Lycoming io-360-C1C low static run up / high MP

Is there another (known) fixed pitch prop you can bolt to the engine to see if the engine will turn that prop at the appropriate static RPM?

If not, what was the experience with the first 150 hours on the engine? If the cam is a tooth out of time, it was a tooth out of time before too, and performance would have suffered in that application as well.
 
Was it Catto that told you to expect 2300 RPM?
 
Sounds like the prop’s too course. Does it wind up higher in flight?
 
DaleB said:
Was it Catto that told you to expect 2300 RPM?
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I have seen other posts about this prop/engine config that people have gotten 2250 and gone with it, but was very slow down the runway and on climb out.
 
If nothing else, Lycoming has a tech support line that is a direct number. I'm sure you can find it via Google. I've used that line a couple of times and have gotten excellent advise. You might give them a call and see if there is any way to check the cam timing without removing the engine and the accessory housing. It may be that you could get a peek at the marks through a mag hole using a borescope. Beyond that, with some precision measurements, you could compare crank position and valve timing to see if the relationship is correct.
 
Pilottodd1997 said:
I have not flown it based on Scott indicating its a definite NO GO. It comes up slightly on fast taxi, but not to a point i intend to leave the ground with it. I am sure it would, but something is off.
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Good call.

I assume you’ve checked for muffler and intake obstruction and all that kind of stuff. And with that, I’m out of ideas other than possibly a cam issue. Off a tooth or worn lobes… either one could make it run smoothly but lack power, right?

And I’m NOT an A&P or anything close to it.
 
kyleb said:
If nothing else, Lycoming has a tech support line that is a direct number. I'm sure you can find it via Google. I've used that line a couple of times and have gotten excellent advise. You might give them a call and see if there is any way to check the cam timing without removing the engine and the accessory housing. It may be that you could get a peek at the marks through a mag hole using a borescope. Beyond that, with some precision measurements, you could compare crank position and valve timing to see if the relationship is correct.
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That is my thought tomorrow. There is a procedure to check it without timing marks, or at least get an idea. Its not terrible to take apart and correct if required, but had hoped not to have to. I have used lycoming tech before, and they are pretty good, for sure. I guess my biggest question, if anyone has knowledge, is if it is off a tooth, would that actually cause my issues?
 
Pilottodd1997 said:
Appreciate the thoughts. Exhaust on it is straight pipes, so no obstruction. (points out the rear being a pusher / common straight piped). Took apart entire fuel system, though not much to it, and found crud here and there, but no increase in MP. Runs WAY better now, incredibly good actually, but no upper end. I am reasonably certain the lobes are good... anything is possible, but only has 145 hours or so and solid compressions... all 78/79 of 80. I have never seen one, that I know of anyway, off a tooth. Not sure how it would react? I ran the scope up the intake and didnt see anything there too.
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There was a local around here who had a Cherokee with the cam off a tooth. I think he posted on this board back in the day - probably 15 years ago. His RPM were down, but I don't think anywhere near what you describe.
 
kyleb said:
There was a local around here who had a Cherokee with the cam off a tooth. I think he posted on this board back in the day - probably 15 years ago. His RPM were down, but I don't think anywhere near what you describe.
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I am missing 250 or 300 RPM..... pretty dramatic. Its just odd because it runs best of any 360 I have owned, which has been many. I am sure it would come up in flight, but its just a no go. I will see tomorrow I guess, just hitting my head on the desk tonight trying to think of anything else. They are so simple....
 
Is the prop you actually have and the prop that the prop Mfg thinks you have the same? Sorry for the stupid question, but just ruling out a possibility. Any chance the prior owner tried to adjust the blades to a coarser pitch?

On the engine side, before a complete dismantling: I’m an automotive engine guy, not A&P, so excuse the ignorance if this is not possible - if you can get the cam specs, like lobe lift and duration, you could pull a valve cover and use a dial indicator to confirm timing. You could also check for lobe wear by checking lift on all valves (I think sometimes lobes are shared?). This assumes the lifters are not hydraulic, but you could always pull a valve spring and replace it with a light spring to not compress the plunger on the lifter for checking purposes.

Hope this helps, but if it didn’t, hope it was at least entertaining.
 
My first thought is to verify valve timing by rocking at TDC at one jug

and observing rockers on another.

You may also want to check Dry Lifter Clearance which may reveal a few things.

Might be good to get an idea before any disassembly.

