So the battery mount is set aside for a while. That left two more firewall tasks, one simple and one less so. The first was just drilling the two mount holes for the oil/fuel pressure manifold – that was easy enough. The second was finishing up the holes for the three control cable penetrations.

For these cables, I decided to go with steel eyeball-type mounts. These provide a nice sturdy seal, but also allow for some finessing of the angle at which the cable goes through firewall. The fun, though, is that each of these requires six screw holes around the perimeter, in addition to the actual passthrough hole. The eyeballs come with nice drill templates, but they assume that you’re starting from scratch – that is, you’d use the template to make the six screw holes as well as the center of the pass through, then drill them all. Well, I had two 1/2” prepunched holes, and one 1/8” one…so I couldn’t use the templates as provided.

After exercising a decent amount of brain power figuring out an approach for this, I hit upon a solution, which revolved around using the actual backer plate as a template. The first step was to open up the prepunched hole to just under 1 1/8” using a step drill, and then I could use that step drill bit to hole the backer in place, using the passthrough hole as a reference. Then I used a 5/64” drill bit to start a dimple through one screw hole, then finished that hole to 1/8”. That allowed me to put one screw in, plus the step drill for centering, and follow the same procedure for the other five screw holes.

This procedure worked out fairly well, except for one thing – using  step drill on the thin stainless steel doesn’t make for a really great hole. In fact, it tends to wrap the steel just around the hole, while also creating an enormous burr on the backside of the hole. I spent a pretty annoying amount of time reducing that burr to a manageable state, but in the end the hole still isn’t super clean.

I didn’t really like the idea of using this same approach on the other two holes, so I paused and did some research fro better ways to approach this. At some point, I realized that I had a much better tool for this – a knockout punch set I bought a while back. The only problem was figuring out where I’d put the thing…and I spent probably a solid hour hunting around the hangar (this time is not included in tonight’s logged build hours).

All that searching time paid off. One of the punches was the exact size I needed for the passthroughs, which was a nice bonus. I got the second and third holes punched, but stopped short of drilling the screw holes – I’ll leave that for another night. This photo shows how much nicer the punched holes (right and center) are compared to the drilled one (left):

There’s also one more bit of complexity, which my be visible above – the rightmost hole is really close to the firewall support angle, to the point that the punch took a small bite out of the angle. Because of this, the backer plate isn’t going to be able to sit flush against the firewall without some additional creativity. I have a plan, though – the angle piece is .063” thick, and I have plenty of .063” scrap, so I should be able to just fabricate a shim to go between the backer and the firewall; this will effectively make a full flat surface for the backer plate to rest on.

Tonight was just putting the finishing touches on this mount, or at least most of them. I wanted to get all the lightening holes cut, but I can’t “finish” finish it until I have the nutplates I’m missing, and I’m going to wait until I also know the mount bolts I need so I can combine Spruce orders.

I did spend some time thinking through the layout of the holes, and I ended up massaging the large hole behind the battery a bit, and then laying out just a few smaller holes in the area below the battery box. There wasn’t any room for useful holes anywhere else, at least while still leaving what I felt was enough material. Probably this thing is way beefier than it needs to be, but such is the nature of eyeball engineering – better safe than sorry.

Anyway, the large hole got cut with my hole cutter, but the smaller ones I did with a large step drill. The hole cutter is nice, but I don’t have quite the precise control over hole size that I get with the step drill. All that step drilling generated a pretty big pile of aluminum fuzz:

And here’s the mostly-finished mount:

So now I’ll set this aside and do the rest of the firewall stuff, which at this point is limited to the manifold mount holes and the eyeball passthroughs for the control cables. Hopefully by this weekend I’ll be hanging the engine…again…

Whew – it’s been a busy few days out here. We had evening events both Thursday and Friday, so no after-work shop time those days. Then I spent all day yesterday helping my brother move, and today was lots of housework, including finally giving in to the inevitable and mowing the grass. But I still made sure to squeeze in an hour for build stuff today.

