----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----Eliacim,
I had something similar happen to me, although you could hear the engine run a bit rough too. The problem was a stuck valve. Once we got it unstuck, the power fully developed and there was no problem. I would check the valves to make sure that none of them are hung up.
In a previous message on the net, Maynard Smith, (530) 637-5115 indicated that he could walk a person through the rope trick. It is pretty easy and quick to do. I've had it done a couple of times to a value that was cantankerous, but I had to have assistance--I'm mechanally challenged.
Just a thought. Hope you get it together so you can fly to Terrell, but we look forward to seeing you regardless.
Ken
Deland, Fl
Leaving for Terrell this morning
At 12:45 AM 6/21/2006, heavensounds wrote:
----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----Thanks to all who have so far provided advice. I truly appreciate this group's willingness to help.
Summary of the problem: Perfect run up at 2000 RPM with small mag drops, but the engine does not develop max power. (Please trust me when I say that it is NOT developing full power). This is after pulling out and back in a cylinder to fix a helicoil and after replacing the magneto harness and the right magneto's impuse coupling and drive gear. And after installing 4 new shielded plugs (top).
Another symptom I noticed is that after a little while (engine is warm?) attempting maximum static RPM (on the ground), the indicated RPM max out at 2000 and then over a period of a few seconds slowly drop to 1800 indicated, and stay there. All those readings are in the plane's tach which reads higher than a more trustworthy handheld optical prop tach. So the true RPMs are lower than the numbers I quoted above.
In response to all your recommendations, we did the following today:
1. Checked mag timing. It was good, but we fine tuned it to exactly what the Continental C-75 manual calls for: 28 degrees before TDC on right and 30 degrees before TDC on left. The problem stayed the same.
2. Checked compression on all four cylinders. All were good.
3. Checked throttle, carb heat and mixture links and range of travel. All good.
4. Checked all 8 spark plugs on a Champion tester. All sparked good.
5. Cleaned the four bottom plugs, which were not new (the 4 top ones are new) and showed some carbon deposits.
6. Replaced one of the bottom plugs with a new one (the thread was not in nice shape). So now I have 5 new plugs out of 8.
After all of that, the problem is still the same!!
What next? Carburetor?
This is becoming a mystery. Any more ideas???
By the way, Ed, the prop is a MC Cauley 1 B 90 CM 7351
Thanks to all
Eliacim
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