Friday, March 18, 2011
Fitting the Cowling Pt.1
1)I'm fitting a Sam James cowl to my 8. I'll be using Skybolt fasteners around the firewall and hinges on the sides. This may be the biggest challenge of the project as nothing fits from the start. Oh Joy! Slow and Steady is the key here... *Tip Start by marking the center of the forward top skin and fwd and aft top cowl. After trimming up the front inlets a bit(not the final fit), I worked on trimming the top cowl vertical attachment(firewall). Tip- Mark each metal ring at the top center and halfway points. This will help you determine the front horizontal trim for the top and bottom cowl pieces. You want a 13" spinner ring too. I trimmed about 1/4" off the front(left inlet to right inlet).
2)I hot glued a pair of wooden dowels to the top of the cowl to get the height right. The thickness of the hot glue,(about 1/8"), will cause the spinner to sit slightly high. I'm thinking this will even out if and when the engine sags. If you don't want to compensate for engine sag, I'd recommend using some metal shims/tabs and clecos. I'm also using some 3/16" spacers to set the distance from the spinner. It will need some work, as it is not parallel now.
3)After several hours of sanding and fitting, I have a good fit on the top rear cowl. I'm trimming very carefully with 80 grit paper. I will leave a 1/32 gap to prevent paint chipping before I'm done.
4)Initial look at the bottom cowl. It's going to take a lot of work, but I'm up for it!
5)Some progress.... The skybolt top mounting plates(2) have been drilled,deburred,countersunk,notched,prosealed, and clecoed into place. I will rivet the two pieces, to the firewall, after the proseal has dried. I used a dremel tool with a cutting disc and a rotary file to cut the notches. I also made the right strip 2" longer(on the top side) than the left. This is done to add support to the fwd baggage door side(firewall).