My Cessna 170 rebuild thread. XPMODS

malichite

Pre-Flight
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Jul 12, 2021
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Display name:
malichite
Hi. I'm new here. Cessna 170 owner in the PNW. Wanted to start a thread here to share my current project. I purchased this 170 from a friend. It's a 1953 Cessna 170b with tons of upgrades already. Horton STOL, gap seals, pull handles, 1 piece windshield, baggage door, pponk gear boxes blah blah blah. We call her Beige Betty. Not long after getting her, the project took off. 60901834176__70A67C3A-E207-4D8D-AF42-5435D2777DEB.JPG Anyways, I hope you enjoy.
 
About 5 months after getting her, the engine gave up the ghost. Wrist pin was walking out and making metal, one trashed piston, cam shaft was wearing on the first lobe, stuck valve, on and on and on...So this started the big build. Off came the engine and mount getting ready for an upgrade.

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Moving up on the fuel system. From the header tank, we need to add a return line to get the fuel back up to the tanks. We repurpose the wing root vent lines to be return lines. After a bunch of work, we have all that in. Here you can also see the header tank located down in there. After all this is complete, we will need to get the tanks pulled, and get new vent lines added outboard. The new vent setup will work like newer 172s with the vent line coming from the bottom of the wing located behind the wing strut.

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Moving outboard we get the wing vents installed. Here is the first one in the wing. Once complete, make a template to match the holes for the other side. Dont forget the other wing needs to be a mirror image. Little note so I dont screw it up.

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With the new engine, we are required to have fuel pressure and manifold pressure gauges added. Where to put them?

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I have an idea! Lets order a JPI900 and make a new panel!

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That looks like more space. Now, how to cut holes into the panel. Here I 3d printed a few jigs so I could use my router and a flush cut bit. Think it worked out pretty well.

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Quick little clip of how the router works for cutting out the holes.


Now we wait for JPI to get through their backorder queue.
 
While we wait for that to show up, we are most likely going to have a CG problem. We are also not going to be able to fit enough into the airplane to take advantage of the new power, so seems like we can kill get two birds stoned at the same time or something something something. Behind the baggage bulkhead we have our strobe and ELT. About 4 1/2ish lbs. If we take that whole assembly, rotate it 180* and move it back one bay, thats a decent arm for that weight. It will also get that mess out of our way to add the extended baggage. Lets get at it! First thing first, make new support bracket to match the current one. It's tiny back there, better send in the girlfriend.

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Once that's all worked out, lets drill some holes in the airplane again.

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Add some nut plates

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and get back in there to do some riveting.

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Now we can get all that stuff mounted again.

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Also, taught her how to lace wire. I should go in and inspect her work. Or maybe take a nap.

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Last, after a few more holes and nutplates, install it. Next we need to figure out what to do about that headliner

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The rear battery STC puts it where the floor of the extended baggage is unfortunately. I think we will be ok on balance. If not, it seems like a great reason to get a baby bush wheel and maybe add built in oxygen behind the extended baggage.
 
Now with the back of the airplane worked out, lets turn our attention back to the front. Before we get too deep, we need to see how the cowling fits. With this STC, some airplanes will have interference with the induction system. The STC allows the induction system to be flipped if this is the case. Lets roll the dice and see.

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Well crap. No big deal, unbolt it all and turn it around right?

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Well crap, that doesn't fix. Time do do some more modifying. The oil fill tube interferes with the induction tube now.
 

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Lets put a bend in that. After a little work and some welding, the oil fill neck fits around the induction tube.

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Lets see how that cowling fits now with the induction rotated 180* Looks like it fits much better. We had to cut the ends of the induction tubes off as well to get them to fit, but fits great now. (This is all called out in the STC)

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Now that induction is worked out, onto the exhaust. The exhaust for this STC calls to cut off the flanges of the original O-300 exhaust and weld on IO-360 flanges. Seems simple, straight and straight forward. A selling point maybe even? Yah no, this is an absolute mess. We managed to get it all in there but everything is insanely tight. I'm not super thrilled about it but for the short term it will work until I come up with something better. All and all I'm not that upset though. It exits exactly where it did originally so will help keep the sleeper look.

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Sorry been a ton of posts to get caught up to current state. This is where we are at now finally. The rest of that was the preceding 6 months.

JPI arrived finally, time to get onto fuel lines and wiring. Lots more lacing and logistics to work out.

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I think that mostly catches up where I am at now. I'm hoping to complete getting the wiring back up under the panel this week and try to get the panel firewall back closed up and complete for good. All that will be left then is firewall forward.
 
This is becoming my favourite thread. Love the way you write, the pics are awesome and it just looks like ya'll are having fun putting all this together. Respect for the pic with the cold CL, too. :)
 
This is becoming my favourite thread. Love the way you write, the pics are awesome and it just looks like ya'll are having fun putting all this together. Respect for the pic with the cold CL, too. :)
CL? You mean the old civic hatch?
 
CL? You mean the old civic hatch?

Ha no.. Le Silver Bullet.... good after a hot day flying or after performing airframe/engine work....
 
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d'oh that's what I meant... after performing the work... lol not during. Or while supervising.... :)

So many wires with that JPI.... we are thinking about the 830 when our engine requires the inevitable OH.
 
It is a lot, but not that terrible. They send the harness all terminated at the instrument side and everything is labeled very well. I just made sure to group everything into bundles (Right side cht/egt, left side cht/egt, 3 pressure transducers...) and then ran them where they needed to be.
 
Got the wiring complete on the right side of the engine. Also finished getting the last fuel lines made. Just need to get them bundled up. Also getting the last of the panel side wiring complete. Starting to smell like a first start soon.

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CHTs and EGTs wired up on the left side, fuel flow, oil pressure wired up. Still need to secure the wiring on those. Also need to figure out routing for the upper plug wires still. 99% of the wiring now complete inside as well. The punch list is getting pretty short.

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That battery box looks like a tight fit to install battery ? Or is it just the angle picture taken from ?

Like the build , it's interesting to follow.
 
I think it's the picture. It is tight, but I can get it in and out in a couple min.
 
What is the installed weight of the engine vs the old O-300?
 
The constant speed prop is where most of the weight gain happens, and it happens all the way forward. But it’s not too difficult to manage. The Hawk XP is a great performer on a platform originally made for the 0-300.
 
Not sure on final weight yet. Doing W&B this week. Im hoping the 4+ish lbs we moved almost to the tail will help contract and weight of the prop.
 
First start done! IA came down yesterday and inspected everything. Couple minor things to wrap up and we are ready to fly. Paperwork getting filled out now and hopefully we will be in the air by the end of the week.

 
Excellent set of photos. Just be sure to label and file in some order so they'll be use to you later.
 
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