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June 2004
So after I got my beautiful engine from Performance Engines, I wanted to begin right away with fitting the cowl. I imagined this being as hard as the canopy, but really, it was not so bad. I began by trimming the lower cowl joggle to about an inch. I used tape as a guide. I then started trimming the nose gear cut-out and was careful to tape the rough edges each time after cutting so I wouldn't scratch the gear strut. OK, so now it's starting to fit. At this point I used a water level to level the plane (with the canopy rail edge) and make reference marks.
Now for the fitting. I used a special jig I got from Jim Cohelo so I can make sure the lower cowl matches the spinner back plate (and fit in a manner to allow for the sagging the engine will experience. I fit the cowl 5/16" low). The most important number in using this jig is the distance from the hub to the spinner back plate, To get that, I measured off my propeller (three times). I then moved the adjustable dummy plate to the desired length and tightened it down. The lower cowl was clamped to the front with some hand clamps and I transferred a line so I knew how much to cut off the back. The transfer line was made by measuring from the fuselage step (for the cowl) and marking three inches aft. I then wrapped the blue masking tape for future reference. I then transferred marks three inches forward on the fitted lower cowl. Once the cowl was trimmed I kept pulling up on each side to get it to fit as tight as I could AND kept verifying it was even by referencing my level marks. Once there it was drilled and clecoed.
The bottom was easy. The top was a major pain. To fit, I took that cowl on and off over and over and over. This was the crucial one, so it took a good five hours to get to the cleco stage.
First off, The joggle in the front around the inlet just had to go. No way to make that work except make new ones. That's what I did. And the small area I did keep (needed for clecos) were sanded so much I had to put a three-bid lay-up from behind to replace what I took off. A thing that helped was to clamp my spinner back plate on to set the height of the cowl. I took off about 1/2" off the lower edge of the top cowl. That was surprising, but whatever it takes. The process can be described as sneaking up on your line. Just keep fitting and transferring the line. The joggle edge is very rough on the lower cowl, but with a release of either flox or micro and it will be nice. More bodywork (yippee!).
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