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Plymouth Arrow Hood Modification

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  • Plymouth Arrow Hood Modification

    One of my former classmates from high school caught up with me a few months back, and had some work he wanted done on a hood for his Tubbed V8 Plymouth Arrow. Still has the same car from HS almost 4 decades later.. He said he wanted a more professional job over what was done back then..

    He had bought an NOS hood for it some years back, so at least he has something solid to work with.. He said the metal flopped a bit around the opening he cut, so I thought we'd add a wire edge around the opening and make some new bracing on the underside while we were at it. Here's the phenolic dies made for the Lennox to form the new bracing..

    Here's a test sample run...

    ...and a test fit

    Next, the bracing we wanted to install needed to go around the bigass hole, and some of the existing brace needed removing.

    Our new brace designed to go around the hole... cut in the flat and run through our dies..

    And here's about where it will sit....

    Last edited by MP&C; 23-01-20, 08:40 PM.

  • #2
    Rather than screw up one of the last remaining NOS Plymouth Arrow hoods in existence, let's do a test sample first.. To strengthen the opening, we'll add a 1/8 wire edge protruding upward, which will also help to keep things out.....somewhat. Here's our new dies for the 1/8 wire... This is the "inlet" side...

    Side view shows the ramps that will add the joggle

    We're using a 22 x 22 piece of 19 gauge for our sample, and folding a 5/16 flange, which needs a bit of stretching to keep things flat. so a rounded hammer on the top of the stump adds a bit of stretch, then a linear stretch hammer and dolly to stretch further and fold things over..

    with the flange folded, the sample is run through our dies to form the joggle

    1/8 stainless is rolled in our tubing bender/straightener, sized, and TIG welded to form a continuous ring. Then it gets laid in the channel and the flange staked over in various spots to hold it in place using the linear stretch hammer..

    Hammering process to fold the flange over. Linear stretch hammer used to add a bit more stretch and to minimize marks left behind..

    Finished sample...

    ….and checked to the brace

    Last edited by MP&C; 23-01-20, 08:41 PM.


    • #3
      With the practice behind us, lets see what we can do to this hood. The outer circle is the mark for our fold, or opening size. The inner circle is the cut for our flange that will wrap around the 1/8 wire..

      Getting our tin snips started...

      Hole cut with no filing, no sanding, and absolutely no metal "splinters".

      If you have issues with tin snips AT ALL, I recommend Bill Gibson's tin snip video... One of the best training/refresher videos on tin snips..

      Next, on to the underside. We have four places where these areas of the old structure was cut out that need to go. Opening the hood to see these remnants would just kill the look, so let's see if we can mimic a factory look here.

      A piece of 16 gauge was used as a heat shield and using the Meco torch and the barrel end hammer, reshaped the offset back to match the adjacent contour...

      That'll do pig, that'll do.

      Last edited by MP&C; 23-01-20, 08:42 PM.


      • #4
        I really like this project, Robert. Thanks for the pics and links, especially ones showing the your Lennox tooling details. Much appreciated.


        • #5
          Nice work Robert.

          That jiggly machine works really well!

          Cheers Charlie


          • #6
            thank you for sharing Robert, always nice to see what people are working on, class job as usual
            thanks neil


            • #7
              Thanks for the comments fellas!


              • #8
                With the hole cut now we need to fold a flange to wrap around the 1/8 wire. The linear stretch hammer and a heel dolly is used to stretch the flange that will be folded down, then a tipping tool takes the flange down about halfway. Then I needed to get in the thick of things, further stretching and hammering over to a 90* flange, all while checking the crown around the hole to ensure consistent stretch of the flange.

                Once the flange is folded, the Lennox is used to add the joggle for our wired edge..


                Bottom side....

                Top side....

                Our 1/8 stainless wire "ring" was formed using our tubing roller, the tool shown here in the vise when we were bending fuel line a few months back....

                The ring was then sized to fit, ends TIG welded together, filed, and media blasted for paint adhesion. The channel and surrounding area was abraded with some 120 grit and some SPI epoxy brushed into the channel. The wire gets laid into the channel and another brush coat on any bare spots. Then the flange is staked down using the linear stretch hammer to hold the wire in position...

                Then the flange is hammered over as we did previously with our test sample.

                After our initial coat of primer had dried, we brushed around the perimeter to seal the wire and flange.

                Next will be adding our new structural member to the bottom side.

                Last edited by MP&C; 24-01-20, 01:39 PM.


                • #9
                  Looking at the bottom side of the hood, all of the structure uses a radius where the parts intersect, so we may as well follow suit.. Holes were cut in some 19 Gauge and corners cut out..

                  Corners TIG welded and welds dressed..

                  The area our brace will cover is abraded so we can get it covered with epoxy primer before installing the brace.

                  Brace is media blasted to prep for epoxy primer, and test fit to the hood.. Once the epoxy sets up a couple days we'll get the brace welded in..

                  Here are some older pictures of the car just to show what we're working on...


                  • #10
                    Looks good, Robert. I really like the work incorporating the new brace to make it look OEM.

                    Nice to see the old pics with the simple hole in hood. I wondered if there was a scoop involved or not. It's always great to see a car survive the owner's youth.


                    • #11
                      Nice work thanks for posting, I always learn something from your posts. Can you post a picture of your linear stretching hammer?


                      • #12
                        It is shown in the YouTube video in the second post.


                        • #13
                          Excellent job of it Robert.
                          What kind of goop will you use between the hood and the brace?


                          • #14
                            great attention to the details robert, thank you for sharing your work
                            thanks neil


                            • #15
                              Originally posted by 123pugsy View Post
                              Excellent job of it Robert.
                              What kind of goop will you use between the hood and the brace?
                              Pugsy, 3M NVM dampening material, PN 04274. Supposed to stay pliable to allow hood skin movement. It needs the special gun to dispense and costs in the neighborhood of $50 +/- depending on where you get it.

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