The International Cessna 170 Association

Has anyone used a 172 exhaust system on a 1948 170? Need some info please

Yes I'm certain I've seen one. And the reason I'm sure that I have is because the 172 mufflers, those Hanlon Wilson mufflers intended for a 172, don't fit. Fact is the 172 Hanlon Wilsons don't fit any model of 170 cowling without bumps in the chin cheeks. The 172 mufflers are larger in diameter than the 170 mufflers.

So I think what you want to know is how do you install Hanlon Wilson mufflers that where first seen on a '53 170B, on your '48. The answer is you follow Cessna's service instruction and buy the all the parts for the left side of a '53 system. But you also buy all the same left hand parts to be installed on the right side of your engine.
SK70A51-1 Hanlon Wilson Muffler Installation 170 & 170A

When I was rebuilding my aircraft initially the exhaust system that was in the box of junk of aircraft parts was a pancake system . It was so broken/ cracked and burnt out ,I felt ashamed throwing it in the scrap metal bin it should have gone into the trash can . It even had patch’s wired on over the holes. I had only a catalogue and that can’t be used as a reference tool for assembly. I couldn’t procure any type of exhausts in my country new or second hand exhausts for a 170 of any model.
We had a new set of 172 exhausts on the shelf for a continental engine . To cut a long story short drawings were made up and sent in for approval. Approval was given in 2 days
[shock /horror] what’s happening ? This normally takes months to come through. Then a small memo was attached saying approval wasn’t required as the same engine was being used etc etc. there was a stipulation that a certain type of resin be used in the blisters on the cowl . It was a very minor mod . I ran those exhausts [172] until I bolted on the 4 banger ,180hp.

ghostflyer wrote:..... Approval was given in 2 days
[shock /horror] what’s happening ? This normally takes months to come through....

‘Roos make longer leaps than the rabbits we have in the U.S.

I take it (since the “news” has stopped reporting on it” ...that you Ozzies have stopped trying to burn the place down?

thanks for the exhaust reply. I am just looking to make it legal cause it is already installed. the lower cowl cheeks look original. BTW someone is using my name looks like. this is the first question I have ever asked. one more question though. landing gear wedges (shim), are they required ? this machine has them on one side but not the other which is making her sit a bit funny. thanks mike

Mike,

Are you sure they are 172 mufflers? I'd measure the diameter and I'm sure someone could report what diameter it should be from their 170 system to compare. I'm assuming the system is other wise the same, a few pictures would help us here. If the same diameter and otherwise the same then I'd think you have a 170 system and it is legal to install per the Service Kit. If you confirm your mufflers are larger in diameter and are 172 mufflers then you would need to have a discussion with your IA.

But I'd think you might be able to convince your IA that the system was installed per the Service Kit substituting the 172 mufflers as a minor alteration to the kit.

As for someone using your name to post. The count under your name is not how many questions you've asked but how many posts you have made. By my count which I can do as an admin, you have started 5 threads and a thread is usually started with a question but not necessarily. You have responded another 10 times to threads you did not start. No one can use your name unless they have access to your password.

mike.bernath wrote:thanks for the exhaust reply. I am just looking to make it legal cause it is already installed. the lower cowl cheeks look original. BTW someone is using my name looks like. this is the first question I have ever asked. one more question though. landing gear wedges (shim), are they required ? this machine has them on one side but not the other which is making her sit a bit funny. thanks mike

Mike, if your mufflers do not “hit” the lower cowling then they are likely the correct ones to install per the Service Kit which replaces pancakes with Hanlon Wilson. Here is a link to the Service Instructions which you can use to inspect what you have installed and have your inspector/A&P log it for you.

http://cessna170.org/forums/viewtopic.php?f=36&t=6919

i'm with George. I've seen several 172 exhaust installs. Most have bumps in the cowl. I've know I've seen at least one that hit the cowl. They don't fit and if yours do you likely have the correct mufflers.

thanks, I am the IA, A+P 40+ years now but mostly helicopter. Yes my lower cowl has very well done (bump outs) previously installed. Yes I think this Cessna kit will be my legal out. Not worried about the safety just the legal end of things. again thanks. mike