What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

O320-E2A converted to C/S = Problems?

Saville

Saville

Well Known Member
Hi all!

I'm looking at an RV-4 (to buy) which sports an O-320 E2A. The owner says the engine was converted, by a previous owner, to a Constant Speed prop engine by, he believes, replacing the crank with a "hollow crank".

Also the 7:1 compression ratio was boosted to 8.5 via higher compression pistons.

Does anyone know of serious problems that occur when one converts an E2A in this way?

thanks!
 
O-320-E2A at 160HP and those pistons is really an O-320-D2A. The regular O-320-E2A crankshaft and front bearing setup is constant speed capable. So all he really did was add a prop gov drive, CS prop mounting dowels and CS prop plumbing to a O-320-D2A. Which is not going to present any problem as far as the engine or its operation is concerned.
Merry Christmas,
Mahlon
 
mahlon_r said:
O-320-E2A at 160HP and those pistons is really an O-320-D2A. The regular O-320-E2A crankshaft and front bearing setup is constant speed capable. So all he really did was add a prop gov drive, CS prop mounting dowels and CS prop plumbing to a O-320-D2A. Which is not going to present any problem as far as the engine or its operation is concerned.
Merry Christmas,
Mahlon
Click to expand...

Is it correct to say then, that an E2A is the same as a D2a except the pistons?

Thank you Mahlon and Merry Christmas to you.
 
I flew a converted -E2A with a Hartzell CS prop for 13-14 yrs with zero problems. Had higher compression (160-hp) pistons and pins too.
 
mahlon_r said:
The regular O-320-E2A crankshaft and front bearing setup is constant speed capable.
Mahlon
Click to expand...

So how does one figure out which O-320's are hollow cranked and have the bearing setup for C/S and which cannot be converted?

thanks
 
Engines

320E2D, E3G, E2H, E3D and E3H were originally configured for 0 235 front main bearing. E2H and E3H are not listed for any production aircraft.
 
jrs14855 said:
320E2D, E3G, E2H, E3D and E3H were originally configured for 0 235 front main bearing. E2H and E3H are not listed for any production aircraft.
Click to expand...


Is there a document somwhere that lists all the Lycoming engines and the bearings they have and the cranks they have?

thanks
 
Bearings

I cross referenced the parts book for the 0 235 bearings. This is only and E series issue and only the ones I listed have the 0 235 bearings. It is easy to pick out in the parts book because the 0 235 nose bearing is four piece vs two piece on all others.
 
jrs14855 said:
I cross referenced the parts book for the 0 235 bearings. This is only and E series issue and only the ones I listed have the 0 235 bearings. It is easy to pick out in the parts book because the 0 235 nose bearing is four piece vs two piece on all others.
Click to expand...

Is this parts book readily available? Can you supply a name and/or ID number? I'd really like to get a reference for things like this.

thanks!
 
The Wikipedia page for the Lycoming O-320 explains the differences between the various models as well. If you have a later model you'll have to cascade back through the older ones to figure out everything, as frequently the description is "Model X is a Model Y with Z changed", and Model Y itself says something similar, and so on...
 
mahlon_r said:
This document list each engine by model number and gives some specifics about them. It takes a little thinking but you will be able to see which ones use the O-235 nose bearing setup.
http://www.readbag.com/lycoming-textron-support-troubleshooting-resources-ssp110
Mahlon
Click to expand...

Thanks for the link.

Here's the problem I'm having with backtracking through that list:

Ok I'm looking at an airplane that has an 0-320 A2B. So I look at the list:

O-320-A2B
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A2A but with straight riser in oil sump and -32 carburetor.

Ok so now I back track to the A2A and see this:

O-320-A2A
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A1A but with fixed pitch propeller.

My problem is with the word "Same". Same in every way except....what? What did they change to turn the C/S A1A into the F/P A2A?

What got changed in the A1A to get to: "but with a fixed pitch propeller"?

