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Old 11-22-2015, 08:42 PM   #101
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Yep. Remember now...... hydrolock in the bottom cylinders. You are all correct. And, come to think of it.... same reason I had to pull the gas pedal BACK with my hand (which acted as a valve lifter) for 30 seconds before letting go and starting a ....... Leopard I tank with a 27L 10 CYL multi fuel engine.

Ah, If I could only remember all I've forgotten.
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Old 11-22-2015, 08:53 PM   #102
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If you are really concerned about dry bearings on startup you can plumb in a spring loaded resevoir and electric selinoid valve. The selinoid closes when you shut off the engine. when you turn on the key switch the selinoid opens and releases the oil from the canister lubricating the bearings. I consider it a waste of time and $$$. But then I dont have a problem letting a diesel engine sit for years with old oil, fuel, and heaven forbid antifreez and then starting it up and putting it to work. May even get around to changing the oil, but probably not this year. Never had a problem and I have more important things to worry about.
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Old 11-22-2015, 09:44 PM   #103
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If you are really concerned about dry bearings on startup you can plumb in a spring loaded resevoir and electric selinoid valve. The selinoid closes when you shut off the engine. when you turn on the key switch the selinoid opens and releases the oil from the canister lubricating the bearings. I consider it a waste of time and $$$. But then I dont have a problem letting a diesel engine sit for years with old oil, fuel, and heaven forbid antifreez and then starting it up and putting it to work. May even get around to changing the oil, but probably not this year. Never had a problem and I have more important things to worry about.
There ya go bud. Don't let a selinoid get in your way. Or a solenoid for that matter.

While I'm making fun of you I have to admit that I put 160,000 (!!!!!) miles on my college car and never got an oil change, and it ran like a bat out of hell, probably thanks to me flooring it at all times. Now I DID have more important things to worry about, of the coed flavor.

Still, if it was my $XX0,000 boat, I would think twice.
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Old 11-22-2015, 10:57 PM   #104
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Yes I am an aviator, but radial engines were WAY before my time. I do remember though, that the engineer would "count the blades" as in so many rotations before the mags (ignition) were turned on. This WAS to get the oil flowing.
No it isn't. It's to distribute fuel through the manifold and into the cylinders to ensure a smooth start when the mags are switched on. It's part of the technique used to minimize the risk of a backfire on startup. I do the same thing with the Pratt & Whitney R-985 on the planes I fly and it's got nothing to do with oil distribution.
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Old 11-23-2015, 06:52 AM   #105
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My understanding of the reason for 2 full revolutions before fuel and ignition is the lowest cylinders can fill with engine oil (oil tanks are frequently above the lower cylinders in the wing) which would hydraulicaly lock the engine.

The starter is weak so will not usually do damage if the engine is full of oil.

With R3350 there was a hookup to pre oil the engine , by a hand pump.

And in cold weather operations the oil was diluted with gasoline to thin it for a cold start.

There was a NATOPS table of expected low temps , oil quantity reading and how many seconds the dilute switch needed to be held while the warm engine was ideling.before shutdown.

On start there was also a table for how many min. the CHT had to be above a certain temp , to evaporate the AV gas in order to go fly.

A half hour or more of extra fun for the crew.
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Old 11-23-2015, 01:13 PM   #106
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And in cold weather operations the oil was diluted with gasoline to thin it for a cold start.

There was a NATOPS table of expected low temps , oil quantity reading and how many seconds the dilute switch needed to be held while the warm engine was ideling.before shutdown.

.
The R985 has the same system but we've never had to use it in our climate.
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Old 11-23-2015, 01:25 PM   #107
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Lots of things I cant spell. Very few things about a diesel engine that I dont know. Can you say that,,,ozker.
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Old 11-24-2015, 06:30 AM   #108
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No it isn't. It's to distribute fuel through the manifold and into the cylinders to ensure a smooth start when the mags are switched on. It's part of the technique used to minimize the risk of a backfire on startup. I do the same thing with the Pratt & Whitney R-985 on the planes I fly and it's got nothing to do with oil distribution.
yup. And it's that "lack" of technique that was used to initiate greenhorns to the flight deck. There is nothing more scary than having one of those monsters backfire on you as you stand under one feebly holding up a fire extinguisher. Explosion, fire, smoke, pee. Everytime.
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Old 11-24-2015, 12:19 PM   #109
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. There is nothing more scary than having one of those monsters backfire on you as you stand under one feebly holding up a fire extinguisher. Explosion, fire, smoke, pee. Everytime.
In addition to the scary part a backfire can also be very hard on the engine. Kenmore Air Harbor's engine overhaul mechanic once showed me the damage than can occur to a supercharger from the shock load of a backfire. Once he explained that I was even more cautious to avoid a backfire.
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Old 11-24-2015, 03:06 PM   #110
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No it isn't. It's to distribute fuel through the manifold and into the cylinders to ensure a smooth start when the mags are switched on. It's part of the technique used to minimize the risk of a backfire on startup. I do the same thing with the Pratt & Whitney R-985 on the planes I fly and it's got nothing to do with oil distribution.
Sit corrected once again. Thank you. Disclaimer, don't play with radials, just RB-211's....
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Old 11-24-2015, 07:37 PM   #111
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Well, all you guys trump me, i know nothing about radial engines. But always admired them.
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Old 11-24-2015, 07:51 PM   #112
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Well, all you guys trump me, i know nothing about radial engines. But always admired them.
It's a remarkable (to me) design. For ages I didn't understand how they could work until I started flying a plane that has one and learned about the master rod and how the other connecting rods are all connected to it and not to the crank itself.

One of the most complex pieces of machinery I've ever seen is the Pratt & Whitney R-4360 (so named for the total cubic inch displacement of the engine). It has four radial rows of seven cylinders each. So twenty-eight cylinders, fifty six spark plugs. It started out as a 3,000 hp engine but this was eventually upped to 3,500 hp. The rows were staggered so to maximize the airflow around the cylinders.

It powered planes like the Goodyear F2G Corsair, Boeing B-50 Superfortress, the Boeing 377 Stratoliner, the Convair B-36, the C-117 Flying Boxcar, and the Hughes H4 Hercules (aka Spruce Goose). A couple of these in our GB36 would be pretty cool.

Another intriguing albeit inefficient engine is the rotary. It's use died out pretty quick after WWI but this was the one where the crank was bolted to the airframe and the cylinders and the attached propeller revolved around the crank. It made for a plane that had an amazing roll rate if the pilot wanted to turn in the opposite direction of the engine's rotation.
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Old 11-24-2015, 08:08 PM   #113
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It's one more reason merging a fall layup and haul-out yields some nice congruence. The yard is not busy, if you need them or their hands. If you find 5 frozen seacocks as I just did, you don't float through the winter with 5 legs on pinochle. They quickly get serviced during the haul-out, which they require. Same with waiting six more months to change those overdue shaft and engine zincs...A nice time to refresh your cooling system too, as in anti-freeze.

After setting up an oil bath heater in your down low, you should be safe and warm, and come springtime - you're turnkey - and out of the engine room and topsides for the key ego stuff.
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