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A Tale of Two Engines.... Thoughts?

GrinchF16

Well Known Member
Finally down to two airplanes, a 6A and a 7A. Both about the same age. Both seem to be good builds. Very close in price.

6A - Very nice VFR GRT suite 8/10, good interior 7/10, good exterior 7/10, Titan (no AD yet) engine 500 hours since new but hasn’t flown for 4 years, run monthly.

7A - Basic IFR avionics likely need new GPS/NAV/COMM 5/10, decent interior 5/10, very good exterior 9/0. Engine has “old” core and 500 SMOH but flies at least monthly.

Very limited time in RV’s but fairly experienced pilot. Very interested in your thoughts on the engines. Please share your perspective...
 
"Run monthly" but not flown is scary to me. Engines need to be run up to operating temperatures to allow water in the engine to evaporate (just to be clear - oil temps don't need to be at the boiling point of water, just normal operating temps so water evaporates quickly).

Lycoming engines (and clones) are prone to cam/lifer corrosion if not run at normal operating temps regularly. A few years ago a partner and I bought an Archer with an O-360 that had just completed an IRAN (engine teardown, inspection, replacement of parts as necessary) for corrosion (with replacement of cams/lifters) because the owner hadn't flown the airplane for about 1 year before deciding to sell it. It only had about 250hrs SMOH at the time of the IRAN.

No matter which one you choose, I'd advise a careful pre-buy inspection by an A&P who knows RVs. Check out Vic Syracuse's book on pre-buy inspections to get an idea what to look for/at.
 
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Very limited time in RV’s but fairly experienced pilot. Very interested in your thoughts on the engines. Please share your perspective...
If you can, get a prebuy inspection done by someone like baselegaviation.com. They will help you identify potential "big" issues that may not be obvious to a first-time RV buyer.
 
Finally down to two airplanes, a 6A and a 7A. Both about the same age. Both seem to be good builds. Very close in price.

6A - Very nice VFR GRT suite 8/10, good interior 7/10, good exterior 7/10, Titan (no AD yet) engine 500 hours since new but hasn’t flown for 4 years, run monthly.

7A - Basic IFR avionics likely need new GPS/NAV/COMM 5/10, decent interior 5/10, very good exterior 9/0. Engine has “old” core and 500 SMOH but flies at least monthly.

Very limited time in RV’s but fairly experienced pilot. Very interested in your thoughts on the engines. Please share your perspective...

Neither go tailwheel. If you flew a viper you can land a tw airplane! I’d get a pre buy done on the 7A and go from there. If you’re in love w the 6A, then have one done on that but I too would be considered with it not flying so long. Is it on a engine dehydrator or similar?
 
Price

Depends on the cost of each aircraft and what you're willing to spend after buying the plane. The 7a sounds like it needs some panel work. The 6a might need some engine work.

Is there a concern with the 7a having an "old core" thats been overhauled? We all like to see brand new engines, but in practice is that really that important?
 
Add $15,000 to the purchase price of either plane for possible things that might go bump in the night. That way you will be mentally prepared for what ever.
You might get 10 hours out of the engine or a couple of thousand.
 
Neither go tailwheel. If you flew a viper you can land a tw airplane! I’d get a pre buy done on the 7A and go from there. If you’re in love w the 6A, then have one done on that but I too would be considered with it not flying so long. Is it on a engine dehydrator or similar?

Thanks!! I would like to get my tailwheel endorsement. Unfortunately, mission dictates tricycle on this one. I know an awful lot of Eagle guys that fly tailwheels, it can't be that hard!
 
If I understand things correctly, an RV-6A was built old-school. The RV-7A has parts which are considerably closer to being interchangeable than the older design RV-6A. In the event of difficulties, that might be beneficial.

More immediately, it might be useful if you wish to consider building up a replacement panel.

And there are nearly four times as many RV-7/7A posts here on VAF than there are RV-6/6A, giving a greater reservoir of information.

Dave
RV-3B, definitely an old-school airplane.
Now configuring the cockpit. Started 2012.
 
From my perspective build quality and airframe condition matter more than avionics or engine.

Avionics become outdated and get replaced. Engines get used and rebuilt/replaced (be it high or low utilization). A solid airframe is the common point between both.