Anyway, this evening’s work was just taking the previous session’s rough-cut edges of the mount and working them into their final lines, then cleaning all the edges up and making things nice and smooth. Not a lot to describe here, just repeated work with the Dremel cutter, then some filing to straighten out edges as needed, then smoothing with sanding discs. As usual, the old grooved flap wheel knocked off the burrs nicely.

So the outside edges are now done. Next up will be cutting some lightening holes, which should be relatively easy work – that’s just using the circle cutter, unlike this complex layout work.

For a photo op, I temporarily mounted the battery box plus the contactors, though now that I review this photo I see that it shows basically none of the actual mount:

At least I had the smarts to flip the thing over and get a pic of the backside too, which actually shows off tonight’s work:

The one “20/20 hindsight” thought I’m having is that I probably would have been better off avoiding all those fancy concave cutouts between/around the mounting holes. It would have saved a lot of manual finishing work, and I probably could have saved just as much weight by way of additional/larger lightening holes. Oh well, that ship has sailed now.

So…let’s start with the fun part. Tonight I actually started over from scratch with the battery mount. I guess it’s a good thing I bought two pieces of .063 for this work. Basically, the problem I ran into was that my late-breaking idea to put spacers between the mount and the firewall caused other issues.

The first thing is that this pushes the mount closer to the lower engine mount tube, increasing the chance that the battery box might interfere…and I can’t easily verify this without remounting the engine (again). This problem is compounded by the decision to use bolts to attach the box to the mount – originally I had the box sitting pretty close to the contactors, but this layout would cause the starter contractor to interfere with the attach bolt for the box. Fixing this would require moving the box lower – which would again increase the chances of interfering with the engine mount tube.

With that in mind, I decided to change things up a bit. Instead of putting the contactors above the battery box, I’ll put them below it. This pushes the battery box higher, providing more leeway between the box and engine mount. It’ll also allow for some nicer routing of other cables – I’m going to move the ANL fuse holder and ammeter shunt down to that lower mount tube as well, which will allow for a very short cable run from the contactor to the fuse holder. This, in turn, will minimize the length of unfused cable, which is definitely a good thing.

So – back to building. The first step was to transfer the mount-firewall bolt hole locations to the new raw sheet piece. Then I got to repeat the exercise of tinkering with placement of everything until I liked the layout, and making the needed mount holes. This time, I started with the battery box attach points, then worked off of that to position the contactors. The rough layout can be seen below:

Next, it was time to start sketching up the actual outside of the mount. Here I basically just worked between the mount holes and tried to remove as much unnecessary material as possible. I got as far as rough-cutting the outline before calling it a night:

There’s going to be a fair amount more work to do here, easing up to the actual lines, smoothing out a bunch of rough cut sides, and so forth, but another good night’s work probably ought to do it. I’m not sure yet if I’m going to do any more lightening hole besides the large one outlined above – I can probably fit a few more in here and there, but I don’t want to remove too much material.

I’ve also got to order even more stuff from Spruce before I can finish this. I used my last few 1/4” nutplates with the previous mount iteration, so I don’t have any to install here for the contractor mounts. Guess maybe I’ll put together an order tonight, though to be honest I don’t need this stuff right now – it could wait a bit. Pretty sure I can at least mock everything up well enough to work up cables and such. Eh, we’ll see…

OK, so first order of business this evening was to get the roughed-out mount drilled to the firewall. The challenge here was figuring out some way to hold the plate in place while drilling the first hole. I didn’t even need it to be held tightly – I figured if I could just make a starting dimple in the plate at about the right location, I could then finish the hole off the airplane and use that first hole as a reference.

