C85 Conversion Complete!

[Kerbs]

Well it took three and a half months but N96234 is now re-powered with a zero time C85. Through the process everything firewall forward was replaced/rebuilt/overhauled. Ultimately I ended up with a C85-12 on a short mount, McCauley 1B90 7148, Luscombe 8E Exhaust, Marvel carb, Bendix mags, shielded ignition using cups, and a zero time tach. I did not add a starter or alternator as part of the upgrade as I wanted to stay non-electrical. While I was doing the work I also replaced my old Narco elt with a 406MHz unit. We fired it for the first time yesterday and it ran smooth as butter. I will hopefully get to ground running and test flights this week weather providing.

What I learned from the experience (and my first repower/upgrade on a plane) was: 1) It takes time to find things, you can speed this up with more $$ but it just takes time to source a good engine and parts. 2) It will ultimately cost more than you think it will. 3) There was a lot of time spent researching and learning. Tracking part numbers takes time, reading old diagrams takes time, and generally everything takes time if you are learning as you progress.

The upside to doing most the work myself with my IA's support is that I now intimately know and understand the workings of the engine and the plane.

Thanks to the help on this board and fantastic archive of information that allowed me to answer many questions by doing a little searching. Terry was also very supportive of my questions on the STC through the process.

I have a pretty good breakdown of cost I can provide if it's helpful for those considering it.

[astjp2]

Well it took three and a half months but N96234 is now re-powered with a zero time C85. Through the process everything firewall forward was replaced/rebuilt/overhauled. Ultimately I ended up with a C85-12 on a short mount, McCauley 1B90 7148, Luscombe 8E Exhaust, Marvel carb, Bendix mags, shielded ignition using cups, and a zero time tach. I did not add a starter or alternator as part of the upgrade as I wanted to stay non-electrical. While I was doing the work I also replaced my old Narco elt with a 406MHz unit. We fired it for the first time yesterday and it ran smooth as butter. I will hopefully get to ground running and test flights this week weather providing.

What I learned from the experience (and my first repower/upgrade on a plane) was: 1) It takes time to find things, you can speed this up with more $$ but it just takes time to source a good engine and parts. 2) It will ultimately cost more than you think it will. 3) There was a lot of time spent researching and learning. Tracking part numbers takes time, reading old diagrams takes time, and generally everything takes time if you are learning as you progress.

The upside to doing most the work myself with my IA's support is that I now intimately know and understand the workings of the engine and the plane.

Thanks to the help on this board and fantastic archive of information that allowed me to answer many questions by doing a little searching. Terry was also very supportive of my questions on the STC through the process.

I have a pretty good breakdown of cost I can provide if it's helpful for those considering it.

good work, please post pics of the installation! Now how does it fly?

[Kerbs]

I just completed the first test flight late this afternoon. It had been run in previously for 1.2 hours on the stand. I flew for another 0.6 and made a total of 4 landings. First off, it definitely gets off the ground a lot faster. The shielded ignition was a wonderful improvement, I cant believe I waited to do it. I was a little surprised with the 71-48 to only turn just above 2,100 static when we had it tied up. I originally wanted a 71-46 as i am looking for climb performance but found too good of a deal on this prop to pass it up. If I understand correctly I would only get another 60 rpm or by going down two inches. Level flight I could make just above 2,400 rpm. I am thinking I may benefit from a steeper pitch prop.

That being said, it jumps off the ground compared to the A65. Throttle response is almost instant with the new marvel carb and having an accelerator pump. Before with the stromberg, I would have to really ease it in on touch and goes.

So far and one flight in I am really happy with it. I'd love others input on prop or what they are turning for RPM. I don't have much of a baseline to work off of.

[N96337]

Congrats!!! Glad you like it! Mine had a 71-46 when I got it and that's listed as cruise, so I took it to the prop shop and helped them flatten it out to a 71-42 and that was what they had listed for seaplane. It was a night and day difference in takeoff and maybe 5mph difference in cruise.
Have a blast Kerbs!! It looks great!!!
John

[astjp2]

I just completed the first test flight late this afternoon. It had been run in previously for 1.2 hours on the stand. I flew for another 0.6 and made a total of 4 landings. First off, it definitely gets off the ground a lot faster. The shielded ignition was a wonderful improvement, I cant believe I waited to do it. I was a little surprised with the 71-48 to only turn just above 2,100 static when we had it tied up. I originally wanted a 71-46 as i am looking for climb performance but found too good of a deal on this prop to pass it up. If I understand correctly I would only get another 60 rpm or by going down two inches. Level flight I could make just above 2,400 rpm. I am thinking I may benefit from a steeper pitch prop.

That being said, it jumps off the ground compared to the A65. Throttle response is almost instant with the new marvel carb and having an accelerator pump. Before with the stromberg, I would have to really ease it in on touch and goes.

So far and one flight in I am really happy with it. I'd love others input on prop or what they are turning for RPM. I don't have much of a baseline to work off of.

Get the longest and flattest propeller you can get, I ran a 7443 with a o-200, I started with a a 7446, I gained a lot of climb and it can cruise 105 kias with the last prop I had. I am not sure what my current one will do as a swapped from a Sensenich to a McCauley. The marvel carb is also great because of having a mixture.

[Mike S]

Looks good, Kerbs, it took me about that long just to have new tie struts welded in and gear reinstalled. An engine swap might take me three years!
What's been learned so far: I need one aircraft fueled up and ready to fly and another one in the hangar/shop ready to be tinkered with.

[Jim Herpst]

Kerbs, What model Marvel did you use? Does anyone know if the stroker 85 takes the same Marvel as the stock 85? Or the O200 Marvel allowed/work?

[astjp2]

There is only 1 model marvel/tempest carb approved for the 85, even it it has an o-200 crank, it is still an 85. There is an STC that will allow you to use an O-200 carb on an 85 if you install certain parts into it, basically making it an 85 carb, using the 0-200 body, but that is the only exception that I have found.

[Jim Herpst]

What is the number of the Marvel/Tempest carb approved for the 85?

[astjp2]

https://msacarbs.com/product/ma-3spa-carburetor-10-4240-1/

[Jim Herpst]

Thank you

[N96337]

Holy buckets, for that money my Stromberg works just fine!!!
John

[astjp2]

Holy buckets, for that money my Stromberg works just fine!!!
John

You say that up until your engine conks out on short final when you push the throttle in trying to do a go around and all of a sudden you are committed no matter what you want to do...and a Stromberg will cost you about 950 to overhaul your carb from a certified shop.

[Kerbs]

That is the same model I installed. I was unable to reuse the stomberg as it was the B model only certified for the A65. Regardless, I was due for an overhaul and it made sense to go with the Marvel. Having the accelerator pump and throttle response is awesome.

[Kerbs]

For what it's worth, core value for the Stromberg is about $300 when exchanging for a marvel. I was lucky to have a buddy with a marvel core laying around.