can anyone help in the process of adding a hood scoop? Fiberglassing related.

[JeffP1167]

A project I started on my 82 vette was a making a L-88 hood. I would like to finish this project and sell the hood or include it in the sale of this car.

Basically I bought a long style piece a crap L-88 hood which was beyond junk! however I though about cutting the hood scoop out of this hood and adding it to my stock hood. The resin in the scoop is unknown so what resin would provide a good bond to it and the SMC? Also how do you achieve a smooth surface once you have glassed from the bottom to secure scoop to the hood?

Here are pictures of my progress now I need the help of fiberglassing it in place. Keep in mind the hood I bought was so weak that I actually feared driving the car with it on. This seemed like the better alternative in my case so I retain the perfect fit of the factory hood and the superior strength of one.

So anyone who can help that has experience in helping me finish this would be greatly appreciated.

he is my progress so far. Also the scoop could stand to use a few extra layers of glass since its pretty weak (just to help strengthen it as well.

the start of the project

heres the start of cutting the hole in the hood.

 

[JeffP1167]

Here is the hole all opened up. I need to graft in the rear raised section into the hoods inner fram that supports the back of the hood scoop as well

these areas are being pushed by the stock inner frame wich should be resolved by grafting in the L-88 rear inner frame portion.

keep in mind I still have a lot of fitment work to do

 

[JeffP1167]

Obviously in this trimming still needs to be done

 

[JeffP1167]

here is the progress so far. It seems to fit pretty good and I am aware the rear section will need to be molded to match the original hood contour as well as other areas.

So let the tips start as to what my next steps are on getting this scoop bonded in and looking good!

 

[JeffP1167]

How sad is it that the POS hood I bought was much weaker then my orinal hood with all this material removed from it. You can see why I chose to never install the POS hood on my car. I actually fear it could seperate at road speed and damage other cars or hurt someone in the process.

 

[BBShark]

Is the back of the hood rough? It's amost surely fiberglass. I don't think there are any SMC long L-88 hoods out there.

Probably a good idea to use bonding strips at the joint underneath.

 

[pcf_mark]

+2 on the bonding strips. Scrap pieces will do but glue them on or the joint will "work" and show through. Your doing a great job fitting it together.

 

[mrvette]

+2 on the bonding strips. Scrap pieces will do but glue them on or the joint will "work" and show through. Your doing a great job fitting it together.

What IS a bonding strip??

 

[pcf_mark]

Technically a bonding strip is any rigid fiberglass material you glue to the back of a joint. Your car has them all over the place. If you reach in the front fender there is a molded fiberglass piece under the joint where the fender is glued to the hood surround. In this example I would use a piece of the old hood scrap cut into a strip to leave 1" on each side of the joint. Glue it on the bottom side with panel adhesive. Then grind the front side in a v about 3" wide total and fill with fiberglass matt/resin. The bonded joint supports the panels and prevents the joint from flexing and spitting along the seem.

 

[JeffP1167]

I have plenty of scrap SMC to make bonding strips so thats not a problem. Would I just use vette body panel adhesive to glue them to the underside of the stock hood and then when dry use more of this adhesive and bond the scoop to the strips? My goal here is while the stock hood is smooth underneath due to press molding the scoop is not like that and I would also like to get a smooth underside surface on it as well so the bottom of the hood can be repainted again.

I've seen quite a few youtube SMC repair videos of hole repairs using resin/mat/cloth and then finishing the surface repaired area with epoxy stuff to make the surface smooth again.

The original goal for this project was because I prefered the CFI air cleaner and serpentine drive from a 1984 vette over the stock 82 stuff. The stock hood had clearance issue with all this and I also planned on adding ducting under the L88 scoop to allow fresh air from the windshield into the air cleaner. I am also planning on adding C4 underhood lights to it & possibly thought about after its done make a mold of it..

That and the L88 hoods look awesome on this style of vette and the stock hoods are superior in fit and strength to ANY aftermarket hood.

 

[010752]

Here is how I would and I won't go into any reasons why:

Remount the original hood to the car and fit as nest you can.

Ductape the new part in spots to prevent slipping.

Grind a "v" into both parts all the way around. Have at least 1" ground on each part almost to nothing at the real seam. Use 20 grit discs, or as close to it as possible. No more than 40 grit.

Find some cabinet grade 3/8 plywood (more laminations) and screw and using it as a bonding strip on the bottom side, screw a few places to hold it.

