Cowl Paranoia

[pvalovich]

I'm fitting the upper cowl of my -8A (Skybolt fasteners) and have encountered an issue that's driving me nuts. I can align the cowl horizantally with the horizantal midpoint of the firewall AND SIMULTANEOSLY align the cowl symetrically with the spinner plate AND SIMULTANEOUSLY get a uniform 3/16" clearance between the cowl and spinner plate.

But in doing so, the lower right aft edge of the colw sets about an inch further aft of the firewakk than the left aft lower edge - implying that perhaps something (firewall, engine mount, engine, cowl, cowl aft edge, spiner plate) is misaligned - or in the case of the cowl, manufactured with non symmetrical edges.

However, everything checks out when carefully measured.

Do I continue to search for an alignment glitch - and figure out a God knows what fix - or declare cowl fitting victory and make the cut?

Anyone encountered a similar issue?

[alpinelakespilot2000]

This is very common. In fitting the cowl you have to be prepared to modify it to fit. In this case, it sounds like you might need to build it up around the spinner opening. Remember also, however, that if you expect any future engine sag, you don't really want a uniform 3/16" between spinner plate and cowl. Accordingly, leave that gap wider at the bottom than at the top. Hope this helps.

Edit--I think I misread your question a little, but the basic point still remains. Do what you need to do to get the cowl halves to fit each other first at the front and then with the fuselage at the firewall. Then, if necessary, you can build up the spinner opening to get the appropriate gap. Just trim a little at a time until things start lining up. It's a very iterative process. Good luck.

[pierre smith]

.....Paul. Remember that the engine mount is offset, pointing the engine to the right.....one reason the right side is further back than the left. Could also be made with a longer side but as long as you've aligned everything, you're good to go. Cut off the excess.

Regards,

[alpinelakespilot2000]

Originally Posted by pierre smith

.....Paul. Remember that the engine mount is offset, pointing the engine to the right.....one reason the right side is further back than the left. Could also be made with a longer side but as long as you've aligned everything, you're good to go. Cut off the excess.

Regards,

This was my first thought as well, Pierre. But isn't the engine offset to the left (when facing fwd)? I need to go home and check mine!

[pierre smith]

....what you mean, exactly but if you sit in the cockpit looking forward, the engine will be pointing a little to your right.

Regards