O-320 B3B for RV-7A

I ordered an engine mount and cowling for an O-360 with a constant speed prop. I found an O-320 B3B with constant speed prop. Will this work if I just order a conical mount? Why doesn't Van's want me to use this engine? Any information will be greatly appreciated.

In my humble opinion the value of the 7 will be higher if you use a 180 horse and CS prop. I built a 7 and would not use a 160 horse for that reason, plus the performance is better.

The 9 most have used a 160 horse. I am interested in a 9 with a CS prop, but very few have been installed. I have seen a 150 horse however on the 9.

You are the builder and it is your choice.
Best to you.
Dave

My RV6A has a O320 B3B. It was flying previously as a stock B3B with the Carburetor in the aft location. The filter air box was pretty hacked up to make it work. During overhaul I changed the sump to the more forward carb. location. Also had a Hartzell prop. but I'm changing to a Cato for lightness and simplicity. Not flying yet...

I use a 0-320 b3b

350 hrs, fp, chrome cylinders, and it is a conical mount. I am pleased with the 160hp performance in my 6. Why doesn't Van want you to use the engine?

Zero4Zulu said:

My RV6A has a O320 B3B. It was flying previously as a stock B3B with the Carburetor in the aft location. The filter air box was pretty hacked up to make it work. During overhaul I changed the sump to the more forward carb. location. Also had a Hartzell prop. but I'm changing to a Cato for lightness and simplicity. Not flying yet...

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Do you know what the part number is on that sump, or what it came off of?

JimWoo50 said:

350 hrs, fp, chrome cylinders, and it is a conical mount. I am pleased with the 160hp performance in my 6. Why doesn't Van want you to use the engine?

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I don't know why they don't want me to use it. He just said they don't recommend that engine for the 7. Maybe vibration?

pastranafan5 said:

I ordered an engine mount and cowling for an O-360 with a constant speed prop. I found an O-320 B3B with constant speed prop. Will this work if I just order a conical mount? Why doesn't Van's want me to use this engine? Any information will be greatly appreciated.

Click to expand...

IIRC, the O-320 B series engine has the carb mounted as far back on the oil sump as it can possibly go. This configuration on the oil sump does not work with the -A model RVs because there is not enough room for the FAB. (FAB = Filtered Air Box)

IF you use a B series engine on the nose wheel RVs, the oil sump most likely will need replaced due to interference with the nose gear. Typically it is easier to just let the tail wheel RV guys buy the B series engines so that there is no interference with the little wheel mount plus no need to try and find a sump and swap it.

My engine builder had the correct sump. I believe there are many different engine models that have the carb. in the more forward location. The one we used also had larger intake tubes. Maybe they all do... Also there is a small modification that will need to be done to the oil pick up location. Plug one hole with pipe plug and drill the oil passage to go downward. I don't remember the details but a very simple modification.

Also there is a Lycoming insert for the carb. intake bore in the sump so the carb. bore matches the sump. Corrects air flow I guess. I don't have the P/N for it but you can search the forum here. I haven't done this yet but I think it is recommended.

I would like to know who told you not to use 0-320. I was told that was a good choice for RV 6 and 7. One of the guys there actually has 0-320 on his personal plane. As far as vibration, the 0-320 seems to me is smoother than the 0-360.

As you probably guessed I have a 7A with 0-320. Have FP wood prop. Very happy with performance. Very smooth. keep in mind that if you go with the 0-320, it does require a different engine mount. I almost made that mistake!!!! The 0-320 engine mount is slightly longer to help with CG.

I would be pretty certain they didn't endorse it because the B series engines have the rear mounted carb, which is problematic. I used an O-320 B1A. I found a sump with the centered carb on Craigs list and sold my old sump on e-bay for almost the same amount of money. No other issues with that engine.

Larry

Ahhhh... gotcha. Mine is a D2B so no problems with different configuration. I am very satisfied with the plane engine combo. Hard to even burn 8 gph cruising. Usually cruising 170 mph on 7-7.5 gph. Probably not as valuable as the same plane with 0-360. I simply couldn't find a descent priced 0-360. 0-320 are much easier to find used. At least that was my experience 2 years ago.