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  #11  
Old 06-29-2014, 07:13 PM
BillL BillL is offline
 
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What kind of exhaust system does this engine have, straight through? or muffler?

If muffler, you also might check to see if it is restricted.
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  #12  
Old 06-29-2014, 07:20 PM
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N941WR N941WR is offline
 
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An engine, any engine, is nothing more than an air pump. Restrict either the intake or exhaust and you harm efficiency.

Add to that the timing and carburetor jetting.

Assuming the hardware is good, it is either going to be restricted intake/exhaust or timing or fueling.

Timing is the easiest to check, so start there.

Good luck and report what you find.
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  #13  
Old 06-29-2014, 09:26 PM
Wyo_flyer Wyo_flyer is offline
 
Join Date: Jun 2014
Location: Lyman, Wyoming
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Thanks for the replies!! You guys are awesome.

It has vetterman straight pipes without mufflers so I think I can rule the exhaust restriction out.

I am leaning heavily towards fuel and timing. Wish I had a buzz box to do my own timing check but my a&p can help me out on that.

I'm going to do a fuel flow at the nozzle test tomorrow with baby jars and check for even fuel distribution at the cylinders. Also going to check all my fuel lines from the tank to the pump to make sure there are no leaks.

I think I'll also pull the valve covers and see if the valves and springs are in good shape.

If none of that changes anything...I think I'll pull the fuel servo and have it flow tested.
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  #14  
Old 06-30-2014, 04:52 AM
F1R F1R is offline
 
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You might also check your fuel pressure. I have seen an IO -360 with .150" worn off the intake lobes(yes that is .150" missing from a .350" new/proper spec) and it would still make 2750 RPM on take off. However, the peanut can gas filter just ahead of the engine driven fuel pump would get a slight restriction at about 40 hours and you would only get 2600 RPM with an indicated fuel pressure of about 16 psi instead of the normal 20-26 psi at take off power. As soon as it was serviced, we would get 2750 RPM on the take off run.

There was a thread on here a couple of months ago regarding a new lycoming in France with a similar issue that you describe.
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  #15  
Old 06-30-2014, 07:21 PM
Wyo_flyer Wyo_flyer is offline
 
Join Date: Jun 2014
Location: Lyman, Wyoming
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Well I got a couple hours to work on it after work today and I think I found two possible causes.

First: did a nozzle flow test and found one injector nozzle that has a really poor fuel stream. The other 3 nozzles have a clean straight flow. The bad injector flowed about 1/4" more fuel than the other 3 for a 30 second flow test. This tells me that I've had 3 lean cylinders and one rich one. So I'm going to try to find a used nozzle.

Second: fuel filter had some gunk in it and found a possible leak in an -an fuel fitting. It's possible I was sucking air. I cleaned and tightened up all the -an fittings.
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  #16  
Old 06-30-2014, 08:01 PM
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osxuser osxuser is offline
 
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Location: Pasadena CA
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This does sound like exactly what my Carb'd 320 did when the intake lobe started to go on the back to cylinders. Low CHT's and Low power.
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  #17  
Old 06-30-2014, 08:22 PM
RVDan RVDan is offline
 
Join Date: Jun 2012
Location: Frederick, MD
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Assuming a standard nozzle, you can clean the nozzle in Hoppes No 9 gun cleaning fluid and an ultrasonic jewelry cleaner for about 1 hr. If it is dirt this will take care of it. If not the nozzle can be disassembled and checked for obstructions.
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  #18  
Old 07-01-2014, 08:13 AM
Wyo_flyer Wyo_flyer is offline
 
Join Date: Jun 2014
Location: Lyman, Wyoming
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Are the precision airmotive nozzles a direct replacement for factory lycoming nozzles?
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  #19  
Old 07-03-2014, 07:15 PM
Wyo_flyer Wyo_flyer is offline
 
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Well I spent the afternoon tinkering some more and tried cleaning the bad injector again. Soaked it and blew it out with compressed air. Did the flow test again and it's definitely not flowing right. The other three have a nice tight straight stream and this one has a very erratic flow. It is flowing about 1/4" more fuel than the other 3. The 3 good ones flow the exact same amount. I found a used injector that I'm going to try. I'm crossing my fingers that it's really this simple.
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  #20  
Old 07-04-2014, 07:17 AM
RVDan RVDan is offline
 
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Good article on injectors. You can fully disassemble them to clean/ inspect if necessary.

http://www.kellyaerospace.com/articl...lInjection.pdf
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