The International Cessna^® 170 Association

Just noticed another interesting thing about the '56 photos we have in our library. Looks like all three pictures we have have a single venturi one each side of the fuselage rather than two on the right side which was the earlier Cessna solution.

The second venturi might be an "owner-added" modification.

That is true George. I didn't mean to declare that because one '56 picture we have has a venturi on each side and the other two could have a venturi on both sides that all '56s had single venturis on each side. We'd need at least another picture to confirm that.

It was just one of those moments I have when I study these aircraft when I see a pattern and take note of it. When I see that pattern enough I kind of start thinking maybe that is the way Cessna did it. I simply meant to note the venturi locations and maybe we will see a pattern.

So anyone else out there with a '56 with venturis on each side or a ''56 with other than venturis on each side?

BTW this pattern may already be broken as Stephen's '57 has a single 4" venturi on the right and a "2 venturi on the left as far as I can tell from his pictures.

I have serial number 27019 , I think a 1956 model year, with a single venturi on the right side. No obvious signs of any others being removed.

my 172 sn 29406 left the factory on 10/7/1956 with apparently NO venturis (none listed on the original equipment list), as one venturi on each side was added when gyro instruments were installed by 337 on 4/22/1957.

I think it really depended upon what it was ordered with. This airplane was a factory demonstrator until it was delivered to a buyer in March 1957.

HA wrote:my 172 sn 29406 left the factory on 10/7/1956 with apparently NO venturis (none listed on the original equipment list), as one venturi on each side was added when gyro instruments were installed by 337 on 4/22/1957.

I think it really depended upon what it was ordered with. This airplane was a factory demonstrator until it was delivered to a buyer in March 1957.

Venturis were optional equipment on 170s as well. Many were added after the fact. I just saw what I thought might be a new pattern as the 3 '56s we have pictures had just one on the right side (could have had another on the other side). I usually catalogue these observations in my head and only make mention of them if or when I have more evidence. Kind of quickly typed my observation down this time.

oh yeah Bruce, I hear you. I don't even have the right kind of airplane but I figured I'd chip in what I could to the knowledge base. Just happened to have the logs sitting here as I'm in the midst of the annual, so I didn't have to go far to look it up.

Might not matter but Aircraft Kit AK7053-14 shows installation of 2nd venture. Both on right side over top of each other. The documentation is dated 1956.
Mike Roe

The two venturi one side is the Cessna solution. Didn't know the document was dated '56. At convention this year I discovered that the '56 top door hinge was different than all the rest and the same as later years. This exciting discovery I think is why I let my guard down when I saw the '56s with a single venturi I jumped at the thought of another discovery.

My airplane has a venturi on each side, both added in the airplane's early years. Both were 4-inch rated when I acquired the airplane, but I've since switched them out for 8-inch. In the 31 years I've owned '98C I've had occasion to have each one of the venturis be the sole vacuum source. My experience is that the one on the right side works MUCH better than the one on the left to the point that the contribution of the left one is barely noticeable.

Edit: I REALLY DO know my left from my right.

Aryana wrote:Ok Miles you have me confused...which one is more effective? Left or right?

cessna170bdriver wrote: My experience is that the one on the right side works MUCH better than the one on the left - to the point that the contribution of the right one is barely noticeable.

Corrections made! Right side works best...