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  #1  
Old 08-07-2022, 06:33 PM
rockitdoc's Avatar
rockitdoc rockitdoc is offline
 
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Location: Fort Collins, CO
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Default Cowl Fitment

I started trying to get the cowl to fit in accordance with the plans today. Lots of on and off, sanding, on and off, sanding....

But, even with virtually no gap at the aft end of the cowl and firewall with everything centered left and right, the gap between the cowl and the spinner mount at the top (red arrow) is double the gap at the bottom (green arrow). But, the plans say this should be reversed, ie, bigger gap at the bottom so when the engine droops the gap evens out. I can't figure out why the gap is larger at the top or how to reverse the situation.

Any ideas appreciated. Oh, the spinner mount is square and flat.

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Emp Completed 11-12-20
Slo Fuse Completed 3-2-21
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  #2  
Old 08-07-2022, 06:42 PM
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Default

Been sitting here thinking about it ... can you post a pic of where the cowl meets the fuse? Perhaps side and top?

Also, can't tell from the pic, do you have the appropriate spacers (washers?) under your angle bracket?
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  #3  
Old 08-07-2022, 06:54 PM
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rockitdoc rockitdoc is offline
 
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Default

Quote:
Originally Posted by bkervaski View Post
Been sitting here thinking about it ... can you post a pic of where the cowl meets the fuse? Perhaps side and top?

Also, can't tell from the pic, do you have the appropriate spacers (washers?) under your angle bracket?
You bet.

Side View

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Top

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Washer/Spacer

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Plans indicates 1/32" washer. Too thin, perhaps?

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Emp Completed 11-12-20
Slo Fuse Completed 3-2-21
QB Wings 99% Complete 7-30-22
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  #4  
Old 08-07-2022, 07:32 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
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Default Cowl

Scott, sorry but you 14 builders are spoiled.
That's just a little Vans fabrication error on the nose bowl. The fit looks beautiful.
Mark the outside where you want it. Remove the cowl. Apply some flox or layers of fiberglass inside equal to the amount you need to remove on the outside. That way the finished thickness after sanding will be correct. Grind it down to the mark and move on.
You should have seen mine. That's pretty nice.
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I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.

Last edited by wirejock : 08-07-2022 at 07:35 PM.
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  #5  
Old 08-07-2022, 07:41 PM
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rockitdoc rockitdoc is offline
 
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Default

Quote:
Originally Posted by wirejock View Post
Scott, sorry but you 14 builders are spoiled.
That's just a little Vans fabrication error on the nose bowl. The fit looks beautiful.
Mark the outside where you want it. Remove the cowl. Apply some flox or layers of fiberglass inside equal to the amount you need to remove on the outside. That way the finished thickness after sanding will be correct. Grind it down to the mark and move on.
You should have seen mine. That's pretty nice.
Thanks Larry. I feel a lot better!
So, just adjust the glass in the front to get the tolerances called for. 3/16" at the bottom with less on top to account for sag after engine drops a bit.
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Emp Completed 11-12-20
Slo Fuse Completed 3-2-21
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  #6  
Old 08-07-2022, 08:34 PM
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Default Adjust

Quote:
Originally Posted by rockitdoc View Post
Thanks Larry. I feel a lot better!
So, just adjust the glass in the front to get the tolerances called for. 3/16" at the bottom with less on top to account for sag after engine drops a bit.
Unless other builders have a better solution. That cowl fit at the firewall is perfect.
You may want to install the bottom and treat them as a unit before modifying the top cowl. That way they match.
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Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog: http://wirejockrv7a.blogspot.com
Donated 12/2022, plus a little extra.
RV-7A #73391, N511RV reserved
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #7  
Old 08-07-2022, 08:47 PM
Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
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Default Rocketdoc: an option to consider

You can trim the lower rear of the cowl to drop the front and open the gap to the spinner. This will likely eliminate a lot of custom micro/flox work and preserve the molded periphery of the spinner area. If the cowl top cannot be lowered a little, you may have to fill and sand as wirejoc suggested.

Just put tape on fuse/boot cowl carefully corresponding to edge of the metal you want to mate nicely with the cowl rear edge. Position the cowl with spinner gapped as you wish (more gap at the bottom you said). With a compass or scribe set the width of the tape, scribe a line on the cowl a constant distance ( tape width ) from the BACK of the tape. Then sand to the line. After you install your fasteners, you can fine tune the cowl to fuse gap you desire with sanding block.
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  #8  
Old 08-07-2022, 08:59 PM
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Quote:
Originally Posted by Larry DeCamp View Post
You can trim the lower rear of the cowl to drop the front and open the gap to the spinner. This will likely eliminate a lot of custom micro/flox work and preserve the molded periphery of the spinner area. If the cowl top cannot be lowered a little, you may have to fill and sand as wirejoc suggested.

Just put tape on fuse/boot cowl carefully corresponding to edge of the metal you want to mate nicely with the cowl rear edge. Position the cowl with spinner gapped as you wish (more gap at the bottom you said). With a compass or scribe set the width of the tape, scribe a line on the cowl a constant distance ( tape width ) from the BACK of the tape. Then sand to the line. After you install your fasteners, you can fine tune the cowl to fuse gap you desire with sanding block.
Hmm. Since the top of the cowl is fixed with washer and angle, Iím not sure trimming the lower aft cowl does the trick. That would work if front of cowl could drop. But, I may not understand. Not unusual.
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  #9  
Old 08-08-2022, 05:24 AM
Larry DeCamp Larry DeCamp is offline
 
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Default Sag allowance ?

The washer makes a nice reference and aesthetically pleasing starting point. The wild card here is how much sag to anticipate and accommodate. Some folks say they get none and others inquire about mounts that don’t sag so much. The motor mount shim option is another tool you can use to optimize this cowl/spinner relationship.
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Last edited by Larry DeCamp : 08-08-2022 at 05:27 AM.
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  #10  
Old 08-08-2022, 05:57 AM
MED MED is offline
 
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Default

Be careful about having the cowling too tight at the fuselage joint. Remember to allow for paint thicknesses. You don’t want to damage it when you take it on and off and the edges hit. Just my experience.
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