I've got a '54 Cessna 180 which contains the dreaded O-470-A engine. The plane hasn't been flown in about 10 years, but the engine starts and does a run-up just fine. It only has 400 hours since its last major overhaul. The compressions, however, aren't anything to write home about, but I know that doesn't necessarily mean that the engine is trash.

I'd like to avoid swapping out the engine. I've heard that it isn't worth it to put any money into this engine, but I've also heard that it's not such a crazy idea to give it a good check-up, and possibly a top overhaul. I can't help but to think that with such a low-time engine since overhaul that it can be resurrected. All I'm trying to do at the moment is get this plane going again.

Thoughts? Suggestions?

What is the calendar time since the last major overhaul? What did this major overhaul consist of according to the aircraft record? What environment was the aircraft in during this prolonged storage?

These are some major variables

If the lower end doesn't have any corrosion, I'd say that engine is worth saving.
It might be that soaking the top with mystery oil, and/or just running it some,
will bring the compressions up to an acceptable level.
Otherwise, assuming a good lower end, you can overhaul the cylinders --
or maybe just hone & re-ring if the compression leakage is all going by the rings.
I believe the 470A used 3 ring pistons, there's an upgrade to 4 ring pistons which is supposed to decrease oil consumption.

The A engine (and to a lesser extent, the J) gets badmouthed a lot, but I know of people still happily running them.
They are quite a bit lighter than the angle valve engines--
the W&B records for my 53 C180 shows 26 pounds difference going from an A to a K.

On top of the cost of the engine itself,
upgrading to a K or later engine will involve making some changes to accommodate it--
the engine mount & exhaust are the main things.
And quite likely a different prop will be needed or at least desired.

The 470U I am converting to a Pponk right now was on the 180K I purchased. Supposedly it sat in a hangar around Sacramento CA for 25 years until 2015 when the mechanic I purchased it from bought it and did some things. Other than pulling the front left cylinder to check the camshaft for corrosion, the engine was untouched with 1000 since major and 600 since top.. I bought it,upon delivery, and figured if it made the 800 mile trip it might be sorta okay. I flew it around for 20 hrs and it actually ran like a top with high oil pressure and didn't use much oil. But, the oil turned black almost immediately after changing. I did a compression test and all were in the 40's. I had my other Pponk by then so made the swap. The crank and case were good and I assume most of the other parts are okay for my current conversion. Just my experience. I had an "A" that I should never have taken apart. It ran great but the rocker arm bushings wore thin in no time after a top. Turns out the springs were too strong. I found that out later.

RSPerk wrote:I've got a '54 Cessna 180 which contains the dreaded O-470-A engine. The plane hasn't been flown in about 10 years, but the engine starts and does a run-up just fine. It only has 400 hours since its last major overhaul. The compressions, however, aren't anything to write home about, but I know that doesn't necessarily mean that the engine is trash.

I'd like to avoid swapping out the engine. I've heard that it isn't worth it to put any money into this engine, but I've also heard that it's not such a crazy idea to give it a good check-up, and possibly a top overhaul. I can't help but to think that with such a low-time engine since overhaul that it can be resurrected. All I'm trying to do at the moment is get this plane going again.

Thoughts? Suggestions?

I would do the following:

1. Change the oil.
2. Inspect the cam & lifters. Inspect cylinder bores. Replace any lifters showing corrosion.
3. Inspect the counterweights with a borescope for corrosion.
4. Run 10 hours and do oil analysis baseline. Compression check and cylinder borescope.
5. Run 15-20 hours and do another OA & compression.
6. Run 15-20 hours and do another OA
7. Inspect cam/lifters at 75-100 hours.

I just got a 170 going that had not flown in 15 years. Luckily, it has chrome cylinders.