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  #1  
Old 06-19-2017, 06:16 PM
ssokol ssokol is offline
 
Join Date: Jan 2016
Location: Kansas City
Posts: 15
Default Going back to Concord from Odyssey?

Long time lurker, first time (as an RV owner) poster.

I just purchased an RV-6A with an IO-320 and an Odyssey PC680. LOVE the airplane - having a ton of fun with it. But... The aircraft starts up fine when cold but hot starts are a monumental pain. I've had to have the guys from the FBO come out and jump start me at the pump twice in the past few days. I've tried several different a procedures to clear the vapor lock, but none of them have been a "magic bullet".

The Odyssey (installed last year according to the log book) is only good for 30 - 50 blades before it loses steam and can't turn the engine over. That's not quite enough to clear out either the vapor in the lines (if attempting to start without flooding) or the excess fuel in the cylinders (if trying a flooded start). We're pretty sure it's the battery as it the airplane has no problem starting once the jump pack is hooked up (itself a difficult process - need a ground power plug!).

The battery tray on this airplane is on the firewall, rather than centered inside the cabin. It was obviously built for a 25, rather than the half-sized Odyssey. At some point one of the previous owners switched over and left the full-size tray in place.

I like the size, weight, and cost of the Odyssey but if this airplane needs more juice to start then I'm tempted to eat the 11.5 pounds and go with a Concorde so as not to have to worry about running out of amps at some remote field.

Anyone out there have words of wisdom, warning, or agreement? Am I looking at a complicated W&B issue?

Thanks in advance,

Steve
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RV-6A N101PR
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  #2  
Old 06-19-2017, 06:25 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
 
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No direct answers for you, but...

You might want to find the root of the problem rather than just try to mask it with a battery. PC680's have a long history of outstanding cranking performance on RV's. It sounds like your real starting problems lay elsewhere.

If you do go with a larger battery, to find out if you'll have a W&B issue, you should be able to do the math pretty easy to figure that out. I'm assuming an W&B came with the aircraft when you bought it? Even if it did, the first thing I would do as a new owner was to get a new W&B anyway, just to be sure it reflects the current configuration of the aircraft, not the configuration when it was first built.

Good luck.
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Last edited by alpinelakespilot2000 : 06-19-2017 at 06:28 PM.
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  #3  
Old 06-19-2017, 07:11 PM
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SMO SMO is offline
 
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Ditto on the reply above. A PC680 starts my IO-540 just fine, cold and hot.

Hot start procedure is simple: Throttle full, cycle the mixture once (full rich and back to ICO), crank.

Works every time, never more than 10 blades. Of course once it fires you don't want to dilly dally getting the mixture to ~half and the throttle back to idle.

Maybe you do need a new battery, but if so I would just replace it with another PC680.
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  #4  
Old 06-19-2017, 07:26 PM
Larco Larco is offline
 
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Location: DVT Phoenix
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Right on. Everyone will fine tune their own hot start procedure but NO boost pump part throttle full lean and crank. Once it starts (should be right away) go half on the lean and sometimes it might be necessary to turn on the boost pump (half way to the hanger) AFTER start to keep it running. At least I have to in the summer here in AZ. If the battery is good the 680 probably is not the problem. After 2700 hours in 2 different RVs this works for me and many others that I know. Hope this is helpful?
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  #5  
Old 06-19-2017, 07:33 PM
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JohnInReno JohnInReno is offline
 
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Default W&B

30 to 50 blades should be enough to start any engine. The starting problem is somewhere else.

The W&B issue can be a blessing on an RV4. Mine had a 320, a carbon fiber Prince prop(11 lbs), and a relatively light pilot(170 lbs). Without adding weight to the nose, the biggest passenger I could take was 195 lbs and I had to land before the tanks were half empty.

As others have said, get a new W&B to make an informed decision based on you and your plane.
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  #6  
Old 06-19-2017, 07:42 PM
rv7charlie rv7charlie is online now
 
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One more for 'not the battery'. I put about 200 hrs on a Swift, 1st with an IO-320, then with an IO-360. No hot start problems because I was taught the technique that worked with that a/c.

Charlie
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  #7  
Old 06-19-2017, 08:00 PM
Lynnv Lynnv is offline
 
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Location: Canyon Tx, Park City Ut.
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Anytime I make a stop on a trip in my RV7, I open the oil access door to let the heat out of the engine compartment. The fuel is hot due to the flow divider and fuel lines that are on top of an IO engine. I think this will help your starting problem.
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  #8  
Old 06-19-2017, 08:02 PM
ssokol ssokol is offline
 
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Location: Kansas City
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Thanks to everyone who's responded so far. Sounds like there's a lot of support for the Odyssey, and a pretty strong consensus that there's something wrong with either my starting technique (quite possible) and / or some other aspect of the starting system.

Assuming that there's something off about the starting system, any guess what it could be? I know I've got good spark - one e-mag and one standard, both of which check out fine during run-up. Once it starts it runs well. Full rich fuel flow is higher than I expanded on my experience with an O-320 in a Cherokee, but it doesn't seem to have a negative impact on performance.

Thanks!

-S
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  #9  
Old 06-19-2017, 08:05 PM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by ssokol View Post
The Odyssey (installed last year according to the log book) is only good for 30 - 50 blades before it loses steam and can't turn the engine over.
I've flown PC-680's for fifteen years (RV-6, O-320) and 30-50 blades is a healthy 680! As others have stated, hot start routine probably needs to be refined. The hot injected engines I see usually are running in less than a dozen blades unless the start is fumbled.

I would be concerned about cooking the starter if 40-50 blades were spun in a short period of time especially if you have one of the lightweight, high-current starters.
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Last edited by Sam Buchanan : 06-19-2017 at 08:13 PM.
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  #10  
Old 06-19-2017, 08:25 PM
ssokol ssokol is offline
 
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Yep, my mechanic came out and read me the riot act for cranking longer than 10 seconds and not waiting at least 30 seconds between attempts. Lesson learned!

I've always had carbureted engines before- never needed more than 10 blades. New world...
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