Throttle body bore diameter?

[skylor]

Originally Posted by DanH

The standard horizontal sump should be 2-5/16", like the RSA-5. The "cold air" manifold on the 390C and D is sized for an RSA-10.

That’s interesting about the 390 C/D sump. Unless Lycoming used a different casting than the IO-360A sump, it doesn’t look like there’s room inside the sump to increase the bore 1” or so in diameter:


Skylor

[DanH]

Originally Posted by skylor

That’s interesting about the 390 C/D sump. Unless Lycoming used a different casting than the IO-360A sump, it doesn’t look like there’s room inside the sump to increase the bore 1” or so in diameter:

Same as the 360A. Ask Ron Moring about enlarging the flange. Apparently it can be increased enough to eliminate the adapter normally used to mount an FM-200, bore size 3-1/16". May not be able to fit an RSA-10.

It helps that the FM-200 bolt pattern is rectangular, 3.12 X 2.82. The RSA-10 bolt pattern is 3.375 square. Sketch below is to scale.

Beyond that, I dunno. Have not done it myself...but I'd like to.
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