O-320 vs IO-320 vs O-360 vs IO-360

[Robert M]

Hi gang!

Does anyone know if there is a difference in the dimensions for the mounts of the engines mentioned above AND if I were foolishly going to weld my own together, where could I get those dimensions?

Dimensions for an IO-540 mount?

Thanks,

Robert

[SHIPCHIEF]

Sure, I'll take a crack at it;
The majority of Lycoming engines available have Dynafocal type 1 mounts. Mount rings with the cups welded on are available at very reasonable cost from Aircraft spruce an other suppliers. You could start with this one and add the rest of the mount.
http://www.aircraftspruce.com/catalo...clickkey=24310
Older engines, no longer in production, and engines made for some helicopters use Conical mounts, a simpler system to weld up yourself.
The Dynafocal Type 2 is fairly rare, I think only found on IO-320 engines made specifically for Piper Twin Comanche aircraft. The focal point of the mount bolts is farther forward than the engine's center of mass due to the Comanche using an extended hub propeller? You may have to make your own ring and cups for this one? Or perhaps the dynafocal kit with the cups not welded on accommodates this alternate mount.
Hopefully I got that right..

[jrs14855]

The Twin Commanche engines were IO-320B and IO-320C series engines. All four cylinder Lycomings with type I mounts, 0 235 thru 0 360, will fit the same engine mount.
If you intend to make your own ring both Pitts and Skybolt(or maybe Starduster) plans show details on jigging and building the mount ring.

[sstocker31]

You should just go to ebay and buy a mount with the correct ring you need. Then cut off the mounting bars and weld on what you need.

[Sam Staton]

Original RV6 plans have an extremely detailed drawing of both conical & Dynafocal mounts.

[Robert M]

Thanks for the info gang. This is all just research for a friend that is determined to scratch build (and I mean everything) a Skybolt from plans. He hasn't decided on which engine (360 or 540) to put in it. He's just finished cutting the wood strips for the wing ribs so he's a long way from the engine decision.

Thanks again,

Robert