If the bones are good use avionics, cosmetics, and engine health to get to the right price.

A side note on engines - buying a plane with a runout engine is preferable to me, provided of course the purchase price reflects the runout. That runout tag could be either from hours or age (if it sat). If you get lucky and the engine is fine, congratulations, you just saved some money. If the engine needs replaced soon after you bought the plane, well it was priced in and now you have a new engine that you know everything about.
 
Thanks!! I would like to get my tailwheel endorsement. Unfortunately, mission dictates tricycle on this one. I know an awful lot of Eagle guys that fly tailwheels, it can't be that hard!

What about those who fly planes that aren't named after animals? Chipmunk, Beaver, Otter, Caribou, Buffalo, 2xOtter. Then they ran out of animals and went with -7, -8... Well I suppose the first 3 already know how to fly a tailwheel.

The other benefit of a runout engine is putting in the engine you want. A -320 can be replaced with a -360, solid crank vs hollow crank. Even small things like changing compression ratios, 150hp turns into 160hp easily.
 
All, thanks for the words! Went with the 7A! Very excited but, not gonna lie, fairly nervous as well. Now starting the pre-buy process. Airplane flies very nice, very snug fit, the story on the engine, assuming it’s accurate, is encouraging, I’m not a builder so can’t speak to that although the wings did stay on, paint looks good, avionics... well, not so much. Once I learn how things tie together I should be ok but I sense I will be reaching out for a lot of help.

Again, thank you guys for the guidance. Well done!
 
All, thanks for the words! Went with the 7A! Very excited but, not gonna lie, fairly nervous as well. Now starting the pre-buy process. Airplane flies very nice, very snug fit, the story on the engine, assuming it’s accurate, is encouraging, I’m not a builder so can’t speak to that although the wings did stay on, paint looks good, avionics... well, not so much. Once I learn how things tie together I should be ok but I sense I will be reaching out for a lot of help.

Again, thank you guys for the guidance. Well done!

There are some very good panel-building companies, very well-suited to those looking to rebuild their panel or start it over. My first choice would be Advanced Flight Systems, mainly because of the modularity they build in, and especially because of their Advanced Control Module concept. Other option might be Aerotronics, and SteinAir.

https://www.advancedflightsystems.com/advanced-panels.php
 
You did not mention price?
Also who is selling so I can steal them out from under you. ::)
Kidding not in market.

If just going just on engines (assume same HP, accessories, Prop) I'd go with newer engine. Infrequently used or parked 4 years, does not concern me with good compression, bore scope and flight test. As mentioned starting ground run only is debatable as to doing any good or even being detrimental. You need to get the engine to full operating temperature for at least 15-30 minutes, which means 75% power in flight, to burn out all the moisture.

More important factors is climate and if hangered or not. If the plane is in a dry climate this really isn't an issue. Also starting the engine is where most of the wear happens. It's debatable whether ground runs every month is a good thing or not but it does keep an oil coating over the cam which can corrode. It shows they care. Dud tgey log it?

A rebuild? Do they have good records of that? What was done by who. An original Lycoming first run out and a good overhaul is a good engine. Flown once a month really isn't that frequent. But as I and others have said getting it up to full temperature is good for the engine. I owned a 1958 Piper Apache for 3 years in early 1990's (DON'T laugh, great plane and same airfoil as RV's). I flew it almost everyday and had over +2200 hours on the engines when I sold it.. running strong, good compression, with nominal oil use. I bought it with 1800 hrs on engines, and previous owner flew it often. I'm convinced daily flying kept those engines in good health.

Both of these RV engines are low use. However good inspection and test flying should tell the story. Again it is all about corrosion. If one was based in Arizona and another in a damp climate the dry engine would have in theory less potential corrosion.

PRICE. That is a factor.

MAUNTENCE records?

RV6 vs RV7 both good and you can look up the specs... RV7 has more range. The RV7 has higher gross weight. RV7 has pre punched kit. However I built an RV6 and an RV7. I can tell you a well-built RV6 is as good as a seven. However the hole patterns were laid out by the builder in the RV6, where the RV7 the holes are pre punched and exactly the same in every airplane. In theory that might make rebuilding or replacing parts easier on a RV7.
 
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