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Early o-320 engine mount help

andyg

Active Member
I have what's tagged as a 1957 O-320 (no dash but same as an A1A) that has flat engine mounts. Completely flat on the firewall side and a slight round recess on the front side. There is no conical shape to the mounts on this engine at all.

What do I really have here? What kind of mounts work on these style engines?

Thanks
Andy
 
The 4 rear mounting eye tabs have large double tapered holes? Conical shaped bushings go in these holes, 4 facing forward & 4 facing backwards. Therefore called 'Conical Mounts'.
 
Ralph,
My information say there was a 0320 D2G
160 HP 91/96 octane. Compression 8:5:1
7/16 inch flange prop bolts with Slick Mags.

I am not smart, when you need information about any Lycoming engine,
try: Ask.com
then type in 0320 Lycoming and look for Wikipedia and it will tell you all the engines and there specifications.
Dave

fly high!
 
D2G should have Dynafocal mounts, the aft surface of the mount tabs should be angled.

My thoughts are that maybe this engine might be some sort of ground propulsion unit, like the O290-G. Some modification to the case mounting tabs had to be performed to be used on regular style aircraft engine mounts, although some homebuilts were built with the 'G' type mounts.

O-290-Gs used to be popular in homebuilding back when they were plentiful & cheap in the 60's & 70's. Also I seem to remember that 290 cases could be upgraded to 320 cylinders with the dual plugs & changed out accessory cases, etc.

'G' engines aren't even mentioned in Van's listing in section 11
 
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Unknown engine mount.

I wondered if it was some kind of ground unit. Maybe an O-290G with 320 stuff on it. Has dual slick mags. I’ll look for a surgical procedure the next time I’m there.

Update: So the bottom looks like conical mounts but the top is flat metal. Hmmm
 
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Have similar

I have a O320 also with no letter before the serial number. I was told by Lycoming it is one of the first production models. It is a narrow deck, conical mount. I will take a pictire if you want.
 
Van's offers or used to offer an engine mount for conical mount engines. If you are tearing down the engine for rebuild, most shops doing your case work will change the mounts to dynafocal for about $250, if that's what you want/need.

Larry
 
O-290G engine cases are like a conical mount, but only have bolt holes bored through, not the conical shapes milled into the mount ears for the rubber cone mounts cushions. Yours may have only the front half modified or simply worn?
O-290 cases are very similar to O-320 E2D and the O-235. That is to say it has 2 separate front main bearings, similar to the other main bearings, and can never be upgraded to run a constant speed propeller. Other O-320s and O-360s have a long single piece front main bearing and more supporting material around this bearing in the case. The right side of these cases have a boss for drilling an oil port. On constant speed propeller equipped engines, this is drilled and has a fitting and hose/pipe from the propeller governor. These long main bearing cased O-320 engines are eligible for Lycoming's upgrade to 160 HP via replacing 7:1 pistons with 8.5:1 pistons. Many home builders have upgraded the 'lesser' main bearing 150 HP O-320 to 8.5:1 pistons without ill effect.
I have an O-290G powered T-18 with O-320 crank, rods, sump, carb, accessory case etc. The O-320 crankshaft has the same stroke as an O-290, but it has a stronger propeller flange (see below). O-290 cylinders, pistons and rings are getting hard to find & expensive, new after market pistons & rings are now relieving that. I'm going the upgrade route for fun. I also have an O-290G case with 'conical' mod so poorly done I consider the case nearly unusable.
I just got a new 'old stock' O-290G case to make into an O-320 by boring the cylinder spigots in the case to accept O-320 cylinders and gain 30 cubic inches. This is an old Airboat mod. the case will fit my T-18 airframe's existing mount. O-290G engines have a solid tappet cam, and the case has special oil troughs next to the tappet bosses that catch oil flung off the crankshaft, then pass that oil thru drilled passages to the push rod tubes where the oil drools down the faces of the heads and carries off heat. Cool old retro-tech. I think O-235s and O-290D aero engines are similar in this but have regular conical mounts.
It's a fun project I use to stay in touch with my several friends in the T-18 group.
You could possibly identify the case as being from an O-290G by looking at the case nose right behind the propeller. O-290G units were attached to generators, so they had a large flange with a ring of bolt holes to mount the generator. Also the crankshaft has a thin flange and did not have the propeller mount bushings. Engines converted to flight use must have the big flange cut off, and you can often see the cut marks, which will look hand filed, maybe hexagonal instead of round cast. Also the thin prop flange may have a pair of half moon re-enforcing doubler plates behind the flange.
Also, O-290 is a 'Narrow Deck' engine. The cylinder flange and bolt pattern is different than later 'Wide Deck' engines. O-290 cylinders (4-7/8" bore cylinders) are held down with regular hex head nuts. When Lycoming increased the bore to 5-1/8" (O-320 & O-360), the margins around the case studs became narrower, so they used barrel shaped nuts with an internal drive (think Allen head) to reduce the nut diameter. You should check, you may be looking at an O-290G. In that case, it's worth nothing because it's being sold by someone who does not know what it is or is mis-representing it. O-290, and O-290G are good engines, but aircraft sales are based on knowledge and trust.
Mine has a sump from an O-320, and the data tag is on the sump, so it has the data tag from the engine it was manufactured with. Misleading unless you read the logbook.
My RV-8 has a narrow deck conical mount O-360 that began life as an IVO-360A1A in a Brantley helicopter. Van's did not stock the motor mount, but when you order it, they have a subcontractor make it in about 2 weeks. In my case, the builder was near, so he called me and I picked it up in person and had a tour of his shop.
Awesome people in aviation!
 
