Hood Vent Installation

Article by: Ed Holnagel

If you have been wheelin' Jeeps for very long you know that under hood temperatures can climb quickly to a point where it is almost too hot to open the hood. Under hood temperatures can soar when you are barely moving and the outside temperatures are pushing higher and higher.

After several summers of watching as the temperature gauge climbed and having my stock plastic radiator crack I decided it was time to do something to help vent the engine compartment. A vented hood such as the one made by AEV-Conversions is a great way to do this if you have an extra $700 sitting around, and that isn't for a painted hood, plan on at least $1000 to put one of these hoods on your Jeep. Having just shelled out the bucks for a new long arm lift, SYE and all that goes along with that, my budget was on it's last leg.

I then came across an idea on the web to use existing hood vents that were installed on 1994-1996 Pontiac Grand Prix GTPs. These vents can be bought new online for around $85 a set before shipping. If you want the internal drip trays then plan on $120/set. I however managed to find a used set including the drip trays on Ebay for around $45 to my door. They did require a lot of sanding and painting to get them looking half way decent.

It is a good idea to layout both vents at the same time so that you can check and transfer measurements from one side to the other and confirm that both are positioned correctly.

Installation began by making templates for both vents out of cardboard. After the templates were ready, blue painters tape was laid down on the area of the hood where the holes would have to be cut. A line was then drawn at 20 3/4" from the rear of the hood on the blue tape. Don't go any less than this or you will run into the bracing on the under side of the hood. A rule was then aligned with the seam in the cowling and lines were drawn along the side of where the template would lay. (see 2nd picture to right.)

The front edge of the template was then placed on the forward line. A strip of metal 3/4" wide was then layed on the inner edge of the template to set it's distance from the point where the hood starts to curve upward in the middle. The metal strip should lay flat on the hood at just the point where it would start to ride up the curve. You could also use a pair of nickels as they measure 7/8" instead of the metal strip if you don't have anything of that width laying around.

Once you have your templates in place take measurements from the back of the hood to the rear edge of the template on both sides to see that they are the same. The distance from the side marks to the sides of the template were roughly 1 3/8" at the rear mark and 1 1/2" towards the front. This may vary depending on how you lay out the template and there is no real wrong way to do it as long as you make sure that it is the same on both sides of the hood.

Tape the templates in place and trace the INSIDE of the template ONLY. Also mark the location of the holes to be drilled for the alignment pins and screw studs on the underneath side of the vents. Before removing the templates I laid the vents on top of them on their respective side and stood back to see that all looked right before I started cutting. Once you drill holes and start to cut there is no going back so make sure everything looks right before you pass that point of no return.

Using an air powered body saw like the one below that I purchased from Harbor Freight Tools for $19.99 plus shipping I proceeded to cut out the holes for the vents.

The blades on most of these types of saws are fairly short so you shouldn't have to worry too much about hitting anything under the hood. Don't worry if you don't cut right up to the lines, you can clean up the cuts afterward with a die grinder or some tin snips which is what I chose to use.

Once the holes are cleaned up you can remove the tape and test fit your vents. I have read where others have used 3M brand molding tape to stick the vents to the hood, however after applying the tape it became clear that it would hold the vents up off of the hood by the thickness of the tape which is about 1/16". As I wanted the vents to lay flat to the surface I chose not to go this route.

My initial idea was to use 12 small springs which I would place over each of the screw studs on the underside of the hood. Putting a small washer on a sheet metal screw and then through the spring I would screw the vents in place from underneath the hood. However, since my vents had been used the studs were no longer strong enough to hold the screws. If you choose to buy new vents then this technique should work great.

Instead I ended up masking around the vents to help keep the silicone off of the hood and then using black RTV silicone adhesive to glue them to the hood. A towel was laid over the vents to protect them and then weight was applied for about 3 hours. I then removed the weight and the masking tape and cleaned up any little bit of silicone that was left on the hood. The silicone should cure for 24 hours to achieve full cure, check the tube for more specific information.

I have to say that I have never been real good at "body work" but this project worked out fairly well and is good looking as well as very functional. If there was anything that I learned from this it is that if I had to do it over again I would probably go with new vents and forget about the drip trays as I don't think I will ever use them. The drip trays cut the effectiveness of the vents to almost nothing so to use them really is going against what this is all about.

So there you have it, the finished install.

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