I am the proud owner of an 1858 Cessna 175. I am in the process of installing a O-360 and am in need of an engine mount.

You might need to find a good blacksmith! Tail looks nice; like to see more photos. Sorry I couldn’t be of more help.

What STC are you using? That will dictate the engine mount, unless you can get a deviation approved.

Dave Stoots in Fairbanks, AK has STCs, and presumably can provide parts as well.

Delaire in California also MAY have parts, though I don’t know if they ever approved a 175 conversion.

MTV

I just finished the conversion on my 175, I ended up using a mount off a 1963 172. You can use any O-360 mount for a stepped firewall. I spent nearly two years looking for a 175 mount (literally impossible to find BTW) before I found the 172 mount. PM me and I can give you more details.

Just some observations:

We have two Lyc O-360 converted 175's on field here. N8179T and N8181T (yes, two SN apart). I believe they are different STC's, with the centerline of the crankshaft being noticeable higher (1.5-2 in.) on 81T. 81T I am pretty sure is the AvCon conversion, and with the higher C/L on the crank, puts the prop in a better spot ground-clearance wise and (IMHO) looks better ascetically with the stock 175 cowl lines (top of spinner arc and top of cowl arc being roughly concentric).

I've noticed some variance in the cowl shape on various 175s leading me to suspect that parts changed over the years on the plane. Most noticeably the severity of the "hump-nose" for the O-300 gearbox offset.

I have done some pretty extensive research and comparasins between the various conversion STC’s out there for 175’s (focusing mostly on the older “large mouth” 1958-1959 cowl designs) and have noticed the different output centerline positions seem to vary even within the same STC on the same airframe. Ultimately what I have found is the Del-Air STC seems to typically end up with the crankshaft centerline the highest, and supplied a “scoop” to mod the top cowl with so the aft part of the spinner blended nicely into the top cowl. Many Avcon conversions seem to have the higher position as well, although some are as much as 2” lower than others......

Instructions for the Avcon conversion specifically say to not trim the tow cowl to expose the ring gear but many of them do just this, it could be covered back up with an owner produced fairing I suppose but most I see are left open. Some Avcon conversions have enough clearance on the top cowl to keep the ring gear covered without trimming.

There is a shop in the Minneapolis area that has the Avcon jig and will “repair” a mount if you can provide a piece or part of an existing mount and supposedly charges a little under $2K.

I just completed my conversion using Bob Williams STC and did the whole thing including a CGR-30P engine monitor and overhauling the O-360 (bought it run out) for right about $20K. Using Bobs STC is by far the most cost effective way to go, he only charges $1250 for the paperwork or at least that’s what he charged me in 4Q 2018. Someone on another forum mentioned he is asking $1750 now. Other than that the mount is the only real golden nugget, airboxes can be had or “repaired” easily enough. It took me around 3 years of scrounging deals and searching for parts from the time I decided to do the conversion until it was done, with the work itself taking maybe 2 weeks over the course of a couple months. If I were to do it again I could probably assemble parts necessary in a few weeks. Many of the parts can be fabricated or substituted by more modern, approved alternates like the fuel pump (if using), voltage regulator, instruments, control cables. In fact if you already have of these conversions there are none of those parts available so suitable replacements must be had anyway. You need to be the type that is willing to interpret the drawings in order to complete this conversion, some things are just plain wrong, like the location of the exhaust hole in the bottom cowl. If you do as the drawing says it will be about 1.5” off, so some setup/thinking is involved getting it just right.

Newbizor,
I have a C175 with several stc’s that Bob Williams currently holds. I was wondering the best way to get intouch with him? I’m looking for some supporting documents, including drawings, parts listing and installation instructions. I emailed him and he did get back to me quickly with a question. I answered him and that was the last time that he has responded. That was over a month ago. Have you spoken with him directly? I would really appreciate any info that you may have, a current phone number or anything. He seems like a very difficult person to reach. Thanks!

I have a P172D engine mount, it's for a GO-300 engine. 0550215-8 is the PN. If anyone ever needs it 200 dollars and it's yours. Just throwing that into any 175 conversations. I spoke to an owner yesterday who was glad of anyone parting one out.

Bob’s current e-mail is [email protected]. He will answer you instantly if you tell him exactly what drawing/STC you want and say you are ready to pay. If you are asking anything related to support for a product you already paid him for good luck! From what I hear he usually just ignores you once he gets paid.

Thanks for Bob’s info. I appreciate it!!