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PA-12 cabin heater box and other firewall forward jobs :)

Philly5G

Registered User
England
I'm about to start on the removal of the old O235-C and fitting of the new O235-C2C engine in my 12 and will be doing a number of fixes and upgrades whilst the original engine is out. I would appreciate feedback on any and all of the following please :)


  1. The exhaust muffler looks like it's either for another aircraft or it's been fitted upside down, as the port that looks like it should go to the heater box is pointing down and straight onto some metalwork below, can anybody please post a pic of their 12 muffler, preferably connected to a heater box, so I can see what the arrangement SHOULD look like? I'd also really appreciate a pic of a 12 heater box, as there was something that looks like a heater box which I found in the storage bag behind the rear seat when I bought the aircraft, but I'm not 100% sure :roll:
  2. Although all the baffles appear to be there, a lot of them have very big holes and gaps in them, particularly the rear top one. Should the baffles sit tight against the engine and cowls? and could anyone please put up a photo of a complete and "how they should look" PA-12 baffles set for an O235 so I have something to aim at. Some in situ pics would be REALLY helpful too 8) As you'll see in the pics below, some of the baffles have a kind of foam attached to their edges, is this standard? (By the way the tape around the Rocker covers is heat resistant tape that I used when troubleshooting the source of the oil leaks!!)
  3. I exchanged the mags for new Slick 4370/4371 and also a lovely red Kelly harness :up When I looked under the cowls again yesterday, I noticed that the (at least the lower plugs) have a 90 degree fitting on the original harness, but the Kelly has a straight fitting. I can swop the Kelly out if necessary, but wondered what other people are using? I'm assuming that with the appropriate clip placements the straight fittings can be positioned to loop around and stay away from the exhausts?
  4. As the engine I'm fitting is zero timed and essentially new, in addition to the straight oil we'll be using for the break in period, I'm thinking of starting on the right foot and using CamGuard or similar, what's the collected opinion on the value of this kind of treatment?
  5. Again, because the engine is new and lovingly just inspected and painted I'm considering fitting a spin on oil filter, I know this has been covered in other threads but I'm thinking Casper, I'd appreciate opinions on this and whether the Casper will actually allow the tacho cable in the pic to route straight past?

Thank you in advance and I'm sure there'll be more questions before much longer :roll:

Philly

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Just an FYI, I got a field approval to put a Sutton exhaust on my PA-16 with an O-235. 6 lbs lighter, and gets rid of the muffler AD. The O-235 is 3/8 narrower at the exhaust ports than an O-320, so it takes a little playing around to get it to fit without ant stress on the pipes and muffler. Haven’t run it yet, looking forward to that, but likely will be a while as I’m just at the beginning of the restoration.


Sent from my iPad using Tapatalk
 
CamGard, perhaps a little like Holy Water you're not sure it really works but you would never walk by without splashing a little on.
But if you do, not before engine is well broken in.
 
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CamGard, perhaps a little like Holy Water your not sure it really works but would never walk by without splashing a little on.
But if you do, not before engine is well broken in.

Great tip, thank you 40m, I hadn’t realised yet that Cam Guard is post run in cycle [emoji106]


Sent from my iPhone using SuperCub.Org mobile app
 
Baffles should be tight to cowling all the way around (I prefer felt). All small gaps on metal baffle closed with RTV or similar stuff.
DENNY
 
The Caspar oil filter works fine with the standard /straight tach cable. At least on the 320 it does, that's what I have.
 
some firewall pictures in this album of mine, https://goo.gl/photos/PuiR5ha2aBDbkUBS8

but it had a short mount/different heat system(Pa-18?)...(Mckenzie? STC)

WOW!!! Thanks for all this Mike!!! there's some BRILLIANT detail stuff here!!!! (nice shirts by the way) I can see what looks like a heater box at the bottom of the firewall with its control cable coming from behind and down the starboard side of the firewall, but I don't see where the heat comes into the cabin? There seems to be a blanking plate on the cabin side of the firewall where the heater box would be, does it have a firewall forward scat tube or similar to duct the heat in somewhere?

A general question, does the engine mount bolt through the firewall into the holes at the 4 corners at the front of the fuselage frame?

Thanks again and looks like a LOT of work being shown in the pics 8)
 
Phil, That felt is the original baffle seal material. All it really does is to keep the metal baffle materiel from chewing on the cowl. It doesn't really maintain the sealling characteristics under all conditions. I like the wide Silicone baffle seal material. When care is taken to ensure there are no puckers in the installation, it lays down smoothly and does an excellent job of improving the cooling. https://www.aircraftspruce.com/search/search.php?s=baffle

I have seen improved cooling when changing to the silicone.
 
Phil, That felt is the original baffle seal material. All it really does is to keep the metal baffle materiel from chewing on the cowl. It doesn't really maintain the sealling characteristics under all conditions. I like the wide Silicone baffle seal material. When care is taken to ensure there are no puckers in the installation, it lays down smoothly and does an excellent job of improving the cooling. https://www.aircraftspruce.com/search/search.php?s=baffle

I have seen improved cooling when changing to the silicone.

From looking at the Spruce photos it looks like the silicon attaches to the metal part of the baffles and fills up the gaps without need of the foam stuff, so it’s basically just the metal frame and the silicon, is that correct?


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From looking at the Spruce photos it looks like the silicon attaches to the metal part of the baffles and fills up the gaps without need of the foam stuff, so it’s basically just the metal frame and the silicon, is that correct?
Yes. Just lay the silicone flat before drilling holes. Do not twist it so that it puckers between the fasteners. This is easy to see when you are working with it.
 
