Since the 170 site is down do any of the 170 pilots know what the cost of the STC is that is required to put a O-300D on a 170B? Thanks

I installed one on a field approval a few years back. I think I still have a copy of it if you are interested. The only difference in the D compared to the A is the prop flange and provisions for the vacuum pump on the back of the starter drive if I remember correctly.

Dave

I found the STC that is owned by the 170 forum. Is the flange difference the 6 hole vs the 8 hole? Do you know if you can change the flange? I would hate to have to go to the older 1C172EM prop from what I have MDM. Any issues going from the O-300A or was it a C-145? Do you have an electronic copy you could PM me with? Thanks!

If you were OH'ing a D engine, you cold probably get some sort of approval to install a C-45 or O-300A crank with the 8-bolt flange. But, usually it's the other way around-- people are installing 6 bolt cranks in the 145/300-A engines when they can't get their original crank yellow-tagged, and can't find a replacement 8 bolt crank. They're getting kinda scarce, and therefore real expensive when you can find them.

Eric

The International C 170 Association (TIC170A) owns the STC to install the O-300D in the C-170 series airplanes. Join the association and get it from them.
The principal difference between the earlier engines and the D series is the starter and starter drive mechanism. They do have the six bolt prop flange.
The crankshaft from the Continental IO-360 engine is used as the replacement crankshaft for the O-300 series engines. It is also a six bolt flange.