The Cessna 120-140 Association Forum

Does anyone know what motor mount bolts to use with an O-200 with Lord mounts? Fresno Airparts sells a C-150 O-200 bolt kit with one AN6-43A, one AN6-44A,and two AN6-55A bolts and I'm trying to verify that is correct for 120/140 use as well. I went through the Technical Forum archive but the bolt P/Ns mentioned there are all over the place.

Thanks in advance

I got the same kit, but I ended up using 2 AN6-44As on the lower mounts, probably because I have 2 grounding straps. AN363-624 stop nuts with witness paint. Randy may have a better idea, there is a squish factor on the Lord Mounts.

I have been thinking about this for a while. The question about two different lengths of the 43 and 44 bolts was confusing. Dave answered that question about the ground straps. The only thing that would be concerning about the Fresno Airparts kit would be that some mounts could have different bolt hole length than others. I’ll measure the ones on two of my airplanes and update if they are different.

The 140A parts manual calls for 2 each AN6-44A and AN6-54A. If you're using the 140A mount, I'd expect the O200 to be the same, as it uses the same mounting cushions, etc.

I took a look at mine, and found a few interesting things. I use bolts with castle nuts and cotter pins, and they are a little longer. More like -57 on the upper two. The lower ones are -44’s The ones from Fresno Airparts are probably correct using nyloc nuts. Another interesting thing is that the spacers in the lord Mount kit that Fresno markets are longer that some others that I have removed. Might cause the bolt length to be longer. I find a lot of those spacers squeezed shorter due to over torquing.
Like John said the Mount is the same on a 140A if the engine is a C-90-14. That Mount is also for an O-200A. It is part number 0451111.

Thanks Randy, John, and Dave for the info. This explains the P/N variations I was seeing in the Technical archives. My mechanic prefers we use the castle nuts instead of Nylocs so looks like I'll follow Randy's lead there and use two -57s and two -44s. Hadn't considered the need for a longer bolt to use a castle nut but that makes sense.

Appreciate the help!

6478 wrote: ↑Tue Nov 22, 2022 11:23 pm Hadn't considered the need for a longer bolt to use a castle nut but that makes sense.

If that's the reason, then wouldn't it stand to reason the -44s would have to be -47s, too?

The grip length of a -44 and -44A are the same...

I seem to have two long bolts in the top holes on my c85 and two shorter ones in the bottom. The parts manual shows this configuration for the later serial number planes after 10,000 or so. I assume my mount was changed when they put the Swords motor in, and that is why I have the different top and bottom bolt lengths even though it is an earlier plane.

I swapped all the motor mount donuts today, and was planning to put it all back together, but the bolts themselves had some wear on the shafts at all four locations. I don't know if this is from letting the donuts get too worn at some point in the past or if it is just normal for them to wear at the point that they exit from the motor mount due to the motor jiggling around out there. It didn't feel right to have the only four bolts holding the motor to the airplane with grooves worn into them about halfway around the circumference, so I am ordering new ones.

Anyway the part manual shows
So I guess the uppers are AN6-46 and the lowers are AN6-34.

Does anyone know where can I get some grounding straps-washers 0450148?

Thanks

The bonding strap is just a heavy wire jumper from the engine casing to the engine mount. Easy to make, use #6 or larger wire.

Not sure why you said "bonding straps-washers". There is only one bonding strap and the washers are standard AN960 washers.

[Edit] The bonding strap is important, otherwise your starter current will find it's way down the throttle cable or something similar, and melt/weld it into a useless piece of metal.

[Just one more thing...]If the bolts have noticeable wear, what about the tubes they pass through?