Every “ flat” hydraulic lifter will cause some power loss.

You may find the pushrods are too short also.

With either of these conditions the valve will open later, open less and

close earlier.

There are folks that have cylinders off and do not check this when reassembled.

I once replaced 6 pushrods on a Super Cub to get proper DLC.

This resulted in a 150 rpm increase in Static RPM.

This aircraft had been in the family for many years.

The mother of the 70 year old pilot remarked , “ It never sounded this good!”
 
Pilottodd1997 said:
Any thoughts?
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What altitude or DA are you checking this? Usually lack of static RPM is elevation or prop issue or possibly mismatched in your case. I'd confirm the prop is set correctly and if checking at above sea level correct your target. Did you try leaning at max RPM to see if it changed?
 
Pilottodd1997 said:
Yes, Catto said 2200 to 2300 at least on static and 2800 WOT in flight. It is a right in the middle prop, pitched 69/72.... shouldn't be hard to swing it and it is specifically for this engine, horsepower and plane.
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Craig seems to know his business very well. He told me where the RPM would be and he was right.
Are you sure your RPM is correct?

This was mine that did around 2200 static if I recall.
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FORANE said:
Are you sure your RPM is correct?
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A very good question. Lots of tachs are old and reading low.

Worn cam should result in some roughness. The lobes don't all wear evenly. Short pushrods or flat lifters should create lots of clatter.

I checked the Lyc DD overhaul manual. Couldn't find the cam/valve movement specs. Saw them somewhere long ago.

I would recheck that mag timing. I would make sure that the timing marks on the flywheel are where they should be. Lyc hasn't always been that accurate that way.

And don't get caught by the confusion between mag timing boxes. The old buzzbox type had its lights come on when the points opened. The newer electronic ones usually have the lights go off when the points open. I saw a couple of fellow mechanics fight with a low-RPM situation for a week or more due to that. I kept suggesting that the timing be checked again, carefully. Think it through. See what the mag timer does when you put its clips together. Read the label on it.

Does the static RPM come up if you lean it some?
 
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Dan Thomas said:
A very good question. Lots of tachs are old and reading low.

Worn cam should result in some roughness. The lobes don't all wear evenly. Short pushrods or flat lifters should create lots of clatter.

I checked the Lyc DD overhaul manual. Couldn't find the cam/valve movement specs. Saw them somewhere long ago.

I would recheck that mag timing. I would make sure that the timing marks on the flywheel are where they should be. Lyc hasn't always been that accurate that way.

And don't get caught by the confusion between mag timing boxes. The old buzzbox type had its lights come on when the points opened. The newer electronic ones usually have the lights go off when the points open. I saw a couple of fellow mechanics fight with a low-RPM situation for a week or more due to that. I kept suggesting that the timing be checked again, carefully. Think it through. See what the mag timer does when you put its clips together. Read the label on it.

Does the static RPM come up if you lean it some?[/




I have dual pickups for the tach, going to EFIS. Both tach inputs are the same, and then verified with optical tach. Thats out.

Engines runs smooth as glass, just lays down at 2000.

Used dead stop method on mag timing. Tried it at 20, 25 and 30 degrees, with nearly zero respective change and NO rpm difference, and mag drop is less than 30rpm between them at 1700 and non existent at 2000.

I am in Charleston, SC.... below sea level if anything haha. And 35 degrees outside.

Cam is new 145 hours ago.... but I know that doesnt mean anything, per say. Compressions perfect.
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We did the test above, and believe its correct. Now I am more stumped. Sometimes its better to have a PITA problem and know it rather than not knowing. o_O
 
I'd verify Tach. Then look at mags then timing...unless the prop ain't what it says it is
 
Does it hit 2000 RPM before the throttle is all the way in?
 
Dan Thomas said:
Does it hit 2000 RPM before the throttle is all the way in?
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Yes. 2000 is reached about 65% throttle. Then stops. Pulled engine, removed the accessory case, and verified timing marks. All was correct. Waiting on gaskets tomorrow to reassemble. There is no meaningful change in anything after 65%.... I did a high speed taxi before removing, and gained about 30 RPM by 60kts.... I didnt go any faster as thats nearly rotate... and runway length of course.
 
