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Finley Atherton

Well Known Member
How are people spacing their camlocs to attach the cowl to the firewall? I have the Milspec Firewall Kit for the 9A with 30 camlocks. As I figure it:
6 camlocs along the bottom of the lower cowl (3 each side) which gives a spacing of about 5.5?
10 camlocs for the sides of the lower cowl (5 each side) which gives a spacing of about 3.6?
14 camlocks for the top cowl which gives a spacing of about 3.8? to 3.9?

Finley Atherton 9A
 
That's the kind of spacing I have. The only change is I have 4 along each side on the bottom. I was told anything less than 4" spacing on the sides and should should be good.
 
Spacing

My neighbor has an 8 with 4" spacing. He gets some puckering at high speed. He recommended a 3.5" spacing. That is what I used and have no puckering.

I used a total of 4 on the bottom on my 7. And there are 9 on the cowl seam line.

These things are great and well worth the extra work and cost.
 
By the time I decided to go with camlocs, I had already drilled for hinges. I'm just going to drill out the hinges from the firewall and fill the holes in the cowl. Should be no big deal.

Then I started to think that maybe I'll keep hinges for the lower sides. Those are really easy to install/remove. The hinges along the top are the ones I really don't want to deal with and I hear the hinges along the bottom break, so I'll still install camlocs in those two spots.

Sound reasonable? Or would that look too weird with no camlocs along the lower sides?
 
Davepar said:
By the time I decided to go with camlocs, I had already drilled for hinges. I'm just going to drill out the hinges from the firewall and fill the holes in the cowl. Should be no big deal.
Click to expand...

When you fill these, I recommend a couple of layers of glass on the bottom side - makes it easy to fill the holes. Also helps slightly increasing the cowl thickness to prevent the camlock holes from growing over time.

You should probably wait for this step until you know if you'll need to trim off some of the honeycomb for the camlocks. It was a bit too wide in a few places when I fit my cowl.
 
Davepar said:
Then I started to think that maybe I'll keep hinges for the lower sides. Those are really easy to install/remove. The hinges along the top are the ones I really don't want to deal with and I hear the hinges along the bottom break, so I'll still install camlocs in those two spots.

Sound reasonable? Or would that look too weird with no camlocs along the lower sides?
Click to expand...

As long as you are using the hinges on the side of the cowls, fore to aft, I think using the camlocs just on the top cowl at the firewall would look great.
 
I'm curious about this spacing thing -- looks like what's recommended is less than 4".. On the other hand, I've seen now several production planes that have only a few camlocks, and they're spaced a lot more than 4 inches apart... What's the difference?

Eg. Cirrus has only 4 camlocks on the horizontal line joining two cowl halves (ok 5, if we count one that's on the firewall perimeter). Spacing is more like 10"... how come it works for them?
 
From reading some of the replies, I get the feeling that 4 camlocs along the bottom of the lower cowl on each side would be better than 3. Also I would like to have the spacing along the top cowl at about 3.5? which would mean that I need 15 camlocs for the top cowl.
So, all up the Firewall kit should really have 33 camlocks instead of 30:
8 along the bottom of the lower cowl (4 each side)
10 along the sides of the lower cowl (5 each side)
15 along the top cowl.
Maybe I might order an extra 3 camlocks????

Finley Atherton 9A
 
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Proof is in the pudding

Finley,
I used the spacing as you calculated it and as you can see from the pic below, it works.
That is:
6 camlocs along the bottom
10 camlocs for the sides
14 camlocks for the top cowl.

Maybe 15 on the top as this is where any puckering would be seen.

I also used a Cam Loc on each of the intake cheek to avoid those nasty little three screws which I have seen people struggling with. I would definitely do that again.

The Carbinge on the side provides a more aesthetic retainer.

It all stayed on to 221KT IAS in the flight testing
Pete.
 
If your upper cowl rests in place nicely, the spacing can be 3-4" without a problem. Where you have to watch closely..is up and around the firewall. This is the area that can pucker a little due to differences in how people choose to fabricate the flange and the camloc pulling down hard. I know my instructions said to add a shim on the flange at each receptacle along the firewall. I think this helps reduce the pucker by keeping the area around the camloc from dipping down in relationship to the rest of the cowling.(I hinged the bottom cowl at the firewall) I used 6 total at the bottom without a problem.

I made my own flanges from .050 and then riveted/bonded them to the lower cowl. Towards the front of the cowl, I formed them to a slight curve. The cowl sat down nicely. The flange on the firewall was two .050 strips runing from the center - down the left..and the right.

There's lots of ways to do it. Think it through and always consider the heat andflexibility down the
P8020033.JPG


http://experimentalrv7.com
 
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Camloc spacing

I used 3.5" spacing for mine. I agree that sticking with hinges for the sides works fine/looks fine. I went with 3.5" spacing to minimize the "pucker" as per recommendations of some of the other 50 or so odd RV'ers on the field. I bonded an aluminum strip on the upper edge of the lower cowling to install the receptacles.
 
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