The International Cessna^® 170 Association

I am in the process of searching for a 170B to purchase. The research I have conducted established that there are a number of different engine variants in use in the 170 fleet. I am interested in opinions regarding the Franklin 220 HP engine. I have heard from Stinson drivers that the Franklin might not be the best engine. Appreciate your opinion.

We also have a Stinson 108 with a 165 Franklin Engine. The 108 out performs the 170 with this engine. The Franklin needs to be taken care of and is not an engine you just add gas, oil and go between annuals. It needs to be maintained (15 to 20 hr oil changes, plug maintenance, etc) and if done so it is a smooth and relaible engine.

The original Franklin engines were good engines in their day, the problem is supportability. Parts and expertise are getting harder to find these days (as compared to the TCM engine.)
The 220 hp Franklin was a newer design mfr'd/cert'd by the Czechs, and re-marketed by a few U.S. companies, (one in Colorado, one in Texas, and one in Florida) and is no longer in production (as is the original TCM engine.....however the original C145/O300 was produced in such large quantities that parts availability is far better than any Franklin, and is likely to remain so.) Although Pratt & Whitney purchased the mfr'g rights (as part of a package deal in order to acquire a turbine engine design), they have no plans to produce the reciprocating engine. Therefore the engine has no FAA approved production certificate and can no longer be mfr'd. Unless someone bellies-up-to-the-bar with big bucks to purchase that TC and get a production certificate from the FAA....the 220 hp Franklin will pass the same way as the older engines. Our assn. has a member who has experessed an interest, and I visited with him in Wilmington at the convention about it, but it does not look good.
Is this a problem? It depends upon your long-range plans for the airplane (and whether you feel lucky about finding parts in case of a short-term failure of some sort.)
An engine conversion to upgrade horsepower in a 170 from the original engine costs about $30K+. Taking an upgraded airplane over to a different conversion would likely cost the same. Taking one BACK to original may cost less than that, but it is probably a consideration I'd want to evaluate before I purchased an airplane with a Franklin engine conversion. Alternatively, I could hope for good luck that I'd not suffer a catastrophic failure or a dibilitating AD note against the engine, and just let my heirs deal with it.
(Now, there's a thought. What if the 220 Franklin came out with a crankshaft AD note against it a couple years down the road?)

The 220 Franklin is the smoothest engine I've flown behind thanks to the self balanceing part of the flywheel. And a massive amount of power! It's a very old designed engine and assembles a little weird. I rebuilt one for a Stinson I had. The 220 has a 10:1 compression ratio which is a little high for my taste.

Before you buy one be sure it has had a full flow oil filter since new. Without it's a 750 hour engine especially if AD oil has been used. The design was pre-AD oils and it has a floating pickup for the oil to the pump. When used as designed with non-ad oil it would just collect the dirt in the pan. With AD oil particles will just keep circulating without a filter.

I really like my O-360 Lycoming.