stunthanger.com
Engine basics => Engine set up tips => Topic started by: Norvaldo on April 29, 2007, 01:42:53 PM
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Hi.
I have a PA .61 SE which i am running muffled with pressure.
I remember that Randy sent me some extra head shims which i mounted.
That was last year.
When checking today, i found that there was a total of 4 (four) of the brass head shims plus the one fixed to the head.
This really sounds a bit much to me. I fly at sea level using 10% Nitro and 20% oil (75/25 synth/castor).
Maybe Randy have some ideas.
Norvald
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Hi Norvald,
Is there a problem with the way it runs now? If so, please describe it.
The extra head shilms are always provided, as far as I know, in case you need to tune it to more nitro, soften the break, etc.. I do not know how many are in ours, but I just ask Randy if something is wrong with the way they are running (which ain't often!)
Bill <><
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No..There is nothing wrong with the way it is running.
(My flying today ended with the engine not being able to get into 4 cycle at all, but that was explainable. A fragment from the fuel tube had got stuck in the needle valve. I must have used some wrong tool when i cut it.)
However: I am the only one having this engine here in Norway, so i cannot judge exactly if it is running optimal.
I.m.o , even a not optimal PA .61 performs better than most others.
I just thought that 5 head shims sounds to be a lot..
Norvald
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Hi.
I have a PA .61 SE which i am running muffled with pressure.
I remember that Randy sent me some extra head shims which i mounted.
That was last year.
When checking today, i found that there was a total of 4 (four) of the brass head shims plus the one fixed to the head.
This really sounds a bit much to me. I fly at sea level using 10% Nitro and 20% oil (75/25 synth/castor).
Maybe Randy have some ideas.
Norvald
Hello Norvald
The PA 61 side ex engines normally run with .020 to.028 thou head shims. It doesn't matter how many shims are there, the TOTAL of the shims are what counts, You may have several .003 thou shims in your engine.. or a .005 or .008
And there is no shim that is fixed to my heads, it just may be stuck, you should be able to remove it easy.
If the motor seems to need a little more punch in the manouvers, take out 1 shim, if it is a little too strong in the manouvers add 1 head shim, You can also "tune " the engine by adding or taking w\away nitro...IE: run 5% if 10 is making the engine come on too strong, or run 10% is 5% is just a little too tame or weak. any questions you have please just ask
Randyaero@msn.com
Regards
Randy
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Hi Randy.
That was just what i was after..
You were right; it was not fixed, it was just a little bit stuck.
Tomorrow is holiday here in Norway and wether is perfect so i will spend the day flying.
Plenty of time for testing with 3 ,4 5 shims..
I will bring both 5% and 10% fuel with me.
Norvald