IO-320 Twin Comanche engine mounting

[ohtonentr]

I am building an RV-9. I purchased an IO-320 Twin Comanche motor and I am trying to attach the motor to the engine mount. However the rear case of the engine where the lord mounts rest has a flange which will not let the lord mount sit at the correct angle. I was hoping that someone has run into this problem and has a fix or solution for it.

[Ralph Inkster]

I think Twin Comanches used Dynofocal2 engine mounts & your 9 mount is Dynofocal 1.
A few options;
- inquire at an engine shop if your engine can be converted to a Dynon 1 setup.
- see if Vans can swap your mount for a custom ordered Dyno 2 mount
- check with a local aviation weld shop about modifying (cut & splice) your existing mount
- anybody think of more options?
Nothing as bit of time & money can't solve.

[Mel]

Just as Ralph says, that engine requires a Dynofocal II mount.

You may also have a problem when fitting the cowling, depending on what type of induction you have.

[spark68]

I'm told that Crankcase Services in OK can modify the engine cases from Dyna II to Dyna I for a few hundred $.

I have a similar (same?) engine and have that step ahead of me. Seems like the lowest cost option, but requires an engine tear down (which I have to do anyway). Puts the engine to the "standard" Dynafocal I.

If you weren't planning on a tear down, maybe the custom engine mount would be cheaper?

Good Luck,

Mark

[N130PM]

Originally Posted by ohtonentr

I am building an RV-9. I purchased an IO-320 Twin Comanche motor and I am trying to attach the motor to the engine mount. However the rear case of the engine where the lord mounts rest has a flange which will not let the lord mount sit at the correct angle. I was hoping that someone has run into this problem and has a fix or solution for it.

You need to put in the inserts. There are inserts that go into the case that make it all mesh. I ran this same motor and it was great. I called Don George in Orlando and he had a shoebox full of the inserts. You don't need to modify anything. It's a great motor.

[rvbuilder2002]

Originally Posted by N130PM

You need to put in the inserts. There are inserts that go into the case that make it all mesh. I ran this same motor and it was great. I called Don George in Orlando and he had a shoebox full of the inserts. You don't need to modify anything. It's a great motor.

Correct.... you don't have to modify anything on the engine if you have a type2 dynafocal engine mount.
If you have a Type 1 mount and you do not want to get a type 2 mount, having the case modified to a Type 1 is the only option.