it in the winter at night ALL NIGHT no hot sun problems there!!!!!!!
Eddie, Eddie, Eddie you know that :
Extraordinary claims require extraordinary proof....
On my 68, the fiberglass hood bowed with the stock springs trying to close it. I removed the springs and drilled holes in t the hinges that aligns in the open position. I used hood pins on lanyards to lock the hinges when open.
Quote from: Cobrask8 on April 30, 2022, 08:16:47 AM
On my 68, the fiberglass hood bowed with the stock springs trying to close it. I removed the springs and drilled holes in t the hinges that aligns in the open position. I used hood pins on lanyards to lock the hinges when open.
On my 68 I used a prop rod to keep it open. Then hand installed the light tension springs. I could also remove them by hand. Did it more than a few times at car shows. Hood was definitely "different" with the light tension springs VS no springs. I sold the car 6 months after buying "some red Mach1". Gary
Putting weight on the hood in the hot sun or otherwise so to push it back into shape is not typically a long term solution. It will most likely bow again under the same heated conditions.The only sure fire permanent solution I am aware of is to notch and add small sections to the inner structure so as to add tension and compensate for the flex/bow.
Believe these are the ones we purchased
Quote from: FL SAAC on April 30, 2022, 09:47:52 AM
Believe these are the ones we purchased
Those will still allow a hood to bow. When I stored my vert at a friend's garage for 6 months when I went to see it my hood was BOWED with those springs as I forgot to take them off. Took them off and the hood relaxed back down over time.
Quote from: shelbymann1970 on April 30, 2022, 10:15:55 AM
Quote from: FL SAAC on April 30, 2022, 09:47:52 AM
Believe these are the ones we purchased
Those will still allow a hood to bow. When I stored my vert at a friend's garage for 6 months when I went to see it my hood was BOWED with those springs as I forgot to take them off. Took them off and the hood relaxed back down over time.
Good Lawd almighty I gots to take a them off B 4 it's to late !
Quote from: FL SAAC on April 30, 2022, 09:47:52 AM
Believe these are the ones we purchased
Unlike what Branda's description says those lighter tension springs were only used in 1967 production but that is beside the point. The light tension springs can be a good compromise between what was engineered and proper function to address the bow of the hood. Less tension equals less bow on a weak structure hood. Of course no tension means no bow but having no spring or putting a length of chain in place of the spring when the hood is up is a hassle (although the hood will never fall with the chain in place). Also the hoods were designed to stay up with the larger stock springs so when using the light tension springs it doesn't take much of a breeze etc, for the hood to fall. You have to keep a eye on them at a show so as not to have a hood slam down on someones head or hand. Fixing the inner structure so as to allow the use of the proper stock tension spring is the solution to make the hood perform as engineered but admittedly it is much more involved compared to any of the compromise fixes.
Quote from: Bob Gaines on April 30, 2022, 10:44:53 AM
Quote from: FL SAAC on April 30, 2022, 09:47:52 AM
Believe these are the ones we purchased
Unlike what Branda's description says those lighter tension springs were only used in 1967 production but that is beside the point. The light tension springs can be a good compromise between what was engineered and proper function to address the bow of the hood. Less tension equals less bow on a weak structure hood. Of course no tension means no bow but having no spring or putting a length of chain in place of the spring when the hood is up is a hassle (although the hood will never fall with the chain in place). Also the hoods were designed to stay up with the larger stock springs so when using the light tension springs it doesn't take much of a breeze etc, for the hood to fall. You have to keep a eye on them at a show so as not to have a hood slam down on someones head or hand. Fixing the inner structure so as to allow the use of the proper stock tension spring is the solution to make the hood perform as engineered but admittedly it is much more involved compared to any of the compromise fixes.
