Exhaust stack too short?

How to keep the Cessna 170 flying and airworthy.

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oldtrucksrule
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Exhaust stack too short?

Post by oldtrucksrule »

So, I have a '48 with a C-145-2 with the "new" exhaust ie, not the pancake. Anyway, the aircraft left, pilot side, seems to hang a couple inches shorter than the other side. It's barely, I mean barely, clears the cowling. I purchased it from AWI so, I assume they sent the correct part. What are your thoughts?

Thanks, Cory
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GAHorn
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Re: Exhaust stack too short?

Post by GAHorn »

I have two thoughts:

1- Did you contact AWI about this? (Did you order and receive the correct part number?)
2. Do you have a pic?
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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oldtrucksrule
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Re: Exhaust stack too short?

Post by oldtrucksrule »

I have not reached out to AWI, I'll be perfectly honest, I haven't received the customer service from them that most talk about. It involved a motor mount they botched up pretty bad. So, I thought I might get a better response here.

I'm having difficulty inserting the picture but, here is a link.

https://onedrive.live.com/?cid=F15C6DE4 ... 355&o=OneU
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c170b53
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Re: Exhaust stack too short?

Post by c170b53 »

I’ve had a mount returned with the same large bend it had before the repair. When pointed out it came back 2nd time perfect. Unbelievable but mistakes do happen, even to best right George ? :twisted:
I’d contact them again and ensure they know the status of your exhaust. A measurement on your part, probably would not hurt.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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GAHorn
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Re: Exhaust stack too short?

Post by GAHorn »

The link does not work…

I’d suggest you call AWI and talk to Charlie Felds directly.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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oldtrucksrule
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Re: Exhaust stack too short?

Post by oldtrucksrule »

I’ll give them a call tomorrow. Thanks
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GAHorn
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Re: Exhaust stack too short?

Post by GAHorn »

oldtrucksrule wrote:So, I have a '48 with a C-145-2 with the "new" exhaust ie, not the pancake. Anyway, the aircraft left, pilot side, seems to hang a couple inches shorter than the other side. It's barely, I mean barely, clears the cowling. I purchased it from AWI so, I assume they sent the correct part. What are your thoughts?

Thanks, Cory
I only quoted the “originating” post to introduce addt’l comments:

There are significant differences between the “Original” or “Straight” Cessna 170 (also unfairly/diminutively known as the “Ragwing”) …and the 170-A…. and Versus the 170-B (which is further split into at least two groups based upon cabin-ventilation differences that occurred about the “1953” year-model ….(and which is further complicated by the FAA system of year-model registrations VS actual Design Year Model differences.) This latter situation is a significant example of why aircraft SERIAL numbers are important when discussing actual differences and when identifying Part Numbers.

The 170 and the 170-A, when first mfr’d, used the so-called “Pancake” style of mufflers/exhausts. This system is NOT interchangeable with the later “Hanlon-Wilson” mufflers/exhausts…. and further, based upon 170-B airframe serial number….the Right-Hand side exhaust changed further when the cabin-ventilation/heating system was modified/improved about 1953.

Further complicating this issue is the introduction in late 1955/56 of the C-172 which outwardly appears to mimic the late 170-B… but makes a subtle change of exhaust design almost immediately with the 172-B and continuing for several years until the mid-to-late 1960s. (An example of this is the “studded mufflers” of the 170s versus the “smooth” mufflers of the 172 series….with the accompanying “bent” versus the “straight” tailpipes. (This creates a complication when hodge-pod “data-plate re-builds” are found that may mix parts of fuselages of 170s with firewall-forward of 172s. Until repair parts are needed some owners can remain unaware of the modifications their airplane may have undergone in a prior life.)

This becomes a real problem for owners of Cessna 170, 170-A, and 170-B aircraft that have undergone alterations that may pass completely unnoticed and in many cases UN-recorded…. which used cowlings, engines, and ventilation/heating components “borrowed” from airframes of different/later Serial Numbers.

The most obvious change occurred with the switch from Pancake to H-W mufflers. (And BEWARE…. It is not unheard of to see an early 170/170-A with one Pancake and one H-W muffer…. different designs on each-side which is NOT approved.)

When the early Pancake system is found to be un-repairable the simplest solution is to convert the entire exhaust system to the HW system…..and when that conversion occurs the 170/170-A engine installations require that TWO LEFT-HAND mufflers be installed from the early HW system.

When THIS DISCUSSION-THREAD popped-up the first thing I thought of was that a botched conversion may have occurred in the airframes’ past that utilized a mis-match of tailpipes….or utilized a “customized” tailpipe system that does not conform to approved systems. Of course, it’s also possible that verbally-ordeing replacement parts that did not directly refer to applicable part numbers of approved conversions may have resulted in the incorrect parts being shipped/installed.

Then, of course, unlikely tho’ it might be, it’s possible a packaging/shipping error has occurred….or even more unlikely a mfr’g error.

Using the following illustration….when converting from a Pancake system to HW… Two LEFT HAND mufflers are used on all 170/170-A models prior to Serial Number 25373….later serials will utilize the differently designed RH Muffler. (Notice the different RH muffler has large “Rings” moulded into it’s ends to accommodate the post-1953 cabin heating system.) Notice also the “bent” tailpipes.
Hanlon-Wilson System for all 170s thru early 172-A aircraft.
Hanlon-Wilson System for all 170s thru early 172-A aircraft.
In the 70-plus years since the 170 was introduced many of the airplanes (if not ALL of them) have “borrowed” parts/designs from later models and from the very different 172 model aircraft. To the untrained eye they may sit on the ramp and appear to be the same aircraft…but they are actually very different. The following illustration is the 172 system which is sometimes found to have been “borrowed” into 170s and which is not “correct”.

