I have an O-235-C1, one of the earlier O-235 versions. The engine is low compression rated at 108 HP at 2600, though the engine is placarded at 2800 RPM.

I have a cross -over exhaust system,  light weight starter,  MA3A carb, bendix mags, dual electric fuel pumps (no engine driven pump), oil filter adapter and an electric primer system. The prop is a 3 blade ground adjustable Warp Drive HP prop.

I have 240 hours on an overhauled engine. I've had a few oil "seeps" to deal with but the engine has been solid so far. 

Normal cruise is about 90 knots at 2550 rpm. Fuel consumption is around 6.5 gph.

Dry weight is 804 lb. and the plane is polished aluminum, no paint. 

I get a level of comfort flying behind a Lycoming engine. NOT bashing other engines,  it's just a personal opinion. 

One downside is the weight.  The nose is heavy which is only relevant during the landing phase.  Full trim is not enough to relieve stick pressure with any flaps extended. However I have gotten used to it and for me it has become a non-issue.

One challenge in using an O-235 is the relatively few flying 601/650's flying with this engine. It can make the learning curve a little harder than some of the more popular engines.

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I have the L2C 0-235, mechanical fuel pump + electric back up. I don't have an oil filter or cooler. Oil temps so for in 90 degree+ temps are around 225. I have the three blade adjustable Warp Drive prop. MA3 carb, cross over exhaust. Mine has the Sparrow Hawk conversion, 125 hp. Other than that it is pretty much like Gary's. I have about 250 hours on fresh OH. It burns maybe a quart of oil every ten hours or so and I do have some oil seepage. I bought this plane complete, and I now have about 25 hours behind this engine. I only have a couple of 1 hour plus flight is cruise, 3000 MSL. I have used 2400 rpm to do my testing and I indicate about 120 MPH, and with little or no wind my ground speeds are between 120, sometimes 125 and 113 MPH. I'm burning around 7.5 GPH with out any leaning. My red line is 2800 RPM, but so for I haven't come close to that. My plane weighs 840 pounds. I was in the process of building an XL 601b when this plane came up for sale at a bargain price, so I bought it. The 601 I'm building also has the 0-235, the older C1B rated at 115 HP 2800 RPM. It only has 400 hrs SMOH and I bought the complete engine prop minus exhaust for six thousand. Considered other engines, some alternative engines, but they were all in the same price range or more. I won't knock other engines, but for my piece of mind I went for the Lycoming. I do most of my landings with out flaps, so I have plenty of elevator for landing, if anything I have to be careful not to let the nose come up before the nose wheel touches. A couple of drawbacks with the 125 hp engine, no auto fuel, 100 LL only and a 2000 vr the 2400 HR TBO.I'm almost 71, but I don't believe the TBO will be an issue with me. To sum it up I'm very happy and feel comfortable with my Lycoming extra weight and all. I still keep my eyes open for fuel consumption, the clock & that open field .. 

Thanks, Gary and Gil, for getting this forum going!  I'm sure many of the members will find your detailed posts useful as you're giving "real world" numbers and performance figures.  Also, since there are a seemingly unlimited number of places where parts, repairs, inspections, etc. can be obtained, I hope members will contribute references and recommendations.


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I am in the process of rebuilding a 601 XLB that suffered a nose gear collapse. It had an O-235 (not sure what version), and I plan on replacing it with another O-235. I just purchased a C2C variant and it has ~1450 hours since new. The cylinders were put on another plane by the previous owner. I am contemplating a complete overhaul with either refurbished or new cylinder assemblies. This way I know exactly what I'm flying behind. The weight of this motor has been considered, and I believe the reliable history Lycoming has provided over the years makes this the best choice for me. I looked at Corvair, Viking, Continentals, and a host of others. The original builder of my plane said it flew very well with the O-235. Plus, the plane is essentially setup to accept the motor with little modification (other than a complete new firewall and cabin floor). I have an air box, and a very simple straight exhaust. The cowling was damaged, and repairing it may add unwanted additional weight.

I am sure the weight of the motor contributed to the nose gear collapse. I don't have all the facts about the incident, but apparently after touch down of the main gear, one of the wheels developed a shimmy. The PIC pulled back lightly striking the tail and the nose of the plane came down hard. I don't know how much experience the pilot had with the plane.

My engine has a mechanical fuel pump, and I think I will add an eclectic back up pump as well. I like that idea. One thing I would like to know is where is a good place to get machine work done in the Midwest? I live in Iowa, and I haven't explored this topic as of yet. I have also reached out to my local EAA chapter in Cedar Rapids, but I am not sure how active they are.