Eventually I ended up using one of the most important tools in anyone’s toolbox – that’s right, duct tape. The lower right corner of the mount plate rests on the rudder anchor block, so the tape really only has to keep the mount from rotating counterclockwise around that reference point. Two strips do the job just fine:

The rest of the holes were pretty easy; in all cases I initially drilled #30 to match the existing hole size in the firewall, then I went back and enlarged each hole to #12 for an AN3 bolt.

Next up was adding the mount points for the contactors. The basic idea is to mount these as high as possible, which will then enable the battery box to also be mounted as high as possible, and in turn ensure plenty of clearance between the box and the nearby lower engine mount tube.

I did end up doing some ad-hoc replanning here, though. My initial plan was to add a second .063” sheet here, which would give me enough thickness to insert flush 1/4” screws from the back of the mount; these would be then secured with jam nuts and lock washers, creating the same sort of “fake studs” I used for the avionics stuff on the baggage bulkhead.

I’ve never really liked that idea, though, and as I looked at everything I decided that things could be really simplified here if I just didn’t insist on having the mount actually sit flush on the firewall. If I could add some standoffs and space it off by 1/4” or so, then I could just use regular old nutplates and bolts to attach the contactors. So I decided to go that route, and instead of riveting a doubler here and doing some annoying countersinking, I just had to lay out four nutplates to match the mount holes.

The final product is seen below. Note that there’s a bolt hole here for securing the plate to the firewall, flanked by the pairs of mount holes for the master (left) and started (right) contactors.

Next up is finalizing the battery box location and getting those holes drilled. Which has me thinking now – originally I was going to rivet the box to the mount, but now that the mount will be spaced off the firewall, I can go with bolts and nutplates there as well. That should simplify battery installation and removal – I was figuring on that requiring loosening the bolts for the mount plate itself, allowing the box to tilt and clear the firewall flange, but this way it’ll only require loosening the box bolts, which should be a little less unwieldy.

Anyway, hopefully tomorrow I can get that fit-up done, and then I’ll set about strategically removing significant material from this plate to lighten things up.

So as alluded to last time, the work since then has revolved around nailing down the battery box mount layout. Basically, I did some incremental trimming on the mount plate I rough-cut last time out, and then transferred some of the location lines I’d drawn on the firewall onto it – stuff like rivet locations and a line I drew to approximate where I wanted the battery box to go.

This mount is actually going to sort of do double duty – in addition to mounting the battery box, I’ll be mounting the master and starter contactors on this plate as well. So that makes for some additional layout work to be done, much of which I was firming up earlier this week.

Today i transitioned into figuring out exactly how I wanted to mount the plate to the firewall. The general plan has always been to remove a few of the existing rivets and enlarge their holes for bolts instead. Today I was figuring out which of these existing holes to use – ensuring I picked ones that wouldn’t interfere with the battery or the contactors, roughing out those locations on the plate, double-checking things…let’s just say “multiple” times.

Finally, I was happy with the rough layout, to the point that I felt like it was time for the engine to get out of the way – so I brought over the engine fixture and pulled that beast off, hopefully for the last time. With it out of the way, I can get to work on finalizing a few different firewall items. The most obvious of these are the battery mount and pressure manifold, but there were also a couple rivet hole that I never filled before for some reason, plus I want to fit the eyeball passthroughs for the control cables. So my first order of business after removing the engine was to mark up all this stuff on the firewall, as a sort of visual checklist.

Those missing rivets got taken care of first up, then I moved to removing the rivets where the battery mount holes will go. With those out of the way, it seemed like a good time to call it a night. The next order of business will be to figure out how to hold the mount in place while I use the rivet holes to drill #30 pilots into the mount – that will fix its location, and once that’s done I’ll drill them to final size, then get to finalizing the mount itself.

Yes, it’s me again. I guess the motivation switch has flipped again and I’m back to doing stuff. Basically, I’m continuing with the goal of finishing layout stuff that I want the engine in place for; once that’s done, I’ll remove it again to provide good access for poking holes and such into the firewall, and then when it goes back on it can be permanent.

