Molding/Installing cowl hood?

I putting a 4" cowl on my '68 Galaxie, the hood will have to be cut so the air filter will fit up inside. I am going to put a cowl over is what is the best way to conect the two and do you just use bondo to mold them together?

Oh and the cowl is made of fiberglass picked it up at a swap meet for $40 yesterday.

I'd rivet or screw then together and them mold them flush using fiberglass. TSC has the best knowledge with glass.

The problem here is the two parts have different expansion rates. The glass part will expand more from heat then the steel part and all of the hard work you put into smoothing the joint will crack. It won't take that long either.
Using glass or bondo will not last. The best item I have used, which lasted for quite a few years, was an industrial adhesive from 3M. It's a two part epoxy. I bonded a glass cowl scoop to a steel hood and 90% of the joint was still servicable after ten years. You may want to look into one of the panel adhesives that are now available. These will not stop the joint deterioration but they will make it last for a much longer time. Good Luck
Mark

^Did you still rivet or screw the two together? And the epoxy is moldable I guess? Easy to use and were could I get some info on this stuff?
Thanks.

does your cowl still have its mounting flange? if so cut the hole in your hood just big enough to mount the cowl from under the hood, and use the epoxy to glue the flange to the bottom of your hood. then when thats dry, run a bead of the epoxy along the seam on the top side of the hood to give it a molded look.

^Thanks for the info, but what about under the hood how would that look?

well you could mold it like the top and paint it, that should look good

You'll see a ton of bracing on the bottom side of your hood. Cutting all of that away to mold the scoop on from the bottom will cause a lot of flexing when you open and close the hood. The flexing will stress the joint and it will not last. If you need a hole for carb clearance I would recommend removing only the area you need for the aircleaner. This leaves your hood with all of it's bracing and you don't need to worry about cleaning up and finishing a huge seam on the bottom side.
I will suggest getting a glass hood. I know it costs more then forty bucks but you are going to have a lot of time and material costs in adding this scoop to your stock hood and it will not last. It's something you will be chasing forever. Get a glass hood, paint it once and stick the original hood in the rafters...
Mark

if not done correctly, my friend did my way to hi Lightning and he hasnt had any problems. and its been over a year...

I like both the ideas, but I won't cut a hole any bigger than I need I just don't think it will be strong enough. And getting a hole glass hood is a bit costly I just don't have that kind of money, And I have never seen a hole glass hood for a '68 Galaxie either I haven't even seen a hole hood in fact.

hell, if you reall want to, do both ideas... do mine, then epoxy the bracing back over the opening to make it nice and strong...