A

Andrew Maschmedt

Member
I don't think it exists but does anyone know of an O-320 with angle valves? If you can get 180 HP with O-360 parallel valve and 200 HP with an angle valve engine of the same capacity, could you get 178 HP from an O-320? It's something that's been in the back of my mind now that I am close to needing an engine for my 6a.
Be gentle with me as it is my first time on the forums.
 
You'll probably be better off with a parallel valve O-360 in terms of both weight and width, even if you could get the angle-valve barrels made up.

I don't know for sure, but I think most of the weight difference between the O-320 and O-360 is in the longer stroke crankshaft and the longer cylinder barrels. The angle valve head must be a fair bit taller/wider/heavier than a parallel valve one, since it adds nearly an inch in width and 30lb in weight, not all of which weight might be in the head itself.

Perhaps you might consider ECi's O-340 which gives you the same width and presumably (nearly) weight as the O-320, but closer to 180hp (claimed).

A
 
I know of a 4 that had a Lycon built angle valve 320 in it. Used cylinders from a Lyc GO-480. It was one runnin engine. Don
 
I certainly think its ok to do, but economics are a consideration. Angle valve cylinders run about $1800/ea new, and you could probably get close to the same hp with high compression pistons and ECI cylinders, at half the cost. If you go for used/OHed angle valve cylinders, they are going for roughly the same as a new parallel valve cylinder.
 
Angle valves on a 6 ?

As I recall,to mount an angle valve in an RV6 modifications have to be made FWF. An RV 7 and 8 have been specifically designed for that engine. A parallel valve with a few H.P. upgrades will make you very happy.

Steve Barnes The builders Coach
 
I know what too much about this.... because I dream of building custom weird Lycs all the time.

O-290 and O-435 share the same displacement, -435 were Angle Valve (some at least)
O-320 and O-480 share the same displacement, -480 were angle valve (some at least)
O-360 and O-540 share the same displacement

As long as the narrow deck/wide deck bases are considered, any same displacement cylinder should swap with any other. Angle valve heads only start to shine up higher in the RPM band, and lean of peak, so if you run 2300 RPM rich of peak all the time, don't bother.

Finding 435 and 480 cylinders is a PITA.

O-290's and O-320s share the same stroke, therefore the cranks are interchangeable to some degree or another. I'm working on figuring out what dash number -320 crank will fit in an O-290-G. Also some people have machined out the -290 G case to fit up -320 cylinders (larger bore)

It would be interesting to see if a O-340 crank (longer stroke) would clear the case of a O-290-G with the angle valve 435 cylinder and low compression 125 HP pistons, torque baby.

320 and 360 share the same bore, with the 360 having and even longer stroke than the 340.
 
And interestingly enough, I just went on to factorycylinders.com and it looks like Lyc still makes cylinder kits for the 435 and 480. Between 1800 and 2400 depending on the kit. Cool beans. This would be an excellent resource for people that want new cylinders for their 290, since the parallel valve 290 head isn't made anymore.
 
osxuser said:
And interestingly enough, I just went on to factorycylinders.com and it looks like Lyc still makes cylinder kits for the 435 and 480. Between 1800 and 2400 depending on the kit. Cool beans. This would be an excellent resource for people that want new cylinders for their 290, since the parallel valve 290 head isn't made anymore.
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But what other parts do you need with these cylinders? Pistons, push rods, etc?

BTW, all of my pistons are .010 over, so I would need to buy new pistons as well. The other question is, can the O-290 case hold up to the extra power?
 
I saw an angle valve IO-320 on a Lancair 320. I heard the original owner took the wings off and stored the plane for a while. Another person bought the plane and it was being put back together when I saw it.

That's all I know about it.

Karl
 
N941WR said:
But what other parts do you need with these cylinders? Pistons, push rods, etc?

BTW, all of my pistons are .010 over, so I would need to buy new pistons as well. The other question is, can the O-290 case hold up to the extra power?
Click to expand...

Well, the cylinder kit's Lycoming sells is the complete top end, including piston, rings, valves, etc. The O-290 D2 case is pretty darn strong, so it should be no problem. The weak 290 is the O-290-G which is what I might be working with for my RV-4. Obviously you'd have to redo your baffles and stuff, and pick the cylinder piston combo that gives you the desired compression ratio too. They have high and low compression setups, I'll know more if I can get my hands on the parts manuals for the different engines, I'll have to see what I have at the hanger.

I do believe that the O-290-D2 that you have has the same crankshaft as some of the 150HP O-320s, so parts are available for that as well. The -290 isn't as much of an orphan as most people think.
 
Which ones do you need?

osxuser said:
Well, the cylinder kit's Lycoming sells is the complete top end, including piston, rings, valves, etc. The O-290 D2 case is pretty darn strong, so it should be no problem. The weak 290 is the O-290-G which is what I might be working with for my RV-4. Obviously you'd have to redo your baffles and stuff, and pick the cylinder piston combo that gives you the desired compression ratio too. They have high and low compression setups, I'll know more if I can get my hands on the parts manuals for the different engines, I'll have to see what I have at the hanger.

I do believe that the O-290-D2 that you have has the same crankshaft as some of the 150HP O-320s, so parts are available for that as well. The -290 isn't as much of an orphan as most people think.
Click to expand...

I have lots of the repair and parts manuals in PDF files. Tell me which ones you need and I will e-mail them to you.
 
osxuser said:
...I do believe that the O-290-D2 that you have has the same crankshaft as some of the 150HP O-320s, so parts are available for that as well. The -290 isn't as much of an orphan as most people think.
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Thanks for the info.

You are right about the O-290 not being much of an orphan. I have found about 40% of the parts are used in the O-235, 40% used in the O-320, and 20% unique to the O-290.

FYI, ECI makes .010 over rings for the O-290.

All O-290-D, D2, D2B, & D2C share the same crankshaft assembly and it is part number 62531. My parts manual does not list the G engine so I have no idea what that will be.

If you do build up an O-290 derivative for your RV, I suggest you buy Van's baffle kit and modify it, as I did. (Details are on my web site.) Also, the O-290 carb is hard to find but in my research, way back when, I found the Continental O-300 carb will work just fine. And to hear some "old timers" tell it, it will work better and these carbs are more readily available. These are both MA3 carb bodies, thus the sump has a smaller hole and bolt pattern than the MA4 carb used on the O-320.

I suspect that you will be right on the upper limit for the MA3 carb and the lower limit for the MA4 carb. Someone here might be able to comment further on that.
 
It's really weird, but I've got a bit of experience with the 290 already. The 290G was designed for a GPU and used in Vietnam by the military. When the conflict was over (for us anyway) a ton of these went on the surplus market and homebuilders snapped them up for conversions. The G used a unique crankshaft with a very thin flange because there was no thrust loading on it for the GPU application.

Modified with a backup flange, you can run them with a metal prop... but I prefer the thicker -290D or 320 crank. Cases haven't seemed to be a problem up through 150+ hp even on the G case.

The Whitman tailwind with the G I've worked on is using a MA-4spa carb, but at the 125HP rating, it's gets pretty rich, we limited the mixture travel, which seemed to help.

MA3spa is the ticket, the right sump setup. I'm planning a little somethin different, that I don't want to talk about too much until I get a lot more wrinkles worked out.

I just got my -320 crank to test fit with. GTG ;)
 
One other thought, the airboat guys can mill your O-290 case for the O-320 crank. Just don't tell them it is going on an airplane.
 
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