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Thread: Metal Vents 101

  1. #1
    Senior Member Don's Avatar
    Join Date
    Oct 2002
    Victoria, BC Canada

    Metal Vents 101

    OK; I promised everyone I would show how I built the fender vents. This process can be transferred to any of the vents that we all have on all of our projects. I plan to use the same process on my Countach vents as well.


    • Riv-nuts or nut-serts (whatever you call them).
      • You can use any size but I chose #8 as I they are small enough to be less conspicuous but still big enough to hold

    • 16 gauge aluminum sheet
      • I got a big sheet but you can also get strips if that is easier. I have a bandsaw so I was able to cut my fins out and then file to shape so whatever you use with the tools you have at hand

    • Bastard Rasp and finishing file and 180 grit sandpaper and block
    • patience.... lot's of it as there are lots of fit and file, fit and file etc.....

    1. Step 1: Make a template of the opening for the side plates.
      1. I used some laminate I had laying around but you can use cardboard as well.
      2. Place the template material up against the opening sides and trace out your shapes.

    2. Step 2: Transfer template to aluminum
      1. Cut the aluminum side plates out and use the bastard rasp and finishing file to make to shape of the template
      2. Fit to the opening several times during the filing to make sure the side plates are conforming to the opening shape
      3. Once the side plates are to your satisfaction, take the 180 sanding block and sand both sides and all edges to get a nice finish

    3. Step 3: Mark the fin placements on the side plates
      1. I used 1" between fins on my setup but you decide the spacing that suits your opening
      2. I also used 45* angle but that is also what I set in place for the rear opening wall so it all looks symmetrical
      3. I used a metal scribe on the aluminum so that I had a good reference line. Pencil will rub off and indelible marker just makes a mess.
      4. My side plates ended up with 11 fins
      5. Mark the mounting holes and drill those out
      6. First picture shows the templates and side plates I made for mine.

    4. Step 4: Cut the fin placement slots into the side plates
      1. Measure the distance down from the top that you want your fin slots to be
      2. I used a 1/2" fin tab so I measured down 3/4" from the top of the side plates and marked the top of the slots
      3. I then used my band saw to cut up from the bottom of the side plates to make my fin slots
      4. The reason I used the measurements from the top was to get a consistent length all along the side plate.
      5. The top and the bottom of the side plates may not end up exactly the same width along its length so use a common reference point.
      6. I chose top as that was the edge I paid attention to when making the side plates.
      7. The length of the slots will be determined by you and the side of the fins. You don't need a huge tab but you want one large enough to make sure it holds the fin in place when you are doing your soldering/welding later
      8. The second picture shows the side plates with the slots cut in

    5. Step 5: Install Rivnuts into opening
      1. Place the side plates back into the opening and mark the mounting holes
      2. I drilled the mounting holes for one mount on each side and then installed the riv-nuts and finished the other two each side afterward so I had a solid reference for the final placement
      3. Drill out for the riv-nuts
      4. I also inset the riv-nut heads for a flush mount of the vent sides. Your preference for what you want to do
      5. Third picture shows the riv-nuts in my first opening.

    6. Step 6: Make template for the fins.
      1. I used a metal template for my fins.
      2. I placed the metal piece up against my rear opening wall and traced and then cut the template to size
      3. Fourth picture shows the two templates I made

    7. Step 7: Make Fins
      1. I traced the fins out on my aluminum sheet and used my band-saw to rough cut the fins out of the sheet.
      2. I needed 11 per side so I cut out 12 to have a spare. (I needed the spare on both sides...... )

    8. Step 8: Finish the fins
      1. I deburred the fins from the rough cutting and placed all rough cut fins together and placed the metal template on one side of the fins.
      2. From there I clamped the fins and template together and put it all into the vice
      3. From here, you use the bastard rasp and finishing file to clean the shape of all the fins to the template.
      4. Time consuming but the fins turn out very nicely
      5. Fifth picture shows the finished fins clamped to the template for reference

    Out of pictures upload capability so next post will continue the process

    Attached Images Attached Images      
    Last edited by Don; 07-27-2014 at 12:03 PM.
    308 Ferrari replica
    Prova Countach 5000QV

  2. #2
    Senior Member Don's Avatar
    Join Date
    Oct 2002
    Victoria, BC Canada
    1. Step 9" Make the fin tabs
      1. I made the one side tabs on each fin so that I had a reference point for placing the fins into the side plates.
      2. I marked each fin on the back side 1 to 11
      3. First picture shows a finished fin but I started with one side and then cut in the second side as I placed the fins in to the opening

    2. Step 10: Fit the fin to the opening
      1. I mounted the side tabs into the opening so I had a clear picture of the fin width requirements
      2. My openings are not 100% accurate as most fiberglassing will end up being so the fins needed to be fit for each slot
      3. Once the tab was made, I went to the opening and placed the finished fin side into the opening at the bottom edge of the side plates
      4. I marked the other side of the fin where it came in contact with the other side plate
      5. I then cut the fin to the mark with the right angle and tab on the opposite end
      6. This is where the tedious part comes in.
      7. Fit the fin back in to the opening, see if it fits
      8. Mark where it is still off a bit
      9. File the side needed
      10. Refit, file , refit, file and repeat until the fin fits in its slot snug but not applying any undo pressure against the side plates
      11. Rinse and repeat until you have all fins cut and fit into the vent opening
      12. Second picture shows the fin placing in the opening
      13. Third pictures shows a completed fin pushed up into place

    3. Step 11: Mark an alignment reference line on each side plate
      1. I used this line to line up my side plates when setting up for soldering
      2. My fins are at an angle so I needed to make sure the side plates were aligned once everything was pulled out of the opening to solder/weld together
      3. Fourth picture shows the mark being put in place

    4. I also added a fifth picture to show another view of the fins all together getting filed to shape.

    I am now at the point of soldering the driver's side so I will take some pictures today of the soldering process and post more later.

    Attached Images Attached Images      
    308 Ferrari replica
    Prova Countach 5000QV

  3. #3
    Senior Member RCR's Avatar
    Join Date
    Jan 2002
    Shelby Twp Mi
    Good stuff, Don.
    Bob custom '84 Fiero SE --->>> custom F408

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