Something MUST NOT be the same with regard to the propeller rig in order to make it an A2A.

Does it mean it has the O-235 nose bearing or is that part of what stayed the "Same" ?

Is the oil line for the prop control missing?

Is the crank the "Same" as on the A1A or is it solid?

Is there a mount for the governor - is that part of "Same" or is that the thing that is different? Or is the mount there but not the governor? Or is the governor there and that's what's meant by "Same"?

I don't know how to interpret "Same" and yet figure out what must be "different".

Sorry for my denseness but this is non-obvious to me.
 
Last edited:
Engines

If you are looking at an EAB, anything is possible. If it is a certified engine the A series should be constant speed capable.
The definitive way to determine this is to pull the prop and look in the front end of the crankshaft. The plug in the hollow shaft engine is similar to a automotive "freeze plug". Convex when installed, it is then struck with a large diameter drift to expand it and lock it in place. This should cause a noticeable dimple in the center of the plug. Also look for a bead of sealant around the perimeter of the plug. Tapping the plug with a heavy brass drift should produce a hollow sound. Solid shaft-no hollow sound.
There were only three E series engines used in production aircraft that had the 0 235 main bearing set up.
For those working with a core, the 0 235 case setup can be converted to a two piece main bearing by removing four dowels and locating two dowels in a different position.
 
jrs14855 said:
If you are looking at an EAB, anything is possible. If it is a certified engine the A series should be constant speed capable.
The definitive way to determine this is to pull the prop and look in the front end of the crankshaft. The plug in the hollow shaft engine is similar to a automotive "freeze plug". Convex when installed, it is then struck with a large diameter drift to expand it and lock it in place. This should cause a noticeable dimple in the center of the plug. Also look for a bead of sealant around the perimeter of the plug. Tapping the plug with a heavy brass drift should produce a hollow sound. Solid shaft-no hollow sound.
There were only three E series engines used in production aircraft that had the 0 235 main bearing set up.
For those working with a core, the 0 235 case setup can be converted to a two piece main bearing by removing four dowels and locating two dowels in a different position.
Click to expand...
Sounds silly, but make sure the crank is hollow *and* drilled/ported for oil. I saw an -E2A that was not.
 
Saville said:
Thanks for the link.

Here's the problem I'm having with backtracking through that list:

Ok I'm looking at an airplane that has an 0-320 A2B. So I look at the list:

O-320-A2B
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A2A but with straight riser in oil sump and -32 carburetor.

Ok so now I back track to the A2A and see this:

O-320-A2A
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A1A but with fixed pitch propeller.

My problem is with the word "Same". Same in every way except....what? What did they change to turn the C/S A1A into the F/P A2A?

What got changed in the A1A to get to: "but with a fixed pitch propeller"?

Something MUST NOT be the same with regard to the propeller rig in order to make it an A2A.

Does it mean it has the O-235 nose bearing or is that part of what stayed the "Same" ?

Is the oil line for the prop control missing?

Is the crank the "Same" as on the A1A or is it solid?

Is there a mount for the governor - is that part of "Same" or is that the thing that is different? Or is the mount there but not the governor? Or is the governor there and that's what's meant by "Same"?

I don't know how to interpret "Same" and yet figure out what must be "different".

Sorry for my denseness but this is non-obvious to me.
Click to expand...

The O-320-A series is cs capable as far as the nose bearing and crankshaft go. Make sure there is a pad to mount the gov drive too, on the back of the engine and you also might have to change prop mounting lugs in the flange to fit a Cs prop and you will have plug the back of the nose bore in the shaft if it has been being used for FP. Other than that you should be all set.
Merry Christmas,
Mahlon
 
Narrow Deck rocks!

Saville said:
Thanks for the link.

Here's the problem I'm having with backtracking through that list:

Ok I'm looking at an airplane that has an 0-320 A2B. So I look at the list:

O-320-A2B
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A2A but with straight riser in oil sump and -32 carburetor.

