[K3PZN-List] Generator Update/valves/electic drill start

[Frank Rodski]

Rob
When I was just a kid, my father was building our new house and borrowed
from a friend, a large concrete mixer run by gasoline engine. It was larger
than the portable ones you see these days and was intended for large
construction projects.  It was a 2 cycle engine (I didn't know that at the
time) as it had an external oil tank and used it quite rapidly. If the oil
would run out because nobody was watching it, the engine would die (probably
from overheating) and then would be a bear to start (worse if the thing was
full of half mixed concrete). I think that is where I learned my first cuss
words. In any event, that mixer was a bear or maybe a bronco to start most
of the time as I recall and bucked and kicked back upon cranking. Even
though it had a crank designed to turn one way and disengage when the engine
started, it was known to have kicked back one day and broke a fellows arm.
Another time it stayed on the shaft spinning a high rate until it was thrown
off. As far as I remember, everyone was under cover, but a nearby car had
some severe damage.  The reason I am telling this story is to dissuade Rob
or anyone from trying to start it with a drill or anything that you would
have to hold onto except for the original crank and that should be inspected
for wear or damage each time it is used.

Although I have not lapped any automobile engine valves, I have done several
small engines using a tool that is driven by a drill and some lapping
compound ( I think it is called) years ago. The valve seats had some fine
pitting on a couple of them, but they came out ok. I don't have any tools
like that now.

Frank  K3MTT



-----Original Message-----
From: k3pzn-list-bounces at mailman.qth.net
[mailto:k3pzn-list-bounces at mailman.qth.net]On Behalf Of Heath, Rob
Sent: Wednesday, July 07, 2004 9:02 AM
To: Carroll County Amateur Radio Club
Subject: RE: [K3PZN-List] Generator Update


Thanks to everyone for the replies.  If we still have a spare around, that
would a nice source for parts if we need them.  If it is still in the
original box, maybe it has some service manuals as well.  For now, I think
tuning up the existing generator would be easier than swapping and trying to
get the other one running.  I found a number of things that need to be
worked on, but most of them are pretty minor.

The trickiest job is going to be lapping the valves.  I don't think we have
a problem with ware.  I think we probably just have a little rust and
pitting resulting from the valve sitting open for long periods of time.  We
could have an issue with the unleaded gas, but since the other cylinders are
in great shape I am thinking it might just be some pitting.  A lead
substitute is a good idea.  Hopefully we have not put enough hours on the
engine to do any harm yet.  Given the layout of the heads, a valve job
doesn't even look that difficult providing I can find a replacement head
gasket. Even without a valve job, cylinder 3 still has compression.  Since
the engine only runs at 1,800 rpm we may not need to worry about high
performance.

As far as the starter is concerned, I am steering clear of that project.
Fabricating a starter is beyond my skills.  If the Vo-Tech can do it, I will
leave it to them.  A traditional starter setup would require a new flywheel
with gears.  The existing flywheel is used for the magneto and as part of
the cooling system.  Its size and weight may also be required to maintain
steady rpms.  Swapping it out is probably not a simple task.  As a
compromise for now, I am thinking of trying a pinned shaft on the end of a
half-inch drill.  It is certainly not the ideal solution, but would be
better than cranking if it works.  There is some irony in using an electric
device to start the generator.  However, as far as I can tell the generator
is usually only started at the FTC and the field day site where small
generators are available to help start the big one.  This still leaves the
hand crank available if we need to use it.  With a good tune up and regular
exercise hand cranking may not be as difficult as is has been.

Rob







-----------------------------------------------------
BREAK -----------------------------------------------
Next CCARC meeting Monday July 12, 7:30 PM, at the FTC.
Our guest speaker is Bruce Carpenter, ++ Grounding Techniques in the Ham
Shack. ++
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