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I've found that the Cessna parts catalog must be used in conjunction with the C85/C90/O-200 parts manual to come up with the correct sequence for mounting the engine. While removing my engine for overhaul I found that the previous mechanic(s) had done a slipshod job of mounting it, using totally different hardware on different mounting points- a really crummy job, frankly. I'm wanting to put it back together the RIGHT way. So I created this little sequence diagram using what I deduced from the parts books. I am wondering if perhaps those of you in the know could confirm whether this looks correct just for some added peace of mind? This is based, again, on a combination of the parts manual for both the engine (mine is a C90-12F) and the 1947 Cessna 140. Does this look right? PS- I know the engine grounding straps are missing, and it's not perfectly top scale. I created it as more of a sequence guide...
Thanks to all...
Engine-Mount-Bolt-Sequence_fin.png (14.17 KiB) Viewed 1370 times
Where you are showing the AN970-6 is actually where the bolt passes through the engine mount, between the AN960-616 and the 22387 bushing. The forward face of the mount has a washer welded in place, so there is no wide area washer called for on the back side of the engine.
Cessna did not specify the 21530 engine washer, a Continental part, but rather two AN960-6 washers, which explains why the parts list calls for 8.
The AN310 nut is a tension nut and your drawing appears to show a shear nut (AN320).
6643 wrote: ↑Tue Jun 16, 2026 7:37 pm
Where you are showing the AN970-6 is actually where the bolt passes through the engine mount, between the AN960-616 and the 22387 bushing. The forward face of the mount has a washer welded in place, so there is no wide area washer called for on the back side of the engine.
Cessna did not specify the 21530 engine washer, a Continental part, but rather two AN960-6 washers, which explains why the parts list calls for 8.
The AN310 nut is a tension nut and your drawing appears to show a shear nut (AN320).
I was confused about that AN970-6.
That's so interesting about the 21530 washer. Why does Continental show it in their C90 parts catalog but Cessna doesnt? Does the Cessna parts manual take precedence in that case?
That last one (the castle nut) I knew I'm just lazy and grabbed that from the internet so I didnt have to create one from scratch.
As always, thanks John. You're a wealth of useful information.
Continental says 60-80 inch pounds without the spacer. There is no torque spec for "with the spacer". For the Lord mount, which has a spacer that is much heavier than the Cessna one, Continental says 180-190 inch pounds but that may be enough to deform the Cessna spacer.
Based on John's comments (and reviewing the Cessna parts book, I have re-drawn the proper hardware sequence for mounting the C90-12 on the engine mount. This is for future reference in case anybody needs it. Thanks for everyone's comments.
Engine-Mount-Bolt-Sequence2.png (15.35 KiB) Viewed 1203 times
Not to diminish Marc's hard work in any way, but, here is the drawing from the Continental Manual section on installation. Note they spec a "spacer", really an AN970-6 washer, quantity "as needed" to adjust the CG of the engine. The Cessna spacer is noticeably absent. Also, the washer on the front of the engine lug is spec'd at 3/32" thick. One AN970 is 1/16" thick.
Continental cone mount.jpg (122.39 KiB) Viewed 1161 times
I'm just lazy and grabbed that from the internet so I didnt have to create one from scratch. 