Just read MOST of another Ppnked 18x with no reported problems.

Seems to my limited vision that the other X-over tube appeared to be a bit smaller in diameter. To tired to go back for comparison again. Sorry. CC

There are at least three different size balance tubes, and like most builders, Steve has his favorite. I have no idea how much difference it really makes.
To add to the confusion, there are also those that use foam pipe insulation (generally a cold climate deal) on the balance tube. Reportedly it makes quite a difference, as excess fuel tends to fall out of atomization and pool there then pouring into the front two cylinders…We have no cold Wx here, and I tend to cruise with a touch of carb heat on, so I can not speak intelligently to that,

Take care, Rob

Speak to the Man himself and he will tell you to use the smallest diameter balance tube and no need for insulation. The smaller one provides best protection from icing and more room for governor.
John

Ok this is turning from "Pponk troubles" to "Pponk Nightmare".

Ly-con can't find anything wrong with the carb and have never heard of an engine vibration caused by a carb. Neither has Steve Knopp. Next time I'm going to drop the plane off at the shop and tell them to call me when it's done.

Anyone know what to torque the engine to mount bolts to? I have Lord J-6545-1 mounts on our former O-470-K engine. The book is vague and seems to indicate the torque should be the standard value for that size bolt, but Ly-con says the torque should be lower.

Thanks,
Dan

On my R motor the torque value is the standard for the bolt size. Just replaced my forward engine mounts and had to look up the torque spec. Not sure if that's any help, but hopefully.

Yup standard torque for a 7/16 bolt is 450-500 in lbs.
Cessna 200 series books says 480 inlbs or 40+-3 lb-ft.

The torque specs offered above are in line with those for my 185. Just put in an IO-550, and no issues. I doubt torque would be a factor in vibration.

Perhaps attaching a dynamic balancing sensor and analyzing the findings will narrow down the possibilities. A particular frequency corolated to the engine RPM could help focus your search. Trade propellers with a friend and see what happens? Cross firing mags?

Sorry to hear of your frustrations. These things take time to resolve. I can't say I'm 100% satisfied with my IO-550 yet. It doesn't seem as smooth as the old, wore out 520. I'm still trying to decide if it has an occasional miss, or airframe buffet. It makes big power, and translates to thrust through the MT prop, but the EGT spreads and CHT spreads are not satisfactory. When I get home I'll be installing my JPI 930 engine monitor. The TCM tuned injectors are also suspect according to the readings I'm getting off the old GEM analyzer. Gamis may be next.

Good luck. It'll come together. Not every engine runs perfect straight out of the box, but they're not like computers! You'll eventually put your finger on the problem.

I too have never heard of a carburetor causing vibration. I am however familiar with the utter frustration that can arise from unsuccessful trouble-shooting, argh!

What's always worked for me is keeping an open mind and keeping at it, don't be too committed to one hypothesis.

As long as lord mounts are torqued enough to trap the center bushing it shouldn't shake too much. Those bolts on a Seaplanes West mount are torqued 450-500 inch pounds.

Good luck, you'll figure it eventually


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Dan
I have spent enough money on engines to understand that there is a point where a proper gauge will more than pay for itself. If nothing else it tells you what is working so you can move on. Get a proper 6 cylinder EGT/CHT and see what cylinder is causing the problem (or not) and go from there.
DENNY

DENNY wrote:Dan
I have spent enough money on engines to understand that there is a point where a proper gauge will more than pay for itself. If nothing else it tells you what is working so you can move on. Get a proper 6 cylinder EGT/CHT and see what cylinder is causing the problem (or not) and go from there.
DENNY

+1

john54724 wrote:Speak to the Man himself and he will tell you to use the smallest diameter balance tube and no need for insulation. The smaller one provides best protection from icing and more room for governor.
John

Well, as with most things aviation, your mileage may vary if you fly one of these things in ACTUAL cold temperatures. In fact, at very cold temps, these engines just won't run without the crossover tube insulated.....no matter the size of tube.

But, again, I'm talking actual cold temps, not the kind of temps most folks fly in. And, in any case, the insulation on the crossover tube does no harm at all.

MTV

After Lycon couldn't find anything wrong with the carb, I did a quick induction leak test using a vacuum cleaner and bubble soap. Found one small leak around the hose seal on #6 and then a gusher on the hose seal on the balance tube. My IA took the balance tube out and was shocked to see the ends were mashed and the rolled beads beat to heck. He reformed them with a hammer and put everything back together. Runs great now, 3 flights and 4 hours with not a drop of oil used (engine builder supposedly ran it in a test cell). Engine builder was Aero Engines of Winchester VA. They put the front seal in wrong, didn't tighten *at all* the oil adapter, and had multiple induction leaks. Hope that was all they screwed up.

Loren at lycon went the extra mile in trying to troubleshoot this issue.

Oh and a 6 cyl engine monitor would NOT have caught this. Just say'n.....

Sounds like they had the high school kid who normally brooms out the shop do the final stuff! I always worry when simple stuff isn't done right, and I can't see the difficult stuff.

I had to have some body work done on my pickup--a friend I'd lent it to had a sideswipe accident--and when I got it back from the body shop, the body work and paint appeared very good, but they'd removed the box to do the work, failed to redo the wiring to the tail lights properly, and had apparently used a spade to remove my tool box from the box instead of unlocking it from its installation bracket, breaking the bracket. I rewired the tail lights myself and repaired the toolbox bracket, but I asked the Ford garage to check to see if the box was actually bolted down properly. And I sent a letter to the body shop, to which they responded, "we're sorry that you're unhappy" without ever owning that they'd done poor work.

Maybe you should get a discount from Aero for screwing some of the things up, even if they did the rest of it correctly. In any event, that kind of workmanship would make me never use them again, just like I won't use the body shop again, though I'd used them at least half a dozen times in the past.

Cary

Ace007 wrote:Engine builder was Aero Engines of Winchester VA. They put the front seal in wrong, didn't tighten *at all* the oil adapter, and had multiple induction leaks. Hope that was all they screwed up.

Sorry to resurrect an old thread, but I've been trying to chase down issues on my own PPonk (runs fine at low altitude, but up high I have either cylinders 1,2,3 way too lean, or 4,5,6 way too rich). I bought it in January, and the previous owner didn't seem terribly interested in engine management, but the engine was built by the same people as yours. Sounds like they might be a bit of a dodgy operation...

As I'm learning on these engines, a lot of issues can be traced back to induction. Even a slightly loose clamp will lean out the mixture at that point and downstream of it, and cause weird imbalance on the other side of the engine. Many people have magically corrected all kinds of gremlins just by checking those points. This is the first I've heard of a mashed tube, but good job isolating that!

I disagree that a 6 cyl engine monitor won't help catch these things though. You should see odd EGT and CHT spreads; they may or may not be confined to a specific cylinder as well. If a tube is loose between the back and middle cylinder for example, you'll throw the front two out of whack. Something should seem off from the rest, if you have the monitoring to see it.

Regarding balance tube size, Steve's guidance is that the latest model O-470 tubes are the best, as they have a narrow diameter and apparently promote less carb ice somehow. I don't plan to A/B test it, but I'm putting this tube on my Ponk conversion and we'll see how it goes. The EI gauges will give me numbers on basically everything including carb temp. I never really considered insulating the tube beyond that, but I don't see how it would hurt as long as you keep it secure and away from hot exhaust headers.