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Does engine settle over time?

B

bob888

Well Known Member
The spinner in my Cessna has dropped relative to the cowl over time. I am currently trimming the cowl for the -10 and wonder if it should be set below the top of spinner initially. How much, if any?
 
my method

I'm sure you will get a fair number of responses. I don't think there is a defined distance that you should expect the spinner to settle, but it will settle.

My technical counselor had me make an "dummy" firewall, early on in my build, from two 3/4'' plywood panels applied together, to which I mounted the motor mount, Lord bushings and engine. We then let it sit, with the weight of the engine conforming the bushings, while I built on.

Later, I mounted the mount-plus-engine combo to the real firewall as a unit.

While I have had some minor settling, overall I am happy with how this helped the cowl to spinner cosmetics
 
By the time I got to my cowl, the engine had been hanging on the mounts for a good 1.5 yrs. I figured the settling had already occurred although the heat of the engine and general vibration may cause a bit more once it is running. So I believe I set my cowl 1/8" under the spinner. It turned out perfect. Search the forums and you'll get a good number of threads on the topic and you can see the general consensus. Just remember to compare apples to apples. If a guy hung his engine a month ago versus another guy who hung his 3 years ago, the results will be different.
 
My engine was hung about a 8-9 months before working on the cowl. It's been two years since the cowl was finished. The engine has dropped about 1/8" over the two years.

I did anticipate this and configured the spinner so that it was about 1/8" proud at installation. It's now aligned perfectly.

Bob
 
Mine dropped in the first year approximately 1/8". I added a 1/8" shim under the lower mount to compensate for the droop. If I did it again, I would definitely have had the cowl 1/8" below the spinner for the initial fit, or I would hang the engine for some period of time prior to fitting the cowl and spinner. As David stated, they all move!
 
I set my cowl 5/16" lower than the spinner anticipating the engine to sag. I hated seeing that spinner high every time I put the cowl on after that. (Not flying yet) After reading about shimming the engine like others have, I decided to give it a try. Just last week, I loosened the top two nuts on the engine mount just enough to slide a slotted washer I made out of .063 aluminum between the mount and firewall. I put the cowl back on and it was perfect! I torqued and installed the cotter pins and was done. Took a couple of hours. Now, when or if that engine starts to sag, I will replace the washer with a thinner one or take it out.
 
RV 4 engine mounts

I have an older -4 that has old worn conical engine mount bushings that have sagged a lot. I have the engine (0-320- B3A) out for repair and want to put in new Lord mounts, they seem to be well thought of by owners. Can any of you recommend from experience the best ones to get of the following 3 ?
J-6230-1
J-1552
J-9613-40
I definitely will not use the Lycoming rubber mounts again as they sag very rapidly .
Any info would be helpful in deciding which Lord mounts to use.
George
 
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