Adjust the hood with spacers etc so the gap is even all along and just as important to get the up and down perfect with the fender contours.
Go along and place more screws in both pieces as you shim,. This is the most important part. If need be, you can even double up on the plywood if it is not firm enough. You want no flex now.

Do some final grinding etc and tape everything off that is not ground.

Final wipe with acetone, thinner or alcohol.

Use EPOXY, the reasons are for another book, no need to worry about it.
You can use mat or a finer cloth, whatever you are more comfortable with. If using mat, try getting the stuff without the styrene binder, but do a test first, if is stays milky when wetted thru, then it has too much. Personally, I would use cloth, it is easier to maintain the proper resin to glass ratio. Most pics you see of mat, is much too resin rich.

Cut all your glass for multiple layers and when ready have at it.
Keep adding layers, don't stop, until it is over flush. You can mix and match the cloth and mat.

If possible "post cure" it for 24 hours. (I used to use a kerosene salamander and would keep a bay up to 115°)

Now you can, remove the hood, screws, wood and "v" grind the underside of your joint. Grind as deep as you have to, just not all the way thru.

Same thing on the bottom as the top.

If you screwed up in spots on the top side, you can "v" them out again and redo, no need for the plywood this time.

If you want to strenghten the hood, you can glass in strips of glass, wood metal whatever.

When done this should look like an hood that has not been patched and to me should be stronger than a bonding strip job.

Good Luck.


BTW, your original hood is press molded and therefore smooth on the bottom, You scoop is probably hand laid or chopped and rough. You can either sand it now or later to make it smooth to paint.

 

[JeffP1167]

This is the piece I will have to graft into the back inner frame to support th back of the L88 scoop. Yet another challenge of doing this hood.

 

[MYBAD79]

Good advice from 010752 :thumbs:

Evercoat makes SMC adhesive that is good for SMC and fiberglass, it's the only product that I know of that comes in a can and does not require the dual cartridge mixing gun. All Duramix products that I found come in these cartridges. IMO a little pricey for a one time job...

Google "evrcoat smc adhesive" and you'll find it. This stuff is holding my flares on since 2006.

These guys are great: www.uscomposites.com

 

[JeffP1167]

I got incredibly burnt out on my 1990 project so today I drug the 1982's hood out and started working on it again. I almost have the scoop trimmed enough for fiberglassing it on now. My plan is this, since I removed some onf the original hood skin from the inner skin where this L-88 scoop will lay, thought I would just use vette panel adhesive to semi bond it in place and since this would be strong enough I wouldn't have to worry about the scoop moving while trying to fiberglass.

Also thought I would bond some scrap pieces to the underside of the original skin and the scoop to keep the fiberglass level and eliminate a lot of filling. I am not sure if I will ever put the hood on the 82 much less finish the 82 project but either way it's yet another learning project for me and might be for sale when done or maybe even make a mold of it.

 

[JeffP1167]

Well, I did my final trimming today on the scoop. My plan is this, I am going to lay down vette panel adhesive or some resin and mat to four corners of the inner hood frame, then run some small screws through the scoop and into the inner frame. This will creat a good bond so the scoop doesn't move around while glassing it in place as well as create an adjustment to get the scoop level with the skin of the original hood. After it sets then I am going to take scrap glass and bond it underneath and use clamps to also get the two piece as close to flush as possible.

After the surface glassing is done then I plan on adding a few extra layers of glass to the inside of the scoop as well as fab some reinforcement bracing to really stregthen the scoop so it doesn't vibrate or sag over time. I am also planning on smothing out the bottom of the scoop so it all looks press molded like the original underside of the factory hood.

I had once planned on adding ducting under the hood to mate with the 1984 crossfire air cleaner that is on this 82 so it draws from the base of the windshield. I've never liked the aftermarket hoods for their huge gaps and no side walls on the edge of the hood where it meets the fenders. So when done it should be as strong as a factory hood and fit like one.

 

[JeffP1167]

I finally finished all the trimming work on this scoop and temporarily pop riveted it in place for alignment while fiberglassing it in place. Still have to get the sides at the same level before fiber glassing begins, when it's done it should be strong and give me clearance under the hood and give the car better looks and perfect fender gaps.

I have a few mods I want to add to this hood as well. I'de like to add C4 underhood lights, gas lift hood supports instead of the original setup, mold a center inner brace to help support the center of the hood scoop,