The Cessna 120-140 Association Forum

I have a C-90-14F engine to install on a 140 plane that previously had a -12F engine. The current installed engine mount is the 0451000. I see per the A-768 TCDS, note 5 that I need a (0451111) different engine mount. The note 5 mount has an addition diagonal brace presumably for a higher horse powered engine?? The -12F and -14F have the same horse power but I think the -14F weighs 4 more pounds. I also see the -14F uses different mounting hardware, than the -12F hardware.

Is there a conversion/adapter STC (or 337) out there that would substantiate putting the -14F engine on the 0451000 engine mount? If so can someone steer me to it??

Thanks

The -14 engine uses the same engine mounts as the O200, called "Lord Mounts". The -8 and -12 use the "conical" mounts. The Lord mounts extend back about 1/2 inch farther from the engine case than the conical mounts, so, unless you change the mount your engine will be about 1/2 inch further forward and interfere with the cowl. I'd be interested to see how your installation accommodates the difference.

The additional tube in the 0451111 is to accommodate the additional power of the O200.

Lord mount is on the left.
There are adapters you can get to allow the -14 case to use the -12 conical mounts. Their airworthiness is questionable... I would say a field approval would be required.

I suspect you may do more damage than good by trying to find a "conversion" isolator. I realize the cost of the new mount and the Lord isolators are substantial, but not having good isolators, that properly fit and support your engine could cost the price of an engine case (and complete tear down) sometime in the future. Personally, I wouldn't even consider it.

Thanks for all the words of wisdom.

I went forward in getting the 0451111 "proper" mount ( for the C90-14F engine I have). There is indeed a 1/2 inch difference in station value. See attached photos 0451000 mount next to the 0451111. I placed a level on two of the mount pads common to the "taller" 0451000. I extended the level over one of the same pads on the "shorter" and used a scale to show the difference.

I came across a used a set of a " conversion isolators " to install the -14F engine I have on the 0451000 mount. I could not find any substantiation data to present on a 337 and was not confident in the vibrations I might encounter. So I gave up on the idea.

Photo three shows the adapters I was referring to. I recall that Don Swords had some sort of approval for them, but I could be wrong.

Im not familiar with the C-90 but there is a difference in the position of the cast flanges on the engine case between a C85 and an O-200. You need to add this in your analysis to be sure the crank flange is in the right spot. As i recall, it’s about 1/8” offset, which adds into the stack up. Perhaps the machined adaptors take this in to account. There is so little clearance up front, though, it makes a difference.

Good luck

FWIW department, an old A&P I knew suggested that the mounts for the C90 and 0-200 had a degree or two to the starboard built in compared to the C85 mount. My lower '46 cowling seems to hug the starboard side of the airfilter with my 0-200. Don't know how true that is or not....