+ 1 I can attest to that, once at a car show a fella was almost inside my engine compartment and boom that hood came down like a gator being fed chicken
Quote from: Bob Gaines on April 30, 2022, 10:44:53 AM
Quote from: FL SAAC on April 30, 2022, 09:47:52 AM
Believe these are the ones we purchased
Unlike what Branda's description says those lighter tension springs were only used in 1967 production but that is beside the point. The light tension springs can be a good compromise between what was engineered and proper function to address the bow of the hood. Less tension equals less bow on a weak structure hood. Of course no tension means no bow but having no spring or putting a length of chain in place of the spring when the hood is up is a hassle (although the hood will never fall with the chain in place). Also the hoods were designed to stay up with the larger stock springs so when using the light tension springs it doesn't take much of a breeze etc, for the hood to fall. You have to keep a eye on them at a show so as not to have a hood slam down on someones head or hand. Fixing the inner structure so as to allow the use of the proper stock tension spring is the solution to make the hood perform as engineered but admittedly it is much more involved compared to any of the compromise fixes.
I have the perfect answer; I show my car with the hood closed. That is the natural state of the car. If someone wants to see the engine I'll lift the hood momentarily. Unless you have some "bling" engine you want to show off that is the center piece of your car I think the best way to views these cars are with the hood closed. Of course my opinion. I' next to a friend's 67 Vette and a friend's 69 B9. Both have their hoods open. I'm just showing I practice what I say.
Check out my post in the "Services Offered" section. If you want that hood fixed permanently, . . . . . . . .
on one of the 69 hoods I had in the past there was a really big bow in drivers side.....I laid towels down on both fenders......laid a 40lb bag of potting soil down on both sides of hood.....let car sit all day in 95 degree heat and now no bow......
Quote from: Bob Gaines on April 30, 2022, 09:46:51 AM
Putting weight on the hood in the hot sun or otherwise so to push it back into shape is not typically a long term solution. It will most likely bow again under the same heated conditions.The only sure fire permanent solution I am aware of is to notch and add small sections to the inner structure so as to add tension and compensate for the flex/bow.
Bob, you being a concours judge I find it hard to believe you would suggest such a thing. Oh the horror of it 🙀😉
Roy
Quote from: TA Coupe on May 01, 2022, 04:44:25 PM
Quote from: Bob Gaines on April 30, 2022, 09:46:51 AM
Putting weight on the hood in the hot sun or otherwise so to push it back into shape is not typically a long term solution. It will most likely bow again under the same heated conditions.The only sure fire permanent solution I am aware of is to notch and add small sections to the inner structure so as to add tension and compensate for the flex/bow.
Bob, you being a concours judge I find it hard to believe you would suggest such a thing. Oh the horror of it 🙀😉
Roy
Roy, I know that was said all in fun but It should not be hard to believe that I would much rather see a hood that looks like it is supposed to from the factory rather then one with a horrible looking bow,the wrong springs ,or no springs. That factory look is the goal of any repair and the expectation in concours. How you get there is the challenge. You can attain that goal by doing strategic surgery to the hood inner structure as has been talked about by myself and others . That process includes making the inner structure look like factory untouched when done. Just like any other fiberglass repair some are better at doing it then others. With that all said the other compromise fixes may be perfectly fine depending on the persons expectations . I am about helping maintain within reason and not always just concours perfect. It is better to do what is best for you IMO.
Ok, now for my dumb question. What is the process for removing the springs. I am going to try taking mine off for a bit and seeing how that impacts my bow.
I have always used a long wooden handle screw driver to remove the springs On mine. I run the shaft of the screw driver through the attaching loop of the spring, holding the handle in one hand and the shaft of the screw driver in the other. Mine have always come off easily using this method. I take them off over the winter, and this has allowed the hood to just relax back into it's normal contour. The car is 53 years old and unrestored, and I've never had any form of serious hood arch doing this.
Quote from: eric lipper on May 11, 2022, 04:39:49 PM
Ok, now for my dumb question. What is the process for removing the springs. I am going to try taking mine off for a bit and seeing how that impacts my bow.
I use the space saver spare hold down hook that you should already have in your car. Have a prop rod, stick ,whatever to hold the hood up after you successfully detach the springs.