Notice the “smooth” mufflers and straight tailpipes.
E5CF850F-6238-45F0-8276-3F4FDDB9DA56.png
What may encourage such improper mixing of system is the commonality of the engines used on all those airframes.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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Bruce Fenstermacher
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Re: Exhaust stack too short?

Post by Bruce Fenstermacher »

In '52 the Hanlon Wilson system was introduced on the 170B. It had a symmetrical exhaust system using the exact same parts left and right with the exception of the tail pipes which where identical in every way BUT the angle of the cut at the bottom.

Starting with the '53 model, the cabin heat scat was changed to 3" as well as the run to the cabin. The scat came off the front baffle and into a funnel on the front of the right muffer connected to the heat shroud. Because of the method of attached scat intake, the muffler had to be modified removing the flange from the front. Otherwise the mufflers dimensions are the same as the left and both those used in the '52.

Lower cowlings from '48 through '52 did not change with the exception of the design and depth of the lower cowl lip. The holes for the exhaust are all in the same spot. This is why a '52 Hanlon Wilson system will fit perfectly on all models back to the first '48. This of course if the PMA's parts are actually duplicates of the OEM.

OEM stacks DO NOT stick that far out of the cowl. Been a while since my calibrated eyeball measured a true stock exhaust pipe but my steel trap memory seems to return 1/2" to no more than a 1" being the depth the pipes stick out of the cowl. Too many folks these days, after years of looking at incorrect longer exhaust pipes with their calibrated eyeballs, have a different measurement stored in their steel trap brain. This the correct length pipe appears short to them.

Show us a picture of your short exhaust. It may not be short at all. Your "correct" length pipe may be to long.
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oldtrucksrule
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Re: Exhaust stack too short?

Post by oldtrucksrule »

Thanks everyone for the help. The knowledge of this group is STAGGERING! I'm going to go to the hangar this morning and get some measurements and better pictures for the "investigation".
20220109_174152993_iOS.JPEG
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GAHorn
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Re: Exhaust stack too short?

Post by GAHorn »

oldtrucksrule wrote:Thanks everyone for the help. The knowledge of this group is STAGGERING! I'm going to go to the hangar this morning and get some measurements and better pictures for the "investigation".
The attachment 20220109_174152993_iOS.JPEG is no longer available
You may also wish to rotate the tailpipes so that the angled “cut” faces forward as originally designed instead of aft. This should keep more stains off the lower cowl. (the active imaginations of some folks cause them to think the relative wind somehow “fights” the engine exhaust and causes backpressure to inhibit performance…. which borders on silly…. The side-view of the area should appear that the cut of the tailpipe parallels the lower cowl slope.) If they are reversed then they are also swapped side-to-side and may affect this appearance you are addressing. (Is the right side tailpipe also AWI produced?…and are the right and left mufflers the same mfr’r?…I.E. were both systems replaced at the same time using the same supplier?)

B28723AE-6D4F-4028-A195-15468F8A5B6C.png
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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oldtrucksrule
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Re: Exhaust stack too short?

Post by oldtrucksrule »

This makes a ton of sense; I will flip flop and see how it looks.

The tailpipes were from AWI and the exhaust collectors were rebuilt by AWI. If the above doesn't work I'll give Charlie a call at AWI.
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Bruce Fenstermacher
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Re: Exhaust stack too short?

Post by Bruce Fenstermacher »

Those aren't short at all. The right pipe is too long. That is if you wanted the stock look. I'd swap them so the angle is forward and cut the long one (now the left one) to match the right.

Of course as I noted, the length of these pipes has creeped longer and longer over the years in an attempt to keep the cowl cleaner. Many folks would like your long pipe length and want the short tone to match.
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hilltop170
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Re: Exhaust stack too short?

Post by hilltop170 »

Longer tailpipes don’t equal cleaner cowl. I use Aero Cosmetics' Belly Wash, now called Belly Cleaner on the exhaust stains. It literally melts the stains off and will not damage the paint.

https://www.youtube.com/watch?v=kPtxzTzMjes
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10 hours of run time.
Last edited by hilltop170 on Mon Aug 08, 2022 5:58 am, edited 2 times in total.
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1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
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darhymes
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Re: Exhaust stack too short?

Post by darhymes »

I wonder if those pipes will be equal lengths once they are swapped around and oriented properly. I’m curious to know what the end result is.

X-IT Carbon Remover does a fantastic job of removing the exhaust stains as long as your paint isn’t oxidized.
Dustin Rhymes
'55 170B N4410B S/N 26754
'06 G550 “The Silver Bullet”
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GAHorn
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Re: Exhaust stack too short?

Post by GAHorn »

darhymes wrote: ….
X-IT Carbon Remover does a fantastic job of removing the exhaust stains as long as your paint isn’t oxidized.
Dow-Corning “Scubbing Bubbles” bathroom cleaner will as well. It’s always a good idea to wax that area before it gets nasty also.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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