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Many Thanks

Shipchief - That's why I love this group! I will check all those items you've listed and give the outcome.

I do know it has the internal drive head bolts and not the normal 6 pt hex head.

I will update in the next few days.
 
lr172 -
How do they fill the straight hole when they make the mount a Dynafocal?

I assume they fill the straight hole and the machine the angled pad and drill the angled hole.

Andy
 
So I found info online that says the O-290G had a crank flange thickness of .187 or 3/16? and the O-290D had a crank flange thickness of .250 or 1/4?.

What is the flange thickness of the O-320 and 0-360?

Andy
 
Engine numbers

The G in ground power units (O 290G) is a totally different designation than the G in other Lycoming engines.
 
Crank

Doesn't exactly answer your question. The 0 320 and O 360 cranks come in lightening hole(early) and non lightening hole configurations. There are aerobatic cranks for both engines and they are thicker flange. I believe the early 0 320 flanges were thinner than current production non aerobatic flanges. but I don't have a flange dimension.
 
Mopunt

lr172 -
How do they fill the straight hole when they make the mount a Dynafocal?

I assume they fill the straight hole and the machine the angled pad and drill the angled hole.

Andy
The crankcase shops weld up the existing holes, machine the angle and drill the angled holes. This is a lot of work and at the most recent price I have of $300 quite a bargain.
The basic castings are all the same from 0 235 to 0 360 for the engine mount "ears". Conical or type I( dynafocal engines will all fit the asame respective engine mount, ie the cases are all the same dimensions between the mount"ears".
 
Photo links

Here is a link to photobucket. Look at 2013 Petit Jean folder. There’s a few unrelated pictures in there but lots of pictures of this engine.

2013%20Petit%20Jean%20RV%20FLY-IN


So from what I can tell, it has the boss and is tapped for CS prop, flat mounts on the case, and no evidence of a big gen mounting flange removal. I’m stumped. Oh and the case has L116-47 stamped into the flat boss on top towaed the rear.

http://s296.photobucket.com/user/andyg1932/library/2013 Petit Jean RV FLY-IN
 
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Here’s the answer.

Anyone ever heard of an O-320-G4? So that’s what I have. Here is the partial answer. It’s a lycoming O-320-G4. A non-certified engine almost exactly like the certified version except for engine mounts. I has primer holes tapped and plugged. It has heavy (nomal certified as opposed to light ground unit) prop flange, and boss that is tapped for cs prop. May, 1961. And no ground unit front flange to cut off. According to Lycoming, this was an identical engine to the certified engine except not certified. It was the equivalent of the xo-320 today for the experimental market that was growing back then. He couldn’t explain the flat engine mounts instead of conical mounts.
 
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So the bottom mounts are conical but the top are flat.

Does this mean the top have been welded up and holes redrilled or something else?
 
I looked at your pictures. That is interesting. You can machine out the mount ears to take the conical mount, and it would work. To my eye, the bottom mounts are not conical, they just have squished out rubber washers. There is a third mount under the output end of the engine.
However, that engine looks rather old and dirty. I wonder if it was pushing an airboat before you got it? That's a rough life. You might want to take it apart, or take it partially apart and inspect for rust, cam damage, cylinder overheating, presence of an oil inlet screen in the sump etc.
Does it have a Log Book? If not, start one.
The magnetos and harnesses look pretty old. ten years is the life limit of the grease inside, even if they haven't been run. (Slick service rep "Joe" told me that @ the Reno air races while we waited in line for some food. Small world eh?)
The MA-4 Carb is right, but there have been Airworthiness Directives that you should know about (One piece venturii, Floats, maybe others)
The oil pump has an AD for steel gears (once upon a time they had aluminum gears, then sintered gears? I think the oil pump body has been superseded as well) The rear case is not difficult to remove, and then you can check some other things that will increase your future confidence, like the crankshaft gear, which must be inspected if there has ever been a prop strike, and the wear /corrosion of the idler gears and shafts. You also want to know if this engine can drive a fuel pump, so you will be looking for the eccentric on the left idler gear, and the fuel pump pushrod. You may want the tachometer drive and vacuum pump drive to work, so inspect those gears.
Take a valve cover off and see if you have adjustable rockers. if not, you have a hydraulic cam. Now pull the spark plugs and look inside the cylinders.
The sump is a collecting point for sediment, and should be removed and cleaned. It will have sediment, mostly carbon, so don't be alarmed. But it shouldn't have a lot of metal. Too bad you can't see much of the inside of the engine, there is only a small slit of an opening under the back cylinders.
You have to remove a cylinder if you want to look at cam lobes. Worn lobes and pitted lifters are the bane of these engines, especially old engines that rusted inside.
I'm just getting started....
I've been told that if someone offers you an old Aerocommander Twin for free; RUN AWAY!
Yea, kinda like that. Just consider what I said and ask some other home builders.
 
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