Thorp Air Command - T18.net

Thanks for all the replies!

I ruled out some other suggestions, fuel breather is good, induction system is good, no low compressions, and the mixture position is definitely not a player. The issue is getting worst and now shows up cool and in the Mag check with excessive (but stable) drops, and low static rpm (even when leaned). I'm only seeing ~1900-1950 static full rich were I used to see 2100-2150, and it might bump up to 2000 leaned out. The Mags are being pulled out for the 500 hour which is coming due and because frankly I can't really think of anything else it might be. I'm still scratching my head about why they both seem to be going together and at the same rate. I'll pull the screen too and make sure my cam lopes aren't in there. Fingers crossed. Good news is with the newly overhauled carb its super easy to start...

I swear the Luscombe is getting her revenge for being left out of the KOSH plans this year.

Cheers,

Andy

If the cam and mags check good, the only other thing I can think of is sticky valves. I don't think it would be the cam. The problem would be more consistent (I kinda feel that way about the mags too, unless the timing is drifting).

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Dont rule out plug wires.

_________________
Bob Highley
N711SH
SN 835
KLAL

Any progress?

_________________
Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Yes! Just finished three test flights with overhauled mags, and the surging is gone, and it seems to be making more power. The points were well worn, but more importantly the Mag Guru heated the coils while testing them, and found one side would rapidly degrade when heated. The mixture still needs to be cracked for pattern ops and I think we need to reduce the accelerator pump output since a rapid throttle movement will bog it shortly. But I’m now confident the main issue is resolved, and know the carb, mags, induction, primer, and fuel systems are all top notch! We also discovered a hot mag...

We’ll be at Oshkosh!

Andy

Just don't get no better!

_________________
Bob Highley
N711SH
SN 835
KLAL

That is an awesome picture!