I am using a hood that had heavy corrosion in the seams. the owner gave it to me after I painted and installed his new one. so I had nothing to loose if I messed up. I am cutting the hole in the hood without ever bolting it on the car. I didn't do it exactly as I am describing here. I cut the hole 4 times to finally get it right. the dimentions I am giving hopefully you will only have to cut once.
to start I measured a 13 GT500 hood vent from the rear corner of the hood to the upper corners of the vent on the L & R side. then did the same to the other side.
I then drew a curve for each corner from the hood corner to locate the vent.
I lost this pic when I changed computers.
next I placed the vent in the center of my X I made from my measurements and traced the scoop on the hood.
you can see the X in the bottom of the pic.
the scoop has a stud in the center to hold it on. as seen in this pic.
there are 2 tabs on the scoops. remove with a side cutter you don't need
them. if you look closely at the pic you can see the leftover tabs.
drill a 1/8" hole in the center line of the hood, this is where the stud go into to locate the scoop for better tracing.
once you have the vent located wipe off your rough tracing marks and make some more accurate ones now that the vent will lay tight against the hood.
now that you have accurate tracings lay a 3/4" tape line below the top line and taper the side lines from 3/4" to 1/2" on the bottom line.
I didn't do it like I described above. I made a smaller cut then made a more accurate one once I hade a better idea on how it fit.
my rough cut about 1" away from my trace lines. the masking tape is 3/4 for size reference.
now a more accurate one. the blue fine line is 1/2".
you will have to trim the braces on the back side larger than your cuts on the top. it will help to prevent cutting the top side of the hood by sliding a small piece of steel between the braces and the hood.
here is the bottom of the hood braces after trimming.
the bottom of the vent has 3 tabs molded into the channel as seen in this pic. you will have to cut slots for them in the hood to allow the vent to slide in. if you look closely you can see a cut in the bottom for the tab.
once you have cleaned the edges of your cuts it will now just slide in.
when I do this next time I will move the vent about 2" higher in the hood. it's a little to far foreword in the hood. it is 3/4 of the vent directly over the radiator. also 12 and up GT500 hood the area where the vent is located is raised. it lightly hit my heat exchanger tank. I had to lower the sway bar cross member 1/4" and move the tank about 1" towards the engine for clearance. be careful how far you move the hole back. the fuse box is located on the passenger side of the hole about 1" back.
I think if you have stock plastic tanks everything should clear without mods.
the vent slides right in. you have to apply 2 sided tape around the outside edge to help hold it tight to the hood. if you put a nut on the stud in the earlier pic the vent can't fly off. it's held on by the lower groove and the stud.
on the 12 and up hoods the area where the vent goes is recessed to allow a flush fit. on your hood you won't have that so your vent will be on top of the hood.
hopefully tomorrow I will post a pic of the finished hood installed on the car.
the whole process there was a LOT of cutting. here is a pic of the waste aluminum on the floor.