One thing I’ve been mulling over a bit for a week or so has been the location and layout of the pressure sender manifold. This little dude gets mounted on the firewall, with incoming lines for fuel and oil pressure, and then the actual pressure senders get attached as well. An interesting tidbit here is the orientation of this device. For whatever reason, the OP plans for an injected engine call for placing the manifold vertically, and adding a small stiffener on the backside of the firewall for support. The carbureted OP plans, on the other hand, place it horizontally, and the existing firewall angle provided support.

It seems to me that it’d be much easier to use the horizontal placement and not have to add an extra piece. I asked around on the Van’s forum and there seems to be no reason for the orientation difference, and plenty of people have done the horizontal setup, so that’s why I’m going with. So I installed the oil pressure fitting on the engine block, installed the fittings on the manifold, and put the hoses in place. This allowed me to experiment with placement, and ensure that I liked the way the houses were routed.

With a little bit of trial and error, I worked out the location I wanted, as well as which two of the three manifold ports I’d be using. This will be ready for the mount points to be drilled once the engine comes off:

Next was the age-old problem – working out the battery mount area. I’ve mulled this one to death, over and over again, and it’s past time to stop mulling and start doing. At first I was going to use some cardboard to mock up the mount plate, but given that things are pretty straightforward here, I decided to go straight to cutting on one of my sheet pieces I bought for this. Here again, it took a bit of trial and error to get the angles to match like I wanted, but I’ve at least got this roughly cut the way I want it:

My general idea of how to go from here will be to find a way to fix this in place on the firewall, and then do a full mockup with the battery box, as well as the master and starter contactors. Once I get that done and I’m happy with the layout, I think it’ll be time to pull the engine and start making holes…which is a little scary, but it’s got to be done.

Well, the work ethic still hasn’t been great, but I keep trying to chip away. Over this past weekend I did some more poking around with how to lay out firewall stuff. Deciding on the battery box position and orientation was helpful, but there was still the question of other electrical stuff. Specifically, I also need to locate the master and starter contractors, the ammeter shunt, a big fat ANL fuse to protect the alternator B-leads as well as the supply line to the fuse blocks inside the cockpit, plus the battery bus and e-bus relay.

Basically, there’s a bunch of stuff here and a lot of considerations. I’d like to avoid placing anything so that it’s a huge pain to access for service. At one point I was considering locating the ANL holder and shunt inboard of the battery box, but that would mean that if that big ANL fuse ever popped, I’d have to pull the whole cowl and probably crawl under the airplane to service it.

The contactor locations, at least, were straightforward: I can place both of them just above the battery box. The battery bus and e-bus relay can probably go basically anywhere; they barely weigh anything and thus I don’t need to worry a lot about the structure they’re attached to. But positioning that ANL holder and shunt was giving me fits.

I eventually arrived at a somewhat obvious solution – namely, neither of those need to be mounted to the firewall. And since they’re both sort of oblong pieces, each with two large screw holes, they’re good candidates for just mounting on an engine mount tube with adel clamps. I tried a few different spots, and for the moment they’re living on one of the upper tubes. I think this location should be good, though one of the fun things in the back of my head is where lots of other wires and things are eventually going to be routed.

Still, I feel good enough about this to go ahead and work on the mount plate for the battery box and contactors. I think the biggest obstacle for that is going to be getting over my reluctance to go drill holes in the firewall, but it’s got to be done.

I also did some other tinkering along the way; for example, I wanted to have some general mental picture of where the fuel and oil lines to the pressure sender manifold would live. That required some digging into plans and researching. (example: where does the oil pressure sender line even connect?)

In any case, I think this is the point where there’s nothing for me to do but to pull the engine back off and get going on that battery mount. I’ll also want to drill the holes for the control cable passthroughs while the engine is out of the way. One of these evenings I’ll work up the wherewithal to do it…

Well, not a ton of shop time today thanks to other stuff going on (including unexpected mower maintenance), but I still got some stuff done. I decided it was high time to move the engine back to the fuselage so I could finalize things like the battery box location. Moving the engine took a bit more time than I expected…but still better than the initial hack getting it bolted to the mount.

