Yesterday, the carburetors and intake manifolds were unbolted per the plans and were swung up over the front of the engine. Boxes and foam pads were used to support the parts. Each intake manifold port has a long bolt inboard and a short bolt outboard.
Removing one of the two long manifold bolts on
the right side of the engine … my fingers are pointing to the short manifold
bolts which also require removal.
After all eight intake manifold bolts were
removed, the carburetors/intake manifolds, balance tubes and ignition modules
were carefully lifted off the engine as one large assembly and laid over the
front of the engine. Underneath each intake port is a rubber O ring, so care must
be taken to make sure the O rings stay in their groove … fortunately, all mine
did. It is also necessary to cover the now exposed engine ports with tape or
stuff them with rags. I used blue painters tape … does not stick the best but
will work for this application.
As can be seen in the photo, boxes and foam pads
were used to help support the carburetors/intake manifolds, balance tubes and ignition
modules assembly. Also to help keep track of the parts, the manifold bolts were
screwed back onto the engine so they don’t get lost.
The last items that the instructions have the
builder removing from the engine is the coolant expansion tank along with the four
water hoses running from the expansion tank to the water ports on the engine’s cylinder
heads. Two bolts secure each of the four water ports onto the cylinder heads ... all four need to be removed. Inside each water port is an orange silicone O ring
… it needs to be verified all the O rings remained in position inside the ports.
Removing one of the two bolts that attach the water port
onto the four cylinder heads ... the water port for each of the four cylinder heads requires removal. (The paper towel I wrapped around the
water port turned out to not be necessary … no coolant to leak out of any of the four hoses).
Removing the coolant expansion tank and the four
associated water hose assemblies as one large assembly.
After the water lines were removed and positioning
of the silicone O rings was verified, each water port was covered over
with blue painter’s masking tape to keep debris out of the ports.
The last item mentioned in the plans that
requires manipulation is a bracket for the ignition modules. The plans call for
tracing the positioning of the bracket then loosening the screw enough to
rotate the bracket 180 degrees. I traced the position of the bracket and also
included a tick mark on the aft end of the bracket as can be seen in the following
Prior to loosening the bolt and temporarily rotating
the bracket, the position of the ignition module mounting bracket needs to be
marked on the engine. The position on the engine was marked along with a tick
mark which can be seen in the photo.
The bracket my finger is point to has been
rotated to allow the FF-1207 air shroud to be custom fitted to the Rotax
912 engine. One can see, the top of the engine is now clear of obstructions and
ready for the process of fitting the FF-1207 air shroud.
At this point the engine is supposed to be ready
to begin fitting the FF-1207 cooling shroud. However, had an issue where I could not
get the cooling shroud positioned squarely over the engine to even begin taking measurements
for trimming the air shroud. The culprit appeared to be the lower fuel hose coming
off the fuel pump, it interfered with allowing the air shroud to be positioned
directly over the cylinders on the right side of the engine. After playing
around awhile, I eventually removed the lower fuel line from the fuel pump
which solved the issue. Was planning on removing the fuel line later anyways, because
the DOG Aviation procurement department purchased a Teflon fuel line replacement
kit from Aircraft Specialty. (Rotax has a 5 year MUST REPLACE time limitation
their fuel lines, but the Teflon fuel lines are superior lines and guaranteed for free
replacement for 10 years should they fail in service and only need to be
replaced on condition. Theoretically, they are more or less
lifetime fuel lines). More about the
Aircraft Specialty lines will be covered in subsequent postings.
The lower fuel line my finger is pointing to is
preventing the air shroud from dropping squarely onto the engine … so it was
removed from the fuel pump which allowed fitting of the FF-1207 air shroud to
I can see it now … this will be a long process
with lots of on and off cycles required to achieve a tight fit. I was able to
get the shroud to begin slipping over the cylinders but it will require much
more trimming before the fit is completed.