…..As the engine I'm fitting is zero timed and essentially new, in addition to the straight oil we'll be using for the break in period, I'm thinking of starting on the right foot and using CamGuard or similar, what's the collected opinion on the value of this kind of treatment? ….

As already pointed out, no camguard til after the engine is broken is.
I would also say no Lycoming additive or Aeroshell + oil that has the Lyc additive in it.
Which "straight oil" are you gonna use for break-in?
Used to be that ECI recommended using regular Phillips 20/50.
I would check with whoever mfr'd your cylinders & see what they recommend.
 
Phil, That felt is the original baffle seal material. All it really does is to keep the metal baffle materiel from chewing on the cowl. It doesn't really maintain the sealling characteristics under all conditions. I like the wide Silicone baffle seal material. When care is taken to ensure there are no puckers in the installation, it lays down smoothly and does an excellent job of improving the cooling. https://www.aircraftspruce.com/search/search.php?s=baffle

I have seen improved cooling when changing to the silicone.

McFarland has some no-chafe stuff that’s a little stiffer. I’ve had it on for 3 or 4 years now and it’s still tight to the cowl.


https://www.mcfarlaneaviation.com/products/product/CS085X3GBF/
 
McFarland has some no-chafe stuff that’s a little stiffer. I’ve had it on for 3 or 4 years now and it’s still tight to the cowl.


https://www.mcfarlaneaviation.com/products/product/CS085X3GBF/

Thanks for this and looks really well thought out. Interesting that the spec specifically refers to silicone being not great at all "Typical silicone rubber baffle seals have a coefficient of friction among the highest of any known material. This friction transfers engine vibration into your cowl and firewall causing fastener fretting, fatigue, cracking, chaffing and airframe vibration" does the McFarlane stuff really make such a difference?
 
Pictures of 150 hp PA12 in my shop right now. Modified with Sutton exhaust. Has Airforms baffles.
https://photos.app.goo.gl/t8e6eoQniX3jfM7x9

WOW!!!! THANK YOU for these Steve!!! These are pretty much exactly the clean, fresh and well-ordered look I'll aiming at!!! I'm loving the pic of the straight fitting HT leads being routed via the Rocker cover bolt clips, that's answered Question #3 PERFECTLY!!!

I can see the heater box is mounted pretty much the same place on the firewall as mine/the standard one(?) but what is on the other side of the firewall? Just a single hole that the hot air blasts through? or some kind of tubing setup to distribute the heat?

The baffles look fantastic, what kind of material is the non metal stuff?

Thanks again :up
 
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Phil, The materiel which I used was Spruce part number 09-31800. It doesn't seem to be in their catalog any more.
 
Pictures of 150 hp PA12 in my shop right now. Modified with Sutton exhaust. Has Airforms baffles.
https://photos.app.goo.gl/t8e6eoQniX3jfM7x9

Hi Steve this stuff has really helped, thank you!! I went to the hangar yesterday and dug out the heater box I have which is EXACTLY the same as the one in your pics AND it has the valve etc!!

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The position of the firewall hole and the muffler put the heater box pretty close to the muffler, so I'm planning to make an angled adapter and connect it directly to the firewall (as is the one in your pic) tilted back, to get more access to the lower (heat) connector.

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Do you have a pic that shows where the 2 Scat hoses connected to the heater in your pics are connecting to please? I'm guessing the fresh air one is going to one of the intakes in the lower cowl bottom and the heat one to the muffler?

Thanks again :smile: :up
 

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Yes, one goes to a fresh air pickup on the bottom cowl and the other to the cabin heat shroud on the aftermarket Sutton exhaust.
 
Yes, one goes to a fresh air pickup on the bottom cowl and the other to the cabin heat shroud on the aftermarket Sutton exhaust.

Thanks Steve and I've just noticed the hole in the heat pipe fitting? I've also seen the same hole in another heater box pic on supercub.org.

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Why is it there? Seems pretty dangerous as if there's any exhaust leak under the cowling and the heater flap is open, the exhaust gases will be sucked straight into the cabin?
 

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Thanks Steve and I've just noticed the hole in the heat pipe fitting? I've also seen the same hole in another heater box pic on supercub.org.

Why is it there? Seems pretty dangerous as if there's any exhaust leak under the cowling and the heater flap is open, the exhaust gases will be sucked straight into the cabin?

Is that for the hot air from the muffler shroud to dump out if the valve for the cabin heat isn't opened? It would get pretty warm in there if the hot air from the muffler shroud didn't have some place to go. I agree about being concerned about exhaust gas leaks, but remember this is the low pressure side of your engine cowling, so exhaust leaks and hot air from the muffler shroud SHOULD flow out with the engine cooling air. Not all works as it always should, and that's why having a working CO detector is important.

I would be more concerned about exhaust leaks directly from the muffler into the shroud around the muffler.

Jim
 
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There is something wrong in this picture.
The hot air from the heat muff should be coming in that larger tube to the valve box. The outside ambient ram air always passes through the heat shroud, then either overboard or into the cabin. Always flowing. When the heat valve is off, the air should flow through and out the open hole. When the heat is partly on, some hot goes into the cabin and some goes out that hole. When the heat is full on, all of the hot air goes into the cabin.
What is the purpose of that smaller extra hose going down below the hole?
 
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