Ok so now I back track to the A2A and see this:

O-320-A2A
150 hp (112 kW) at 2700 rpm, Minimum fuel grade 80/87 avgas, compression ratio 7.00:1. Same as A1A but with fixed pitch propeller.

My problem is with the word "Same". Same in every way except....what? What did they change to turn the C/S A1A into the F/P A2A?

What got changed in the A1A to get to: "but with a fixed pitch propeller"?

Something MUST NOT be the same with regard to the propeller rig in order to make it an A2A.

Does it mean it has the O-235 nose bearing or is that part of what stayed the "Same" ?

Is the oil line for the prop control missing?

Is the crank the "Same" as on the A1A or is it solid?

Is there a mount for the governor - is that part of "Same" or is that the thing that is different? Or is the mount there but not the governor? Or is the governor there and that's what's meant by "Same"?

I don't know how to interpret "Same" and yet figure out what must be "different".

Sorry for my denseness but this is non-obvious to me.
Click to expand...

Saville,
The 0-320A "Narrow Deck" series is a great engine that originally came out in early Piper Apaches. As originally configured, they were set up for constant speed with a hollow crank and the governor on the accessory case. There are 2 CS propellers that work well on this engine, the Hartzell sold by Van's and the MT 2 blade.

I installed an A2A in my RV4 back in 95' and flew it for 1000 hours with 2 different FP props with the crank plug installed. The A2A was installed in Tri-Pacers and Early Cherokees with FP props with a governor pad cover and crank plug installed. Most A's can accept a CS simply by installing a governor with oil line and removing the crank plug. They are slightly lighter than the D and E series, have conical mounts and with a Carb are STC'd in certified airplanes for MoGas.. The downside of A's is they are not recommended to install the 8.5:1 pistons (160HP)as the Crank Case "through bolts" are smaller than the wide decks (D,E) and most guys I have talked to with Mahlon's level of expertise say no. Also, they have been out of production since the early 1960's so Cases are getting harder to find.

I removed my 0-320A after 1000 hours in lieu of a rebuilt "E" series 0-320 with 9.0:1 pistons/balancing and "redneck flow matching" (170HP). Performance did improve slightly, but not as much as you would think.

A light "0-320A" powered RV4 performs very well. Parts are readily available for the 'A's" and there are still quite a few on Barnstormers, usually less costly than Wide Decks.

V/R
Smokey
 
Last edited:
mahlon_r said:
The O-320-A series is cs capable as far as the nose bearing and crankshaft go. Make sure there is a pad to mount the gov drive too, on the back of the engine and you also might have to change prop mounting lugs in the flange to fit a Cs prop and you will have plug the back of the nose bore in the shaft if it has been being used for FP. Other than that you should be all set.
Merry Christmas,
Mahlon
Click to expand...

Mahlon,

Thanks very much for the information. We got a little sidetracked:

My original question was about an E series engine. But the questions I've quoted above really go for ALL O-320 engines:

Is there a way of knowing how the engine is configured by reading the nomenclature?

My questions above go equally well for an E1A and E2A...B1A and B2A....etc.

Ignoring the EAB aspect of engine changes, is there some way to know what any particular engine come siwth/has provision for?

thanks
 
The only real definitive way would be to check the nose bearing and accessory housing set up in the parts book. Or just email me or a engine specialty place and ask.
Merry Christmas,
Mahlon
 
Bearings

The low compression wide deck parts book shows the following:

0 235 front main bearing configuration:
O 320E2D Cessna 172 and 177
O 320E2G Grumman AA5
O 320E2H no US production aircraft
O 320E3D Piper PA28-140 and Beech B19
O 320 E3H no US production aircraft
O 320A2D Citabria 7GCBC and 7GCAA

As I posted previously, if the case is split the front main bearing may be reconfigured by removing 4 dowels and installing 2 dowels in another location.
 
You must log in or register to reply here.
Back
Top