Speaking of priming, my experience with getting a Type 1 VW engine to
prime on a taildragger has been has been pretty miserable! First step
is to coat the oil pump gears at assembly to make a tight enough seal to
hopefully suck oil out of the sump, and that sump tube is pretty long
and large diameter. I also just Lubriplate 105 (Motor Assembly Lube),
mainly because it comes in a large tube with a nozzle on it that makes
it easy to squirt between the gears. Fill the crankcase with oil.
Next step on a taildragger is to get the tail up, preferably over center
so the nose is actually lower than the tail. This is easily done with a
saw horse, and I have a sawhorse with foam and carpet on it that's
custom made for the KR2 (thanks to Jim Hill). By moving it fore and aft
under aft fuselage taper, the angle can be varied. [I threw this in for
Larry F, to get the engineering complication out of the way]. So, best
to have the nose down, but not low enough to kill the prop during rotation.
I then remove the oil pressure sending unit (same location as the stock
oil pressure switch on the Beetle, adjacent to the distributor) and pump
that passage full of oil with an oil can, some plastic tubing, and an
1/8" NPT barbed fitting. This takes a lot more pumping and filling than
you might think. Rotate the prop backwards a little when you think
you've got it full, to see if it will hold more, and refill if necessary.
Remove the NPT fitting and install a mechanical gauge (you can buy a
cheap one for ~$20 at the parts store) so you can watch it and tell when
the engine is primed. Once primed, install plugs, leave the gauge there
(as a second opinion to the whatever electronic gauge you have), and
fire it up, following the break-in procedure.
Contrast this process with the Corvair, which on a taildragger, has the
oil pump at the back of the engine, down low. If the crankcase is
already filled with oil, the oil system is already primed, as the whole
works is submerged in oil! You could fire it up and have oil to the
bearings in a few seconds, but you still need to pump oil through the
system though, to fill any external filter and to pump up the hydraulic
lifters so it'll run quiet immediately on startup.
This is done with an old distributor housing with the drive gear removed
from the end. Insert the old distributor, rotating to engage the tang
in the oil pump gear, put a drill on the top of the distributor (where
the rotor goes) and spin until you hear oil squishing out between the
bearings and other places. Rotate the prop a few degrees, and repeat a
few times. You are now ready to fire the engine up! The old
distributor drive trick doesn't work on the VW though...you'll just tear
the cam gear teeth up instead.
So many advantages to the Corvair...
--
Mark Langford
ML at N56ML.com
http://www.n56ml.com
