Engine Overhaul, Anyone?

I am looking into scratch-building a PA-18. My mission set is quite modest and I don't need the "bush tires and monster engine" solution that works well for many other Super Cubbers.

As an experienced ship builder, I am very much aware of the cost-time-performance iron triangle. The only way I close that triangle on a PA-18 build is for me is if I either luck into a low-time engine just pulled from another plane as part of a power upgrade, or dig in and overhaul a higher-time Lycoming O-290. I've never overhauled an engine, but do have on-call access to auto mechanic friends and sons. The question is this: Am I nuts for considering this part of the project? Do I need to kidnap an A&P? ;-)

Regards,
Alan

Purely an opinion but as a 40 year A&P/IA I have seen some terrible messes come from well meaning non-aviation mechanics that were led into building an engine. it can be done well if you (or they) get hold over the manuals and stick with a basic overhaul. Cylinders will likely need to go to a cylinder shop regardless and needed parts are still a must. I think you would have to choose carefully and stay within the lines to get a good safe engine. Not even all A&P's have any business building up an engine. There are exceptions to everything but the aftermath of an engine gone wrong is long term and double expensive.

If I were choosing for myself, it would be an O-320. The last time I checked on O-290 parts they were pricey and scarce. I like the engine but their day may be past as one to choose.
I have built a bunch of engines myself and was very lucky but I finally learned there are those that build far better engines, get more performance and get it done faster than I I ever could. With all that said, yes I am planning to build my own engine for my PA12, old habits die hard and I have no plan to sell it.
Ken

Thanks Ken. I suppose it is a "fools rush where angels fear to tread" question, but I've kicked around the idea too.

I've overhauled 5 or 6 engines in my lifetime, either as a hobby or by necessity--ranging from a 1938 Buick Dynaflash straight 8, a 3020 John Deere diesel, a Dodge slant six for an old combine, and a V8 Binder (IH). There was a Chevy 292 in there somewhere, too.

Oops, I can't believe I forgot the Audi 2.7 with turbos in a 2001 allroad. That was fun, and hard. It ran great until T-boned by a guy who missed the stop sign in 2015.

They all ran for a long time when I got done, but I'm no genuine gear head. I just followed the specs and the manual.

I was planning on buying a nice new engine, but that was when I was making lots of money. Now I'm back to scratching my head on this.

Ken is right on all counts. And the 290 is NOT the answer. If the manufacturer is no longer supporting the engine...you don't want it. And if your asking this question, you should reconsider.

Overhauling these engines is not rocket science. That said, experience plays a HUGE part in building these engines properly. Not one of these engines are the same and with all the new parts manufacturers building parts for Lycoming and all the PMA parts manufacturers out there stopping and starting....its not like the old days. Everything is different and everything is changing. It takes tribal knowledge to assemble these engines in a manor to allow for proper clearances and longevity. One really needs to know what to look for and if your not doing this day in and day out...your not up to speed.
I recommend you to pick a good shop you trust and or a factory engine if you choose.. in order to have that know how built into your engine. Not to mention warranty.

My $.02

Look for a low to mid time engine from an airplane which was scrapped for reasons other than engine issues. Like a hangar collapse for example. Since you are not in a hurry you have time to wait for the right one.

If your 0-290 case, crank, and accessories are good, why not just bore the case to accept 0-320 cylinders? Seems like that would be the most economical solution.

If you are interested in the O290, call Lycon on Visalia, CA. When I was there about a year ago, they had about 20 brand new, in crates from the Greek AF. They purchased all the stock from Greece a few years back. They told me that if someone wanted an O290, they could come up with a good deal on one. These are the 125 hp, not the -D2. Might be worth a call.
Marty57

$$ adds up fast when you want a good engine my cylinders are at ly-con, case at divco, crank and rods are still here in Maine and may buy a 4-1 exhaust to help my little engine out. so far $350+ in just the shipping to get things where they need to go. Then in a couple of years I will probably want to change out my c-90-8 for an 0-200 (sometimes I probably should listen to the wife) so I can have the convenience of a starter engine cost will be double or more at that point.

John M made me add up my invoices last week. Yuck. I’d rather not know. My thing is if you’re going to do it once might as well send the cyl out, replace the lifters with DLC. Overhaul the carb. The baffles are old, replace them, mags and harness. Just like everything it can snowball.


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I appreciate the inputs. “Tribal knowledge” here in the group as well.

Alan

Marty57 - Does that approach leave enough meat between the new case edges and the stud holes?

Alan

AV8R_1951 said:

Marty57 - Does that approach leave enough meat between the new case edges and the stud holes?

Alan

Click to expand...

I am doing a cub project it cam with a complete 0 -290 . Good pressure baffles carb good air box square.76-52 prop flywheel bendix mags , have front mounted cooler starter and good cowlings and engine mount

AV8R_1951 said:

Marty57 - Does that approach leave enough meat between the new case edges and the stud holes?

Alan

Click to expand...

Yep, plenty of meat. Look at a O-290 case and see how much 'extra' material there is compared to a O-320. Almost like Lycoming designed it with the thought if maybe someday boring it to accept larger cylinders.