Firewall Forward

February 1, 2013

Oil Pressure Hose; Cotter Pins on Engine Mount; Trial Fit of Exhaust - 2.0 Hours

As we begin a new month, I'm continuing some details as I learn bit-by-bit a little more about my engine and everything that goes on it. Plus, I'm working with items I have on hand. My budget hasn't allowed me to just go purchase a Firewall Forward Kit from Vans. I'm buying it piecemeal as I go, a little at a time, as my budget will allow. This is a bit more of a hassle, but I really don't have any choice so I'm making the best of it. I'm close to Vans, so it's easy enough to go over there, talk with the guys, and bring home a few parts at a time.

Also, as a newbie to airplane ownership and firewall forward and engines and all, I'm learning as I go. So it's painfully slow, as each little item that I work with is new to me. So I feel like in order to do a decent job and make sure things are done right, I should read up and study and see how others have done a certain task before I tackle it myself. I don't want to just slam this all together. I want a thorough understanding of each thing, how it works, how it goes together, why it's there, and so on. So this is a big learn-as-you-go time for me during this phase of the project. I still have that feeling of a newly weaned baby, since there are no clearly written step-by-step directions to follow from now on. So I don't expect to be as fast as someone more experienced than me, or someone who has owned an aircraft before.

So what did I tackle next? Well, the oil pressure hose and connections have been on my mind, and I have the hose and fittings here from Vans, so I went ahead and put it together. The hose connects to the transducer manifold on the firewall with a 45° connector, on the middle fitting as seen below. A couple of adel clamps hold it in place across the top of the firewall recess.

The other end connects to a 45° restrictor fitting threaded into the accessory case on the rear of the engine, near the engine mount, near the right magneto. If you're following my log, you'll recall that I installed this fitting back on November 12th and checked to make sure it was at the correct angle so the hose wouldn't rub on the magneto. I have a picture of it on that page. Well, fast forward to today, and I'm installing the hose now. Hopefully for good. Here it is, coming across the firewall, over the top of the mag, and installed on the fitting. I'll have my tech counselor look at this on a future visit, but for now, I'm calling it done and moving on. Feels good!

Next, ever since hanging the engine, I've had it on my mind to finish the job. Namely, torqueing the bolts, and inserting the cotter pins in the castle nuts. I've been worried a bit about how to do this, since it's tight in there, and the holes are at an angle, and I didn't know how I was even going to get a cotter pin in there, let alone some tools to bend the ends over. So I jumped in, figuring there must be a way to do it. The first thing I discovered was that I needed another washer under the castle nuts, to bring the nut out far enough on the bolt so that the cotter pin would be lodged down in one of the notches. I was worried a bit about loosening these nuts and bolts, after going to all the trouble to hang the engine. But if you just do one at a time, it's no concern at all. So one at a time, I carefully took off the nut, slipped another washer on, and then torqued the nuts down, making sure to get a notch in the nut lined up with the cotter pin hole in the bolt. Now to get a pin in the hole...

What I discovered was, if you have to, you can turn the whole bolt, nut and all, to orient it so you can get the cotter pin in place. Once it's in the hole, you can turn it some more so you can get some needle nose pliers in there to bend it over. The end of the cotter pin that points down is trimmed a bit. I bent the other end up over the top of each bolt. Here's a closeup of the final installation on the upper left mount.

Here's the upper right mount. This wasn't too bad either, now that I knew how to get it done. In fact, this cylinder has more clearance than the one on the other side, from the pushtube. But the lower ones had me concerned.

I fiddled around and found out that even the lower ones aren't that bad. The hardest part was finding a way to get comfortable working down there. Finding something to sit on. Just be patient and you'll get them in. Here's the lower left bolt, all finished.

And finally, here's the lower right one. This was a tight fit, with the oil filler tube right there and all, but I got 'er done.

With that behind me, I was excited about moving on, so I pulled my exhaust system out and decided to try it on for size. The guy I bought my engine from threw in this exhaust system, which I was really excited about! It would save me over a thousand dollars! So I wanted to check it out and at least do a trial installation at this time. He thought it was for an RV, and it looked good to me. So I got busy with it, pulled the covers off the exhaust ports on the engine, and started bolting it on, just finger tight for now. As you can see below, cylinders #1 and #3 on the right side went on without a hitch. Perfect fit!

This is a four-pipes-into-two system, so the #1 cylinder pipe joins up with #2 on the left side. This fit perfectly, too. You can see below how the pipes join in the middle in front of the sump. The tube from #3 is behind it, right in front of the sump, waiting to join up with #4.

Here's a shot of the #2 cylinder on the left side. Three out of four are on. Everything fits perfectly. Three down, one to go!

However, when I got to cylinder #4, things took a turn for the worse. The short tube that comes down from the exhaust port runs right smack into the motor mount. DANG IT! I spent time fiddling with it, examining all of it over and over a dozen times. I polished the end of the tube, as you can see, on my scotchbrite wheel, wondering if there was some way to rotate something and get it to fit. There's just no way. This system isn't going to work on my installation.

Well, that was a big disappointment. I don't know what kind of installation this system was designed for. Perhaps a taildragger. ??? The motor mount is quite different for the taildragger RV's, since the main gear legs come up at an angle and go into the motor mount, and of course, there's no nose wheel. The whole mount is different. I wish I knew someone in my area who was building one, so I could go take a look and see. I'd like to find out who can benefit from this system, so I can put it up for sale it and put the money toward the one I need. I'll give somebody a good deal if I can find out what this is for. I don't know where to begin. Somewhat discouraged, I called it a night.

UPDATE: I do have a friend in the area building an RV-7 taildragger, Trevor Conroy and his Dad, down at Aurora. And he recently installed his engine. So I made arrangements to meet Trevor at his hangar and bring my exhaust system along with me for a trial fit, before he installs his own exhaust system. I was hoping that if it fit, he might buy it from me at a good price, saving him some money and helping me out, too. So I was excited to put it on his plane and see if it might work. I was embarrassed when I pulled the bottom cover off of his #4 cylinder. His engine still had preservative oil in it, and it immediately ran out all over his floor. I put the cover plate back and tightened down the nuts as soon as I could to minimize the mess, and he wasn't worried about it. But I felt foolish, nonetheless. Bottom line was, it wasn't going to work anyway. I didn't need to pull the cover off to see that. I could slip the pipe on over the bolts, as seen in the photo above, without taking the cover plate off, and see clearly that it would not work. It hits the motor mount in a taildragger arrangement just like it does in mine, so it's a NO GO. Sad to say, now I really have no idea what this exhaust system will work on, or what it was designed for. Some day I hope to find out, and maybe get something out of it.

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