On Sat, 16 Aug 2008 23:54:16 GMT, "Dick" wrote:

The specs for my C-85 are upper plugs mag @ 28* BTDC and lower @ 30*BTDC.

My results are upper @ 30* BTDC and lower @ 32* BTDC.

I couldn't find a "flower pot" with attached degree wheel to borrow and
attach to the prop hub so used a little "mickey mouse" circular protractor
with a free swinging needle/pointer.

Two separate readings confirmed my 30-32. TDC was identified and impulses
unloaded before taking the readings.

My question is whether my results are acceptable for a low speed ,
experimental or need to be readjusted??

If need to be redone, I'd appreciate a little on why, please.


not sure of the C-85 but on the O-200 there are cylinders out there
made before a subtle design change was implemented that have a history
of departing the engine on engines with advanced timing.
my own engine has four of those early cylinders and so runs with
timing a little retarded from what it could be. (as per the AD)
if it need be done that may be why.

Stealth Pilot