The next bit of fun was playing with the battery box. I already knew that I wanted to mount it low on the right side of the firewall, but there were a couple questions still to answer, mainly 1) exactly how low to mount it and 2) whether to orient it with the top of the battery up or sideways. There’s also the consideration of being able to tie the backer plate I’ll be making for the box into the firewall angles.

To make a long story short, I’m going to mount the box sideways. With the top up, the upper left engine mount tubes become problematic for getting the battery in and out, unless the battery either goes so far to the center as to make the backing plate a problem, or so low that tying into the lower angle is also a challenge.

The downside to this position is that the firewall flange will be in the way of removing the battery, which means that I’ll have to loosen the mount bolts to the firewall for battery service. This will be mildly annoying, but not horribly so; with the box so close to the edge, access should be very good here.

The other thing I wanted to verify was the fuel hose routing from the firewall to the mechanical pump. This was to verify that the fittings I had would allow for suitable routing – I was pretty sure I could make it work, but definitely wanted to verify. And I’m happy to say that it looks just fine:

I suppose next steps will be to draw the final location of the battery box, the start looking at where I want to put the master/starter contractors, the battery bus fuse block, and the E-bus relay. Once I get the layout finalized…I get to remove the engine yet again and start working out actual mount hardware and such.

Today I decided to start by working on the other half of the flywheel-area stuff for the SDS ignition. Previously I installed the hall sensor, now I just needed the actual magnets in the flywheel to trigger that sensor. The procedure itself is fairly straightforward, and Ross provides both clear instructions and a nice drill block for the job, but there’s still a bit of nervousness that comes with poking holes in a shiny and no doubt expensive engine part.

In short, the procedure calls for installing two trigger magnets 180° apart, plus a sync magnet near the first trigger magnet. Existing holes in the flywheel are used, along with the timing marks, to position the drill block in the three required positions. At each spot, the block is secured with a pair of bolts, and then it’s drilling time. We’re going through a good 3/4” or so of material, so it takes a bit of time for each hole, and you end up with plenty of chips:

Next, after drilling all the holes, each one gets tapped for an allen-head set screw, which will be used to put the magnet in the proper radial position. Note the markings inside the flywheel; this is the #1 trigger hole I’m tapping, with the sync hole just to the left:

Next, we install the set screws, and test fit a magnet in each hole, adjusting the screw until the magnet sits flush with the inside flywheel surface. Finally, we remove the magnets, mix up some epoxy, then dab it in each hole before reinstalling the magnets:

There is one last step, which doesn’t merit a photo: after letting the epoxy cure, a second set screw is installed in each hole, with a bit of Loctite, thus providing some extra security that nothing will come loose.

After having some dinner, I decided to start looking at the engine baffling. I actually unpacked all this stuff a couple nights ago with the intent of doing this, but got slightly intimidated at the sheer number of parts and had one of those moments where I had to set it aside and come back with a clearer head. As per usual, the second look at the parts and plans made things seem a lot clearer. It was still obvious that I wasn’t going to start really assembling any of this stuff yet, but I did want to get a big-picture idea of how it would all fit around the engine, to identify any issues I might have with all the other systems stuff I’m doing. Sure enough, a few things presented themselves immediately.

The first item is at the rear of the case. Here, the vertical back portion of the baffling is braced against the case with a little gusset piece, which uses the two rear upper case bolts to attach to the engine. This it notable because these are the same two bolts I was going to use for the coil pack mount. This probably isn’t a super difficult job to solve, but I definitely won’t be using this piece – I’ll need to fab up something that will end up being part of the coil pack mount.

