Swapping engine considerations

Hello VAFers - I have a question right up your alley.
I own a 9A with a Lycoming O-320 D1A in it. I am considering an opportunity I have to change engines to a Lycoming O-360 A4A.
Leaving off the discussion of whether or not an O-360 should go on a 9A - I am trying to learn what else I will have to change to make this switch. In other words, what do I need to budget for.
Can I use the same dynafocal mount?
Will my cowl still work around the new engine?
How much weight will my nose gain approximately?
What other costly change am I forgetting to factor in?
Thanks for any words of wisdom you all have.
Tim

You might need a new propeller....

Dave

It will likely not be as easy as you might think. I haven't looked up these specific engines but more than likely there will be some differences in accessory mounting. You can look up the basic engine weights and get an idea of weight difference. Hard to say for sure if your cowl will need modified.....my guess is that it may for air intake...and you may likely have some changes in engine controls. New fuel and oil hoses, (which is easy), etc. I'm thinking the engine mount will work, but no guarantee....see if the part numbers from Van's is the same for your mount verses and RV7a for 180 hp engine...probably is, but idk.
Im sorry I'm not more specific, but it most likely won't be as simple as plug and play. If you launch into it, you should be mentally prepared to deal with unexpected issues.

tcoverst said:

Hello VAFers - I have a question right up your alley.
I own a 9A with a Lycoming O-320 D1A in it. I am considering an opportunity I have to change engines to a Lycoming O-360 A4A.
Leaving off the discussion of whether or not an O-360 should go on a 9A - I am trying to learn what else I will have to change to make this switch. In other words, what do I need to budget for.
Can I use the same dynafocal mount?
Will my cowl still work around the new engine?
How much weight will my nose gain approximately?
What other costly change am I forgetting to factor in?
Thanks for any words of wisdom you all have.
Tim

Click to expand...

never done that swap, but.... yes they are both dynafocal 1 mounts so the mount should work, but check with vans on the part numbers.

the cowl should work, however, the baffling will change and some work may have to be done to the cowl depending on carb, airbox, and induction setup.

the weight difference is about 10 -15 lbs depending on accessories.

due to HP upgrade, your prop may or may-not work with the new engine. the drive lugs may be different sizes the 360 uses a larger drive lug. the prop manufacture may be able to set the prop up for the new engine. also, the pitch of the prop, assuming FP, may not be the best for the larger HP.

depending on the oil cooler installed, you may need to go to a different oil cooler.

due to the different carb, your throttle and mixture brackets and cables may not work with the new setup.

those are just a few things that come to mind.

my personal thoughts are, i would not do it. If your running a FP prop, I would go to a CS prop, long before doing an engine swap.

bob burns
RV-4 N82RB

Been there, done that, oh the fun...

Basic differences between the 2 engines.
Width- the 360 is about 1 1/2” wider than the 320. Look in your cowl & see if there is room for 3/4” more engine on each side.
Height- the cylinders & case are basically same other than the width factor being the cylinders are 3/4” longer. The big difference height wise is that the carb/air filter will end up 1” lower so you will be either changing the lower cowl, or cutting off the existing lower scoop & repositioning it 1” lower.
Air filter- the FAB filter housing will need to be replaced with the larger 360 version. This one is wider, so the scoop not only needs to be the 1” lower, but probably split to make it wider as well. Don’t be afraid of a little bit of glass work, if you are, get a lower 360 cowl.
Baffles- 320 baffle set can be modified to work on a 360 but is overall easier to just get a 360 set.
Exhaust- basically the same but you probably be sending it out to be modified to fit the wider engine.
Prop- definitely a change out here. New spinner too.
Linkage- slight differences here, maybe old stuff works here, maybe new cables needed, only the specific installation will tell.
That’s the basics, if I remembered them all.

Take a look at converting your 320 to a 340 with a stroker crank. May be a viable alternative, & cheaper.

On the RV-8, at least, there are different bottom cowls for the O-320 and O-360...

Great info - thanks

Despite my partial info and hastily composed question - you all have given me some really good info and categories to think about. I am pressing pause on the switch for now, - just too many variables for me at this time, but its good to know the questions and areas I need to think through before undertaking it in the future. I appreciate all the responses.
Happy holidays one and all!
Tim