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Problems with installing O320-B2A in an RV-6A?

B

Badger

Member
I'm engine shopping for my RV6A under construction now. Does anyone on VAF have experience with installation of an O-320 B2A in an RV-6A? Need to know if there are interference problems with the nose gear mount or similar. Or will it fit Vans standard nose dragger mount (conical) for RV6A, without requiring modifications? This B2A engine is equipped with the vertical updraft sump and plugged hollow crankshaft. From photos, it looks like the prop governor pad is on the front bottom of the engine case.

Also, the B2A uses 3/8ths inch prop bolts/bushings. Can the bushings in the crankshaft flange be changed to 7/16th bushing/bolts, to allow use of various props (including Cato) that use the 7/16ths mounting bolts? Or does a crankshaft with a larger diameter flange have to be installed to accommodate the 7/16ths prop bolts?
 
Engine

Probably a Piper Tri Pacer engine, high compression version of O 320A. Prop bushings are easily changed, some threaded rod and nuts, stack of washers and/or some sockets that the threaded rod will pass thru. IIRC you only have to draw the bushings part way out of the flange. Prop bushjings are quite expensive.
This engine is likely a narrow deck engine, some parts are hard to find and only available used. It most likely has lightening holes in the crank flange and possibly a thinner crank flange. It would be best to use a wood prop with this.
Never saw a prop governor pad on the bottom, they were either on the accessory case or on the left front side of the crankcase.
 
$_57.JPG

Found a picture of one showing front bottom of B2A. What is that bottom case mount, just behind the prop flange for???
 
jrs,
The pic I posted shows the forward bottom 'mounting pad' on the B2A. If not for the prop governor, then... what? Also, the prop flange is solid, no lightening holes. I haven't committed to either fixed pitch or controllable pitch props yet, but would like to have the option to start flying with a fixed pitch and move to CP prop later.
 
AZ___Gila,
Thanks for the bushing info! Any thoughts/knowledge to share on O-320 B2A install in RV-6A?
 
William,
Thanks for the reply! Did you use Vans standard conical engine mount for your B2A RV6A??

Can you share pics of your engine install? I'm about 85% complete on wings. Tail feathers need fairings yet. Fuselage is at the 'big canoe' stage, rotisseried on a streeeeetch model Harbor Freight 'engine' stand.
 
Badger said:
William,
Thanks for the reply! Did you use Vans standard conical engine mount for your B2A RV6A??

Can you share pics of your engine install? I'm about 85% complete on wings. Tail feathers need fairings yet. Fuselage is at the 'big canoe' stage, rotisseried on a streeeeetch model Harbor Freight 'engine' stand.
Click to expand...

Yes, stock conical mount from Vans. I won't be at the hangar till Wednesday. I'll take some firewall forward pics this Wednesday if you still need them.


Best regards
Bill
 
William said:
I've got a O320-b2a on my RV6A. No problems with the install.
Click to expand...

I am using a conical mount O-320 B2B narrow deck converted to Constant Speed operation on my RV-6 (tailwheel). The engine I have or rather the oil sump used on my engine would not work on the A model. The updraft carb is mounted as far aft on the sum as Lycoming can put it. IF you have a sump where the carb is mounted in the middle, it should work.
 
The issue with the engine fit for an "A" model is if it is vertical induction, it must have a straight riser sump as is shown in the photos posted in this thread.
A straight riser sump uses induction tubes (risers) that have only one bend in them (from horizontal to vertical). If any of the tubes have two bends, it means the carb. is mounted far aft on the sump as Gary described, which will interfere with the nose gear.
 
I acquired an O-320-B1A for my 6A. My sump had the carb attached at the rear of the sump, not the middle. I was told this would not work with the 6A, so found a used sump off a D series engine and sold mine on ebay for around the same price. I don't know if the stock sump would have worked, as my engine was in pieces at the time and could not check. My B series had the standard mounts. Are you sure yours are conical? I had mine machined to conical for $200 when ECI was overhauling the case.

Larry
 
RVbuilder 2002,
Got it. Single bend induction tubes ---> center mounted carb _-----> no interference on 6A mount or nose gear. Thanks!
 
lr172,
The engine I'm considering appeared to have no 'angle' to the engine mount tabs or the machined tapered recesses for the elastomer bushings. I'll double check....

Thanks for the feedback!
 
Badger said:
lr172,
The engine I'm considering appeared to have no 'angle' to the engine mount tabs or the machined tapered recesses for the elastomer bushings. I'll double check....

Thanks for the feedback!
Click to expand...

It has to have one or the other...

The conical mount case has holes aligned with the crankshaft that do have recesses for the rubber bushings.
The dynafocal cases have flat surfaces on the rear, machined at an angle and no recess at the aft side of holes.
 
rvbuilder2002 said:
It has to have one or the other...

The conical mount case has holes aligned with the crankshaft that do have recesses for the rubber bushings.
The dynafocal cases have flat surfaces on the rear, machined at an angle and no recess at the aft side of holes.
Click to expand...

Sorry, my bad here. My B1A was a conical that I had converted to Dynafocal. My brain wasn't fully engage when posting earlier.

Larry
 
rvbuilder2002 said:
It has to have one or the other...

The conical mount case has holes aligned with the crankshaft that do have recesses for the rubber bushings.
The dynafocal cases have flat surfaces on the rear, machined at an angle and no recess at the aft side of holes.
Click to expand...

rvbuilder2002,

Poor wording on my part. The case has tapered recesses on each side of the mount tabs. The recesses are not 'angled' in. All appeared to be straight; e.g. each mounting bolt would be parallel aligned to the others.... and the crankshaft.
 
lr172 said:
Sorry, my bad here. My B1A was a conical that I had converted to Dynafocal. My brain wasn't fully engage when posting earlier.

Larry
Click to expand...

Larry,
Can you tell me why you had the conical case modified to Dynafocal Type I mounts?

I think you said the engine was rebuilt by ECI. Was the engine disassembled when the modifications were made to make it a Dynafocal I mount? How was this done?
 
Badger said:
Larry,
Can you tell me why you had the conical case modified to Dynafocal Type I mounts?

I think you said the engine was rebuilt by ECI. Was the engine disassembled when the modifications were made to make it a Dynafocal I mount? How was this done?
Click to expand...

The partially completed kit that I purchased had a dynafocal mount and I preferred this, as I was led to believe that they isolate vibration better. I overhauled the engine myself and as part of the process, sent the case to ECI for re-work (case edges milled flat and a line hone) and inspection. To convert to Dynafocal, they weld up the original holes then mill angles in the four ears and drill new holes at the appropriate angle. They only charged me $200 while my case was there for the other work. This is a fairly common case modification.

Larry
 
Sumps

The sump with the bottom aft mounted carb has a separate oil pick up tube that bolts to the accessory case. Changing to the horizontal oil screen sump requires removal of the oil pickup tube and modification of the accessory case with a cover plate installed where the oil tube was removed.
 
jrs14855 said:
The sump with the bottom aft mounted carb has a separate oil pick up tube that bolts to the accessory case. Changing to the horizontal oil screen sump requires removal of the oil pickup tube and modification of the accessory case with a cover plate installed where the oil tube was removed.
Click to expand...

You also have to remove a plug in the accessory case. Fab'ing a cover plate and pulling the plug only took an hour. Be sure to use crush washers on the plate, as the original pickup tube uses. It is a pretty easy modification.

Larry
 
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