Colt with O-235 C1 It sounds like one cylinder is developing considerably more oomph than the others. When aircraft is at 800 ft you can hear this on the ground. Does make Static but takeoff performance is poor. VERY noisy. Will be doing Spin type compression check and run up with different Colt props and Optical Tach. Could 1 cylinder be off a R-2800 ? More realistic would be from a high compression O-235 L2C or similar. Valve Lash in agenda. Other thoughts?
Will you guys stop it. I'm about to bust a vein in my head. To the OP I grew up watching the Little Rascals and working in my uncles gas station listening to customers mimic concerning sounds from their car so I understood your post. I would suggest for the best conservation of your energy that you check in with these guys. https://www.shortwingpipers.org/forum/
I'd suspect an exhaust leak. Hole in, or loose, manifold, Cracked head. Can't think of a scenario where one cylinder makes more power. For sure I'd not test it in the air.
Exhaust Leak as mentioned above. Bad baffles in yea olde muffler (assuming there is one) also seems likely. Why test with a different prop (if I am reading correctly)? Higher compression cylinder? How would that make it sound louder? Takeoff is poor as compared to what? Valve lash - looking for a bad cam? Shake rattle and roll would be an indication of 1 good, 3 bad cylinders - got that? Compression test (either leak down or compression) can't hurt and is easy to do.
Hahah I heard one of these in the runup box yesterday... Aviation Adventures 172... engine running fine.... increased RPM (ok, he's doing a runup).... then..... BOOM! Too many clicks left buddy, too many clicks left.
“Poor Performance “ is by comparison to Owners previous Colt. It could be 3 weak cylinders and 1 good one for whatever reason. The reason we will try another Prop is that Hangar Fairies have been known to cut tips or re-pitch Props to put Static RPM in limits. Would not affect sound but would affect Performance. “Spin type Comp Test” may show if High Comp Piston is installed in one position. A Leak down check would not. It flew 1000 miles to get here. That may be further than many “Pilots” have ever flown.
I have to quote Dr. Holliday after reading this last post: What browser are you using that makes the text break like that at the most irritating moment? It is almost like a Haiku but not really. But similar because the words just seem to end up on a new line for some reason. Why?
Resolved. BANG has reformed and now the chorus is a normal bing bing bing bing. Plus Static RPM has increased by 50. And the one person that was able or willing to offer suggestions was none other than Capt. GT. Lack of clearance on #3 Exhaust Valve.
And the valve didn't burn?? The O-235 needs the valve clearances checked every 100 hours. It and the O-290 are the only Lycomings without hydraulic lifters. https://www.lycoming.com/sites/default/files/O-235&O-290 Operator Manual 60297-9.pdf
funny thing is, I had no idea where it came from. never saw the chipmunks, if that's where it's from.
We’ll see if burned. Could insufficient clearance cause the Valve to overheat and tulip which would result in even less clearance?
I’m guessing this started with a Intake Leak on #3. Lean mixture caused valve to tulip and lose clearance. Comments?
The valve face and the seat both erode so that the valve ends up deeper in the seat. After a few hundred hours the clearance is gone and the valve doesn't seat firmly enough to transfer its heat to the seat. Hydraulic lifters were invented to make that adjustment.
Deprived. Deprived of history lessons. It's the reason why we see history repeating itself once again.
Yeah, the common misconception many have of engines is that valve clearance gets bigger (cam lobe and follower/lifter wear) as the engine ages, but as Dan explained, the clearance actually gets smaller. This is born out by every motorcycle engine I've ever done a valve check/adjust maintenance.
The other 7 valves are within the .008-.012/spec. I’m thinking all were properly adjusted at one time. Also think Heat ( lean) would be the culprit for reduced clearance on #3. btw Aircraft flew from Missouri to New York & 2hrs Check- our last year.