Also, dual pickups on the tach... both read same. One fail, maybe... 2.... ehhh. Sort of back to the drawing board. Prop from Cato, has sticker with engine and HP, and other data. Hard to imagine its just wrong, especially when cato confirms it. Also its 7 years old, and new to me... im told it flew fine before with it. Maybe people ignored the low RPM and it comes up in flight?? Seems risky, at best.

while engine off, took manifolds apart, why not, cleaned inside out, found nothing.
 

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What a way to spend a day... to learn its correct. haha
 

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Anyone have a 2 bladed pusher prop that is suitable for sale? Or trade? 64/70 I am thinking.
 
Just a thought… have you verified that the throttle cable actually opens the throttle all the way?
 
DaleB said:
Just a thought… have you verified that the throttle cable actually opens the throttle all the way?
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yeah, its 100% ...no questions there. Appreciate all the input... I think I have a prop that just is too much for the engine, despite being told its been on there for quite a while. Looking for a two bladed one now, I think.
 
Do all your troubleshooting first!
 
Confirm valve and mag timing,

Oops didn’t see you pulled case.

Lifters?
 
Pilottodd1997 said:
Looking for a two bladed one now, I think.
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If it's a pusher, a 2 blade might lead to harmonic issues as both blades pass through the wing blank. At least this is what I hear the reason many pushers use 3 blades...
 
Pilottodd1997 said:
Yes. 2000 is reached about 65% throttle. Then stops. Pulled engine, removed the accessory case, and verified timing marks. All was correct. Waiting on gaskets tomorrow to reassemble. There is no meaningful change in anything after 65%.... I did a high speed taxi before removing, and gained about 30 RPM by 60kts.... I didnt go any faster as thats nearly rotate... and runway length of course.
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Sounds like too much prop. What airspeed is this airplane supposed to cruise at?
 
My IO-390 makes full power at about 60% throttle. The only thing that changes beyond that is fuel flow goes up about a gallon per hour. Not a problem in itself.
 
Interesting outcome to say the least. I was thinking it was the prop. Appreciate you closing the loop on this.
 
Pilottodd1997 said:
This engine had a Landoll harmonic balancer for the prop on the tail.
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Curious. By “on the tail” you mean the balancer was mounted on the starter ring gear of the aft facing engine? Was it the fluid type or solid type? Is there a spacer used between the crank flange and prop?
Pilottodd1997 said:
The balancer, purportedly, is for only 2 bladed props and NOT required or recommended for 3 bladed.
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FYI: The balancer can be used with any engine/prop combination. I’ve dynamically balanced a number of aircraft with it installed to include 3 bladed props but not on a pusher. However, the intent of the balancer was/is to reduce torsional forces on the drivetrain and not radial imbalance per se. So it doesn’t matter on the number of blades. It was also touted to affect engine RPM which was a hit or miss result, but hanging a 12 lb+ chunk of steel on the crank has to have some effect on engine acceleration/deceleration. So by removing it you may have altered the dynamics enough to allow the engine to speed up with that light-weight prop you installed. A number of people installed either the solid or fluid type Landolls for CG purposes more than performance purposes. There was also a separate steel ring available to use with the fluid ones for certain ops.
Pilottodd1997 said:
I can tell you that without it, all of my issues went away.
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While this may be apparent, you may still want to check the prop pitch setting to make sure it matches your engine/airframe configuration. If I recall correctly, the Cotto’s could be a bit sensitive to this airframe/prop setting.
 
Pilottodd1997 said:
Hey guys. So, just to post my findings....

This engine had a Landoll harmonic balancer for the prop on the tail. It came with it and I never questioned it. However, after swapping props and trying everything under the sun, I removed the "balancer" and whooaaaa.... off to the races. My static came up to 2300 and 70% power, and all is good in the world. The balancer, purportedly, is for only 2 bladed props and NOT required or recommended for 3 bladed. While I cannot validate the required/recommended statement, its all hearsay, I can tell you that without it, all of my issues went away.

With that said, I have a very nice, chrome in fact, balancer for w 2 bladed prop that bolts to the flywheel if anyone needs or wants to try it?? I wont ever use it. todd@skywardllc.org
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If you still have the balancer and are interested in selling it, I can link to this post on the Van's forum and I think you'll get takers. Lemme know.
 
Bell206 said:
FYI: The balancer can be used with any engine/prop combination. ...the intent of the balancer was/is to reduce torsional forces on the drivetrain and not radial imbalance per se. So it doesn’t matter on the number of blades.
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Bingo. The balancer dampens the firing pulses of the engine. And adds weight. That's all it does.
 
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