The next item is one that I knew was coming, but is still worth noting. Most Lycoming cylinders have fins at the base with a, well, cylindrical profile. Titan/ECI cylinders, on the other hand, have a tapered/conical profile. The result is that the provided baffle pieces in this area won’t fit the Titan cylinders very well.

Here’s one example; we’re looking at the #2 (left front) cylinder. The piece I’m holding will form a ramp between the cylinder and the air inlet on that side of the cowl. Keep in mind that the purpose of all this baffling is to force the flow of cooling air as close to the cylinders as possible:

The issue is more obvious in a close-up photo: the gap between the baffle and the tapered cylinder is evident here. This is an area where air isn’t going to be kept close to the cylinder. Also somewhat visible is a curved piece of material that wraps around the cylinder; this also isn’t going to fit close to the fins.

A similar issue will exist at three other places: on the other inlet ramp to #1 cylinder, plus similar pieces that butt up to the #3 and #4 cylinders at the back of the engine. Fortunately, this is a solved problem; previous builders have fabricated new pieces to better fit the conical profile, and even have templates available online to cut these pieces. The existing wraparound bits will be cut off and the new pieces riveted in their place.

Finally, we come to the front of the engine. Here we have another vertical piece, which fits tightly around the case just behind the crank snout. Another wide shot gives an idea of the big picture:

Moving closer, we can see the issue here – that nice big cable guard I made for the hall sensor protrudes too far back. I can’t even slide this piece down to where it’s supposed to be with that guard in place. So I’ll have to remove that when the time comes to fit the baffling, and get it trimmed to fit better:

All this baffling stuff also raises some order-of-operation concerns. I’ve been holding off on riveting the forward upper skin in place until I can finalize the wiring runs. Finalizing those runs requires getting the engine hung and at least some of the wiring fed through, most notably the ignition stuff. Finalizing those runs in the engine compartment, in turn, will probably require doing some baffle fitting to handle spots where the runs will need to penetrate the baffling. It’s possible that properly fitting the baffling will require having the cowl in place. And I don’t think I can fit the cowl until…the forward top skin is riveted. Maybe. I’m not at all sure there’s actually a problem here, but it’s going to be a thing to keep in the back of my head while mucking with FWF stuff.

Ok, enough of that…let’s get on to a few more minor items. Last time I was concerned about the mechanical fuel pump’s inlet fitting, which I couldn’t remove without removing the pump itself. The main concern I had about plumbing with the provided 45° fitting in place was that the fitting is pointing to the right side of the aircraft, whereas the firewall penetration for fuel supply is located to the left of the pump. That is, a slight difference in fitting orientation could require a somewhat longer fuel line.

However, a potential solution occurred to me: I had an extra 90° AN adapter, which was originally installed on the injection servo. Since the custom hose I got has 90° fittings on each end, that adapter was now unused…and adding it to the inlet fitting means I now have a potentially straighter shot to the firewall penetration. This would also give a lot more freedom for orienting this fitting to work nicely with the line. It’s still something to test fit next time I hang the engine, but I feel really confident I can make this work without having to remove and then reinstall the pump:

The last item was fixing a long-incomplete task. Back when I first got the engine installed on the mount, I was only able to fully tighten three of the four mount bolts. For the fourth, the nut on the forward side of the mount was super close to the #4 pushrod tube. I could get a wrench on it to start tightening the bolt, but as more and more of the bolt protruded, it would end up trapping my box end wrench. And there’s no room to use the open end in the engine case recess.

This was actually why I originally bought that cheap wrench set – the same one I grabbed the 7/16” wrench for to make my torch-bent tool earlier this week. Tonight I finally got around to grinding the 5/8” box end down to a really slim head, which can fit in the tight space and allow the bolt to be properly torqued:

Whew! That was a lot of writing for a relatively small amount of shop time. I think it may be about time to hang this engine again and start working on some of the fitting/locating work that requires it in place. Maybe that’s what I’ll get to tomorrow.