Seeking guidance on C85/O-200 crank STC

Ask Questions and Offer Advice Related to the Cessna 120 & 140 Type

Moderators: 6643, 6183, V529

Forum rules
You must be a member of the Cessna 120-140 Association in order to post new topics, reply to existing topics, or search for information on this forum. Use the "Join" link in the red menu bar.
4945
Posts: 42
Joined: Tue May 01, 2018 7:00 am
Location: Stockton, CA
Name: Gary
Aircraft Type: C-120
Occupation-Interests: Retired Congressional Staff, Navy Reserve Retiree, Former P-3 Flight Engineer, Former aerospace technician
Contact:

Seeking guidance on C85/O-200 crank STC

Post by 4945 »

My C85 crank failed inspection at Aircraft Specialties for a cracked flange. I've found a recently overhauled 0-200 crank that will require the STC to use in my C85. I'm working with an A&P with engine overhaul experience.

For anyone who has done this, is there anything I should be aware of before spending the big bucks to acquire this crankshaft? Anything specific to the Aircraft Specialties STC? Are there limitations on which part number is applicable? (this is the old 530182)

Gary Prost
Stockton, CA
tonycondon
Posts: 71
Joined: Thu Oct 01, 2020 11:02 am
Location: Wichita, KS
Name: Tony
Aircraft Type: C-120
Occupation-Interests: Pilot, CFI, DPE
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by tonycondon »

Aircraft Specialties should be able to answer those questions. Congrats on finding a good crank. I'm on the waiting list with them to get a new one...
N2395N
6298
Posts: 242
Joined: Tue May 01, 2018 7:00 am
Location: California
Name: Randy Thompson
Aircraft Type: Cessna 140
Occupation-Interests: Work on airplanes and engines
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by 6298 »

You will need O-200 Rods and Pistons with the O-200 crankshaft. There is a quarter inch more stroke and the C-85 rods won’t fit the O-200 crank.
Randy Thompson A&P IA Pilot
Hold STC SA547EA for installation of O-200 engine in Cessna 120/140 and 140A"s
Overhaul small Continentals
V529
Posts: 552
Joined: Tue May 01, 2018 7:00 am
Location: Michigan
Name: Victor G
Aircraft Type: C-120
Occupation-Interests: Work on airplanes till the cows come home..........they're still out.
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by V529 »

The STC costs money, but in the end it will be worth it.

A replacement crank, (Aircraft Specialties can answer questions, as I recall it's their STC)
You will need the case worked for the changed front bearing as I recall. And the parts mentioned above.

You will gain about 5-10HP.
6930
Posts: 130
Joined: Tue May 01, 2018 7:00 am
Location: Illinois
Name: Mike
Aircraft Type: C140
Occupation-Interests:
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by 6930 »

Did my engine with the O-200 crank in 2011 including 4 new ECI nickel carbide cylinders. It was a great investment and I’m glad I did it.

Definite HP increase. Judging by before and after static run up RPM, I estimate 14 HP total increase using the power curves for the C-85 with some of that (guessing 4 or 5?) from having new cylinders, the rest from higher compression and increased displacement with the O-200 pistons and crank.

Over 1,000 hours since the overhaul and I’m climbing at 2425 RPM, fully loaded at 70 MPH.
Mike Pastore, N2635N
Naper Aero, LL10
tdragger
Posts: 17
Joined: Sun Jan 24, 2021 7:30 am
Location: Indian Mound TN
Name: Dennis M
Aircraft Type: 1946 C140
Occupation-Interests:
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by tdragger »

I have the STC on my engine and just put a new Top on it. The downside was when ordering the new Millennium cylinder kits from ASS they came with the C-85 pistons. I could not substitute and had to purchase the 0-200 pistons separately. Sold the C-85 pistons so that helps.

Also note in the STC text about the different timing settings for each magneto.
User avatar
6643
Posts: 2326
Joined: Tue May 01, 2018 7:00 am
Location: KLCI
Name: John C
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by 6643 »

6930 wrote: Tue Aug 30, 2022 9:30 amI’m climbing at 2425 RPM, fully loaded at 70 MPH.
For a minute there I thought it said "2425 FPM"
6930
Posts: 130
Joined: Tue May 01, 2018 7:00 am
Location: Illinois
Name: Mike
Aircraft Type: C140
Occupation-Interests:
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by 6930 »

Well, you’ve heard of Super Cubs…..mine is a Super 140 😂
Mike Pastore, N2635N
Naper Aero, LL10
6930
Posts: 130
Joined: Tue May 01, 2018 7:00 am
Location: Illinois
Name: Mike
Aircraft Type: C140
Occupation-Interests:
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by 6930 »

tdragger wrote: Tue Aug 30, 2022 12:36 pm Also note in the STC text about the different timing settings for each magneto.
Very true....however the standard timing for the C85 is 28R/30L BTC. The timing for the Aircraft Specialties STC 0-200 upgrade is 27+/-1 R and 29 +/-1 L.

I have my mechanic set the timing to the original 28/30 which is within the STC tolerance. The advanced timing makes my airplane climb like an Atlas V rocket unless I've had too much pizza the day before :D
Mike Pastore, N2635N
Naper Aero, LL10
edidin
Posts: 139
Joined: Mon Jul 19, 2021 8:57 pm
Name:
Aircraft Type:
Occupation-Interests:
Contact:

Re: Seeking guidance on C85/O-200 crank STC

Post by edidin »

6930 wrote: Tue Aug 30, 2022 8:47 pm
tdragger wrote: Tue Aug 30, 2022 12:36 pm Also note in the STC text about the different timing settings for each magneto.
Very true....however the standard timing for the C85 is 28R/30L BTC. The timing for the Aircraft Specialties STC 0-200 upgrade is 27+/-1 R and 29 +/-1 L.

I have my mechanic set the timing to the original 28/30 which is within the STC tolerance. The advanced timing makes my airplane climb like an Atlas V rocket unless I've had too much pizza the day before :D
Does anyone know if the STC timing is consistently 27 ± 1 R and 29 ± 1 L across the various holders of the STC?
Post Reply

Who is online

Users browsing this forum: Google [Bot] and 19 guests