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CAM and Valve Springs Question

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Old 09-28-2023, 06:15 PM
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I've been told they are one of the greatest aircraft engines ever designed
I couldn't comment on that; but they SURE AS HELL are popular. They're in EVERYTHING. Cessna, Piper, you name it. I even recall one in a Hughes 300C (helicopter-shaped object, somewhat resembling a soap bubble with a rotor and a tail) that did some work for a radio & TV station group I was an engineer for years ago.
Old 09-28-2023, 06:47 PM
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Lycoming aircraft engines have been around forever, some injected (cruder than the early 50's Rochester setup) and most carbureted with a Marvel-Schebler carburetor from the early 20th century.
All use dual magnetos, but the failure rate is worse than any present-day electronic set-up.
If you get a reman, balancing is optional.
They're about as refined as any tractor engine from the mid 20th century. They don't run much over 2500 RPM, and you wouldn't want to as they'll shake apart much above that (see the balancing comment previous to this).
They can be brought into the present day with headers, electronic ignition and electronic fuel injection, but unless it's in an experimental plane, it's illegal to do so.
Old 09-28-2023, 07:15 PM
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I spent a lot of fun times behind an O-320 Lycoming in a 172K Cessna. And yeah, twin mags. One of the checks you did before taking off was to turn one mag off and then the other. If the RPM didn't change, you knew you were running on one mag. In that situation, you found the trouble before even thinking about taking off.

The valve springs on that engine looked the springs you'd use to check PTV and degree in the cam on an LS engine. I don't know what gauge the wire was, but it was closer to the spring on a screen door than even stock LS truck springs. Red line on that engine was 2700 rpm.

On one of the last flights I took in that Cessna involved severe pucker factor. A long trip at high altitude. You had to plan the decent to not shock cool the engine during the decent. I did everything by the book. When I got down to 1000' above ground level and added power, I found only three of my four cylinders were making power. Stuck valve. I limped it back to my farm airstrip. My passenger just about lost his mind. A more robust valve spring probably would have eliminated that. Apparently, that was pretty common on those engines. I found out after all of this fun and games that Marvel Mystery Oil would have helped. Never ran without it after that.
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Old 09-29-2023, 02:37 PM
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The last few posts regarding Lycoming (and the same can be said for Continental engines) raise some interesting points. The reasons many in the experimental world are moving to auto engine conversions are many. The first to go down this path was the old Covair engine that was an air-cooled engine like the Lycoming and Continental's. Lots of people have put V6's and V8's in experimental planes. One of the early issues was they didn't put any form of a gear box/transmission on the engine. Autoengines are not designed to take 500 lb continuous loads in-line with the crankshaft. As a result they blew the bearings and there were a number of unfortunate accidents. This lead to the invention of the Power System Reduction Unit (PSRU), what is commonly called a transmission in a car. They are also called gear-boxes in the airboat community and are essentially a 1 gear transmission with a 1.5-2.1 to 1 gear ratio. They convert the rotary motion at 3,500-5,000 RPM to 2,000-2,700 RPM of the prop and incorporate a set of bearings to handle the load parallel with the engine crankshaft. Some individuals have converted production aircraft to experimental with autoengines/PSRU's.

Unfortunately, the revenue stream for a certificated aircraft engine is no where near as large as the automobile market. As a result there isn't the investment for technology advancement that we saw with the LS1 and the subsequent LS family. The other motivation for use of an autoengine is cost. A 300 HP Lycoming IO-540 runs $120k+ new and $70k+ rebuilt. A typical IO-540 must go thru a overhaul process every 1500-1800 hours of run-time. In an autoengine that might be the equivalent of every 75,000-90,000 miles if your driving 50-60 mph all the time. The cost of an overhaul on an IO-540 is $30-$40k. For these reasons groups are popping up that do autoengine conversions for a fee in the experimental world. I know of two in the LS family and another there are others focused on the 80-150 HP range. The MooseMods facebook page has a short video clip of their production are with 7 planes undergoing stock LS3 installations with a 400-525 HP engines.

https://autopsrus.com/
http://www.moosemods.com/
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Old 09-29-2023, 06:26 PM
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The original Continental Motor Co. is long gone. IIRC, Teledyne bought the rights to produce/manufacture them in the late 1960s. Like many of the Detroit area manufacturers, the foundry building was razed many years ago. The water tower and smokestack were all that remained. Until somehow scrappers managed to dismantle the water tower some years back. All that remains of the once popular company is the brick chimney, with white letters spelling Continental. You can see it still standing behind a dollar store. The 1,000,000+ square foot Packard plant will be next....
Old 09-29-2023, 06:52 PM
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I think Teledyne sold the Continental aircraft engine business to the Chinese a few years back. They still make some four- and six-cylinder aircraft engines.
Old 09-29-2023, 07:46 PM
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There was an old Continental engine that got put into some kind of armored vehicles like those giant trucks you only see nowadays in like Band of Brothers or Saving Private Ryan, that got sold on the surplus market back in the 70s as heavy-duty construction site hardware. Rumor has it, they would run on ANYTHING. Gasoline, diesel, alcohol (whisky), ... ANYTHING. I've even heard stories that a unit equipped with those needed fuel while driving through France in the late 40s and came across a perfume factory, and used MANY MANY barrels of that as fuel. They quit when they realized the enema could smell them coming. Seems like that particular engine had coolant passages through the crank and rods and up into the pistons, hence its "multi-fuel" capabilities: it was all but immortal, short of direct atomic blast. Not much HP, not many RPMs, butt it would KEEP GOING. Anybody ever work on one of those?
Old 10-01-2023, 04:41 PM
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Yes, Continental and Lycoming have seen lots of changes in direction and ownership thru the years. Thanks for all the feedback here!



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