It's long after midnight and I can't sleep, so an ideal opportunity to do some
uninterrupted email composing. What better than joining in with Bud's
initiative?
Here are a few thoughts:
When I first installed my current and renovated engine, it proved impossible to
get it to run smoothly throughout the rev range, even though the ignition was
working well and the carbs were supposedly balanced with a proper balancer.
Eventually
both were opened and a very rare problem was revealed. One of the sliding
"pistons" had above the diaphragm a spring which had lost much of its
elasticity.
Replacing the springs inside both vacuum chambers completely solved
that problem.
In my experience, if you believe that the carbs aren't balanced, then check that
both throttle arms which have the cables linking them to the throttle lever
are all the way back at their closed positions with the idle screws screwed
fully
out of the way so as not to be touching the arms. If they are moving exactly
together when you start advancing the throttle, then the balance will be nearly
correct and only slight adjustment might be needed. This assumes that there
aren't other problems like air leaks.
A couple of people including a good friend have sent their little black box
ignition
control units (solid state) to an address in the Netherlands to be rebuilt
seemingly with improved electronic components. It cost my friend about 350
---From the UK for both units including delivery etc. He is delighted with the
result,
claiming that his engine feels much smoother. So no need to throw away your
old faulty CDI's.
I would dearly like to see an improvement to the starter sprag clutch to make it
last much longer. I think that an average life for this item in the 912S engine
of around 500 hours and a replacement cost of over 500 not including labour
is a disgrace!
There was a slight weep of oil from two of the cylinder head rocker covers, so
I took out the O-rings and boiled them in water for 15 minutes. After replacing
them the leak was only a little less, so I ordered a new set of O-rings. These
were no better so I wonder what to do next.
A large difference in the "mag" drops was solved by raising the needles in the
carburettors one notch to make the mixture ritcher. Now there is almost no
difference
to be seen, which ties in well with my experience on another large
radial-engined
aircraft having a cockpit mixture control.
Someone else was using waterless coolant and didn't like it, so I've always used
50/50 glycol/water with the higher pressure radiator cap and found no undue
problems with cooling. Having said that, it's a good idea to ensure that the oil
cooler gets the full intended airflow through it and that air can't escape
through poor ducting which would allow it to bypass the cooler.
In my experience excellent propeller balancing can be achieved by balancing the
whole propeller hub/blades/spinner assembly together off the aircraft using a
static balancer.
Off to bed now.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=455941#455941
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