Anyway, I don't claim to be an expert. I'm just looking for guidance during this journey. Sharing information that is learned from proven examples helps others in making critical decisions with their applications.



I don't know what happen to your plane, but I have the same engine on my plane. Once I landed scraping the eye bolt on the tail, no biggie. I try to always hold my nose wheel off as long as I can, but at times it hits harder that I would like. I've heard all this talk about how much heaver this engine is,, but check and you will find it is just a few pounds. My A&P even commented on how strongly built the nose gear on the 601 was built. I land most of the time with out flaps holding 80 MPH all around the pattern and on final. I have a 3000 foot strip at my home field and neve come close to running out of asphalt. With practice you can kiss the nose wheel with very little back pressure without flaps. I looked at other 601's out there with various engines, but being a very timid  old pilot I felt the 0-200 & 0-235 engines were tried and true for many many years and had the best TBO. Most of the Lycoming 0-235 also had a longer TBO & HP. That being said there are many good alternatives engine choices out there, it all come down to what you can afford nd what your comfortable with. To rebuild that engine wont be cheap. Did you have your  engine oil analyzed , check crankshaft for run out and a compression check? Have an A&P check out your engine, it really don't have all that many hours on a 2400 TBO

Unfortunately I didn't get the cylinder assemblies with the low time bottom end. The previous owner put them on another aircraft. I did get 4 cylinders with the engine, but they are 3,000 hours first run quality. I will have the case examined to determine run out. I was told it was fine, but having and A&P inspect them is worth while.



If your cylinders are off make sure you check camshaft for rust. You may want to pickle the engine. Did the engine have a prop strike? I maybe parting out the second XL 601 I was building. I have the cowl engine mount and a C1B with 400 hours & chrome cylinders. 

The engine had been pickled, so hopefully rust will not be an issue.

What are you asking for the cowl and engine mount?

not sure I want to sell yet, but I would discount them some, but not a lot as they have been installed on my project, but for all practical purposes still new. 

I just made my first 420 mile cross country enroute  to the Pietenpol convention and Oshkosh. I flew mostly at 3500 foot MSL and at 2400 RPM. I used 28 gallons of fuel that figured out to 7.1 GPH. I also use a little less than a quart of oil. My l tempt cruise was constant 225.My ias was 120 mph and my ground speed was close to that most of the trip. I have the 125 HP 0-235 and 75%power is 2400 rpm and the stated fuel burn is around 7 GPH. 

"One downside is the weight. The nose is heavy which is only relevant during the landing phase. Full trim is not enough to relieve stick pressure with any flaps extended. However I have gotten used to it and for me it has become a non-issue."

I would be VERY careful flying this airplane.  If your engine stopped, due to fuel starvation or any other issues, you would instantly loose the downforce created by the propwash over the tail.  

You would be forced to nose the airplane over drastically to build speed, then hope for enough altitude to make it all work in your favor. 

Even with plenty of altitude, you would have to land 10+ mph faster than normal.  This is significant if the terrain is unpleasant. 

And finally, if you bounced the first landing attempt, the airplane would not be able to maintain the speed needed to keep the nose up and you would likely hit nose first.

You might want to consider 15 lb securely fastened in the tail

I generally land without flaps, engine out I would probably do the same, but it would really depend on everything you would be dealing with. My battery is located in the tail and I think it is around 13 pounds. Most of my landings my rpm is about 500 , and tend to float. It is true with full flaps it takes most of your trim, but in mine it isn't horrible. All things considered I would buy another 0235, and I did for a second XL6010 Im building. Their history and TBO is something to consider. You are right about a heavy nose engine out if your cg is off, you won't be able to flair properly

hey Gil, or anyone.

  I'm researching engines to put in my 750 ,and I like the idea of the power a O-320 lycoming  will make. Wikipedia states that a O-235 weights 235 - 245 lbs depending on model, the O-240 continental  @ 246 lbs ,and the O-320 @ 244 lbs. All weights are suppose to be dry weights but only pulled from Wikipedia, so i'm not "sure " of accuracy.

- Anyone have an opinion of if these numbers seem right?

- What else could be a factor that may make the o-320 more heavy than the 235 and 240?

There isn't much info out there on the 320's that are flying but a little more on the other 2 model engines where most say that they are heavy but with proper planning of the rest of the air frame you can make a plane that is safe.



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