Military surplus in the crate teledyne 84 CI available new 400 bucks

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Aerowerx

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I know absolutely nothing about this motor. just stumbled across it. figured may be someone here interested - price seems right
https://fresno.craigslist.org/avo/d/fresno-military-surplus-airplane-engine/6987204944.html
Teledyne Continental 4A084. Should be able to do 40-45 HP if you take off all the unneeded stuff.

Nice reliable engine, but a bit heavy compared to others of the same HP. about 120 lb, IIRC. Some users have converted them to fuel injection, and get a bit more HP. Popular with air boat fans.

Low compression. Easy to prop start, which saves weight (no starter or alternator or battery).

Has a little brother, the 4A032, and a little sister, the 2A042.
 

challenger_II

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Fisher County, Tx. USA
4AO-84: Factory rating is 35hp at 3600rpm. When propped with a wood 54x26 propeller, turns 3150rpm +/-. According to the propeller load, makes slightly less power than a Rotax 377. Depending on the Dash number (Dash I-IV), can weigh anywhere between 125#, and 140#, stripped of everything not needed to fly with, plus propeller flange, and 4 qts oil.
Not going to win any power to weight contests, but is very reliable, cheap to operate, and maintain. Using a larger carb than original is counter-productive. Best carb I have found is the unit from the Kohler KT-17 twin.
 

akwrencher

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There are some threads on the ETLB forum about these engines. Some have fitted them with psru's.
 

Aerowerx

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There are some threads on the ETLB forum about these engines. Some have fitted them with psru's.
Why? No need for a PSRU. They run at the proper RPM for a prop.

From what I have read about them, they were originally designed towards the end of WW2 as a drone engine, so they ARE already essentially an aircraft engine. But they weren't used much for that because WW2 ended.

Then after WW2 they were used in Korea and Viet Nam as a ground power unit, with a governor to regulate the speed, and a cooling fan. When the military went to all diesel power in the late 1900s, they were all dumped on the surplus market.
 

crusty old aviator

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Feb 17, 2014
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Grantham, NH
There was a Yahoo Group devoted to this engine, run by a gal in the SW desert. Yahoo made some changes and the moderator decided she'd had enough, so the whole thing went fffft! A lot of good information went ffffft with it. They look like a small A-65, because they basically are, and there are several ultralight Cubs, Pups, Kittens, etc. flying with them. Their induction systems have long, non-symetrical runs of 1-1/4" aluminum tube between carb and valves, so some have installed SDS fuel injection systems, along with jet ski throttle bodies, with great success. The stock Slick magneto is the best ignition source, and there's no room in the head for a second plug. The heads won't handle super or turbocharging, they just don't have enough fin area. I never heard of one being dyno'd after being converted for flight, but most operators were pretty confident, based on prop sizes and in-flight rpm's, that they were getting 40 to 45 hp at 3600 rpm. Ron Ohler, in Michigan, makes prop hubs for them. $400 is a reasonable price for them, and many of the surplus ones, still in the olive drab gen-set, have never been run, or were overhauled and then placed in storage, so are 0 SMOH.
 

challenger_II

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Direct-drive, with a 54x26 Tennessee prop, the 5, or 6, engines I have set up turn 3150-3200 rpm. With the stock genny carb, they get erratic (lean-out, unreliably) because the original 1 1/16" venturi doesn't have enough velocity to pull fuel from the bowl. At the stated rpm, and with the stated propeller, this falls between a Rotax 377, and 277, with a 2:1 reduction drive. So, I would be skeptical of the quotes of 40-45hp.
Now, Les Smoot's modified engine, with EFI and electronic ignition, did gain substantial performance, but at the cost of weight, and complexity. Still, and all, his mod was very successful!

From my bench tests, substituting the mag with electronic ignition gained me 200rpm, with the same prop as mentioned above. With the Slick mag, and sub'ing the Kohler KT-17 carb (smaller venturi, and adjustable mixture), I gained 150rpm. So, the engine's do have promise, for the right airframe, and GW.

The machines I have personally flown with an AO-84 are: Quad City Challenger II (known airframe, to test an unknown engine, and NO: it wasn't going to carry two people with that engine!), TEAM Mini Max, empty weight of 368#, with the AO-84, and a Fisher FP-101. The Fisher was a bit iffy, but did fly. The Mini Max flew for several hundred hours, before the owner Went West. All this at a field elevation of 2100ft, in West Central Texas, hot, or cold. As to cold... you CERTAINLY want to fit carb heat! :)

As for the "asymmetrical" manifold tubes, the induction system is tuned. Each tube is the same length. The tube diameter is 1 3/8". And, #1 cylinder always seems to run a bit richer than the others.

When you find an original engine, it will have either a Fairbanks-Morse, or Slick mag. Both weigh the same, so if you're has a Fairbanks, and it works, don't change it out, thinking you can save weight.
 

Aerowerx

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Direct-drive, with a 54x26 Tennessee prop, the 5, or 6, engines I have set up turn 3150-3200 rpm. With the stock genny carb, they get erratic (lean-out, unreliably) because the original 1 1/16" venturi doesn't have enough velocity to pull fuel from the bowl. At the stated rpm, and with the stated propeller, this falls between a Rotax 377, and 277, with a 2:1 reduction drive. So, I would be skeptical of the quotes of 40-45hp......
Keep in mind that the stock carb, throttle, and choke was designed to run at a constant speed for generator use. Some comments I have read involve changing the carb and choke to get better performance with throttling.
 

Jerry Lytle

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Newport, Oregon
Carb ice has little to nothing to do with OAT. the worst case I had with carb ice the oat was around 65 F. and the Cessna 150 wouldn't even taxi without carb heat. It was a rental and the check pilot said this was common at Eureka CA.
 

challenger_II

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Keep in mind that the stock carb, throttle, and choke was designed to run at a constant speed for generator use. Some comments I have read involve changing the carb and choke to get better performance with throttling.
Also, the stock carb is designed for 3600rpm. Since we were propping the engine such that the max rpm, static, was 3150rpm, the stock carb did not meter fuel the best, especially at the higher throttle settings. Hence, going to a smaller venturi.
 

challenger_II

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Fisher County, Tx. USA
Carb ice has little to nothing to do with OAT. the worst case I had with carb ice the oat was around 65 F. and the Cessna 150 wouldn't even taxi without carb heat. It was a rental and the check pilot said this was common at Eureka CA.

Point taken. However, my intention was to note that carb heat is a "must-have" for this engine. Even the genny application had a warm-air system for the induction system.
 
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