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Advice needed: Overhauled engine Kit a good idea?

tom paul

tom paul

Well Known Member
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I have an opportunity to buy an overhauled, yellow tagged A1B6 core kit, nothing assembled, for $20k. It has four new cylinders and a replacement "overhauled" cam, including some accessories. (list below) I don't know enough to be able to inventory the parts. Is this a good price, and would it make sense to hire an AP local to the engine parts to inventory everything? Any idea how much it would cost to have this engine built? I would use what I could from my IOX360 H4A1N to complete the accessory package, including intake and exhaust if possible.
Does this make sense? And is the heavier A1B6 with 200HP a good candidate for my RV7A? I like the idea of 12 more HP, and a smooth counterbalanced crank, though I was never objecting to the vibration in my plane.

Accessories included,
Bendix Fuel Injection Servo, distributor and lines
New Cylinders
Bendix Mags and Harness
Mechanical fuel pump
Oil Sump and Tubes
Prop Gov Drive

Additional Parts Included:
New Rod Bolts
New Oil Pump Gears
Vernathurm
New Tack Drive
Starter SkyTec 149/12PM
 
I'd need to know more about your money situation and values to answer this.
Others might have more informed opinions.
I value engines built in recognized factories way more than something that might work.
 
RNB said:
I'd need to know more about your money situation and values to answer this.
Others might have more informed opinions.
I value engines built in recognized factories way more than something that might work.
Click to expand...
Well, I bought the plane on a HELOC, so one could say I am living beyond my means. Having a good time though. I value correctness, precision, and safety!!! That said, I don't stand on principle and I am open to thinking outside the box.
 
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I can only speak to your weight question:
Yes, it is worth the extra weight. I had one on the -7A that I built and it was fantastic. With a lightweight composite prop it will be amazing.
The extra HP comes without high compression pistons and their worries.
Actually, I can speak to the overhaul cost, too: If you can build a plane you can follow the Lycoming overhaul manual and do your own IRAN. The case, crank, and accessory gears will need to be sent out for yellow tag. I can’t say whether $20K is a good deal in the package you are looking at. But any core package is a much better deal if you assemble it yourself.
 
andoman said:
I can only speak to your weight question:
Yes, it is worth the extra weight. I had one on the -7A that I built and it was fantastic. With a lightweight composite prop it will be amazing.
The extra HP comes without high compression pistons and their worries.
Actually, I can speak to the overhaul cost, too: If you can build a plane you can follow the Lycoming overhaul manual and do your own IRAN. The case, crank, and accessory gears will need to be sent out for yellow tag. I can’t say whether $20K is a good deal in the package you are looking at. But any core package is a much better deal if you assemble it yourself
Click to expand...
Thanks for your thoughts. it is already yellow tagged and ready to assemble. I didn't build this plane, but I have overhauled 356 porsche engines 30 years ago and I am comfortable following instructions.
 
It depends on if you have the skillset to put all this together. Is the crankcase and crankshaft yellow tagged as well? It has the bearings for the crank and rods as well, that are the correct sizes for the grind on the crankshaft? 20K is not a bad price if all the parts are there. Building engines is just like building a airplane. You get some help who knows what there are doing and you take your time and go through the steps. If you have the right tools to do also helps. You want to make sure you properly record the critical specs/tolerances. The 200hp is a little more complex with stretch bolts on the connecting rod bolts, counterweight rollers and snap rings, prop governor drive gears up front. IF the overhaul company is a reputable place, then don't be scared by items like the cam being overhauled. In fact, a lot of the parts in aviation after covid, seem to be of lessor quality than parts of old. Camshafts seem to be going out a lot sooner on these newer cams versus the older ones. Don't know what is exactly the metalurgy from the past compared to the new ones. I've seen cams going T/U in like 200 hours. I've had some cams that I got out of old engines that sat for 25-30 years and they were not rusted and they were serviceable. Storage conditions play a part but it makes you wonder......
PM me if you need more help identifying what you got.

Aden
 
Tom, an awful lot depends on how much you trust the folks who did the yellow tagging. And do you have the ability to check them? For example, let's assume some case shuffle, i.e. fretting between the mating surfaces at the bearing bores. It would typically go to a good case shop who would skim the mating surfaces on a mill and re-bore the journals. Note three fundamental questions...did it need it, was it done, and was it done right?

Four new cylinders is a big deal, but are they Lycoming or something else? Recent Superior cylinders might let some air out of the deal...

The "counterweights" are actually pendulum absorbers. They don't add smoothness you would feel in the cockpit. Their purpose is reduce the amplitude of crankshaft torsional vibration, typically sixth and eight order. Eighth order at 2400 RPM is 320 hz. Combustion events for a 4-cyl would be 80 hz, while ordinary rotating balance would be 40 hz. Mostly the pendulums make life easier for a constant speed prop, a great big tuning fork which might resonate the tips at the higher frequencies.
 
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