sansoneservices
Well Known Member
The Lyc IO-360 angle valve crankshaft can be had with or without dynamic counterweights. I assume the crankcase is different for each. Anyone know?
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IO-360 with counterweights question
- Thread starter sansoneservices
- Start date
No first hand knowledge, but vaguely remember that the weights were opposite the crank offsets and didn’t increase the area required in the crankcase. My guess is that they fit in the same case. Too many years ago when i had the 540 apart.
Should be able to figure it out by reviewing parts catalogs.
Be careful with weight and pin parts, as they are usually specified based upon the prop hub type and the to the sub model. A few varieties out there.
Should be able to figure it out by reviewing parts catalogs.
Be careful with weight and pin parts, as they are usually specified based upon the prop hub type and the to the sub model. A few varieties out there.
sansoneservices
Well Known Member
Yes regarding the specific weight configuration. Lycoming has a tech service bulletin regarding. I'm going to open the IPC and determine cases. I came across a high time engine with the B6 suffix, the 6 means weights. Thanks for response
sansoneservices
Well Known Member
Thanks muchly sir.. I didn't get a chance yet to check the IPC.. I need to act quickly and purchase the high time (running w/logs) engine I found. I will work it over real good this winter and maybe install in my plane (w/out weights).. not sure how much smoother the weighted engine is, mine is pretty darn smooth
the crankcases are the same. Good Luck, Mahlon
TParker
Well Known Member
Not sure if this is what you mean, but I wouldn't recommend removing the counterweights from a counterweighted crank.
sansoneservices
Well Known Member
I mean remove my engine w/o counterweights to install the engine WITH counterweights (after I overhaul)
I'm just not sure if I will notice any difference for the amount of labor.
Lycoming counterweights do not make you engine run smoother to your feel. They are pendulum type and there to counter forces on the crankshaft the engine produces naturally. The counterweighted and non counterweighted engines are physically the same as each other externally and internally the only difference between them is the counterweighs and the cheeks on the crankshaft to install them on. And yes you could remove the counterweights from the counterweighted shaft and use the shaft like that and just have a non counterweighted engine. That would be a waste of a good counterweighted shaft but would be doable. If you desire is to have a really smooth running engine bay balance each cylinders reciprocating parts and also combustion balance the volume of each cylinder to each other. Then after installation and break in, dynamic balance the prop and engine combination. If you do that you will have the smoothest running engine prop combination possible. Good Luck, Mahlon
sansoneservices
Well Known Member
Thanks mahlon, I was under the impression the counterweights reduce vibration the occupants feel. I'm considering a purchase of a used crankcase with cam and crank installed. I would rather have just the crankcase halves so Divco can restore to new specs. My current crank is not counterweighted so I was curious as to the benefit
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If you're going to do any aerobatics or formation flying, I would recommend the NON-Counterweighted crank.
Per my memory from Jim at Whirlwind: “ During each Lycoming 360 engine revolution there is 2 power pulses of + 2000 ftlb and -1500 ftlbs for a total of 3500 ftlb force torsionally. A counter weighted crank reduces these forces by 35% - 40 %. These forces are severe enough to fail a prop hub.”
Whirlwinds 330 hub is built to take the punishment of a non counterweighted crank but is aprox. 17 lbs heavier than the 300 series designed for counterweighted cranks. In my case I built a custom counterweighted engine for my 4 to save the 17 lbs off the nose.
PS The crankcases are identical.
Whirlwinds 330 hub is built to take the punishment of a non counterweighted crank but is aprox. 17 lbs heavier than the 300 series designed for counterweighted cranks. In my case I built a custom counterweighted engine for my 4 to save the 17 lbs off the nose.
PS The crankcases are identical.
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Why is a counterweighted crank not recommended?
sansoneservices
Well Known Member
The counterweighted crank is heavier and there's a service bulletin on proper selection of weights and bushings. I believe that's the only issue, very minor. My question was: does the weighted crank feel smoother to occupants.
Rapid throttle changes are discouraged with CW cranks.
sansoneservices
Well Known Member
Thanks for the info
BoydBirchler
Well Known Member
As far as I know Lycoming never made a AEIO 540 or 580 without counterweights. All of the Extra's, MX's, Edge 540's and S2 Pitts' have counter weighted cranks. A few of the 4 cylinder aerobatic planes also used counterweighted cranks. In my thousands of hours with and around aerobatic planes I never saw or heard a problem with the counter weights in an aerobatic plane.
That's interesting! I was taught the same thing as what Walt said above. Here is a service bulletin I dug up on the subject but it pertains to geared and rotorcraft engines. It lists these engines: GO-435, GO-480, IGO-480. GSO-480, IGSO-480. IGO-540, IGSO-540, VO-540. TIGO-541. Most of them are geared so that must multiply the forces on the affected engine parts while the non-geared engines do not have the force?? Perhaps the origins of an old wives tale?
Service Bulletin No. 245D
The CW's have bores with brass bushings, as do the ears on the crank. The pins that hold the weights in place are a good 1/8" or more smaller than the bores. The exact difference is part of the tuning I believe and why they have so many different pin sizes. Basically the weight floats a bit due to this and I think how it does its thing absorbing impulses. Therefore rapid acceleration or deceleration of the crank with the weights moving on inertia (not firmly attached to crank) will slam the pin into the bushings and wear them down over time. Brass bushings are fine for rotational loads, but don't do well with impact loads. I believe this is what Lyc means by de-tuning.
Thanks for clarifying. Its been too many years I guess, as I remember the bushings being bronze. The still wear though. The ones on the 540 i rebuilt had visible wear in two areas,
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