Conference vmszoo::rc

    A friend of mine just built a _beutiful_ Super Aero_Master from
    Great Planes(?).  Its his first model and it is absoutly perfect...
    except for one thing.  He neglected to provide any place for the
    cooling air to exit the cowling.  The logical way to do this it
    seems would be to cut out the four arcs behind the cowling where the
    round cowling meets the square airframe.  Does anyone have any idea
    if this will provide sufficient air flow?
    
    Jeff Gilbert

    Jeff,
    
    I believe that the "four arcs behind the cowling" is all the cooling
    air exit area the mfgr. intended and it should be adequate.  My
    Bucker Jungmeister (from which Andrews borrowed heavily when designing
    the Aero Master back about '66) has the same setup you describe;
    the front of the radial cowl is wide open with exiting only through
    the gap(s) at the rear of the cowl formed by a round cowl mating
    with a squarish fuse cross section.  I've never experienced any
    heating problems in over 400 flights with this arrangement.
    
    BTW, Jeff, please tell yer' friend that the Aero Master is definitely
    NOT a trainer; the 'Aero-Monster' has humbled a good many experienced
    pilots when they first layed hands on it and a beginner has less
    than no chance whatever learning with it except in the hands of
    the MOST experienced instructor available and the most closely
    supervised training program possible.  My advise would be for yer'
    friend to put his "_beautiful_ Super Aero_Master" away and save it 
    'til he has at least a trainer and an intermediate sport model under
    his belt.  Otherwise, the odds are greatly against him and he'll
    very likely lose his pretty ship.   

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    Thanks for the advice, I'll pass it along to him.
    He had it at the field the other day just to let one of the experts
    show him that this thing he has been working on for so long really
    does fly.  He is planning on getting an inexpensive ARF for training.
    
    Jeff

        Re:< Note 289.6 by FSTRCK::GILBERT >

                I hope  your friend heeds Al's advice.  I am on my second
        Aeromaster.  The  first  one  ended  up a mess of epoxy and balsa
        because of innumerable stalls on takeoff and landing.
        
                      _ 
                     / |
        |  _====____/==|
        |-/____________|
        |    |        o \
             O           \ 
                          O
         Hang in there! o_|_
                          |
             Anker      \_|_/

    I opened the cowl on my Aeromaster behind the engine head (side mounted
    OS91 Surpass).  That was necessary to get the cowl over the motor
    anyway and it seems to provide plenty of cooling.  I did not open the
    rear of the cowl at all.  What I ended up with is a slot that goes from
    the engine head front all the way to the rear of the cowl, including
    the back plate.  This slot is the width of the engine head plus some
    for clearence.  The OS 91 sticks a fair ways out of the cowl anyway so
    the top of the head is actually cooled by air flowing over the outside
    of the cowl.
    	I strongly support Al's and Anker's advice to save the Aeromaster
    until your friend has plenty of experience.  It is a great flyer but it
    requires more skill than any beginner I have seen to fly it.
    
    Charlie
    

    I have a question and thought this may be the right place to ask
    as aposed to starting another note. I recently discovered the electric
    eindecker I was building will not accept all the gear I have to put in
    and Im in no possision to purchase a new radio and batteries. My 
    question consernes the cox queen bee (.074). does anyone own or has any
    one heard anything about this engine? I will more than likely strap
    one of these engines to the bird.
    
                                                 Thanks, Jim

I have heard of the queen bee. Its a nice little engine and depending
on the size of your electric it may or may not be able to drive it. It
will surprise many of you the power/speed that can be acheived with
the smaller COX engines. Tower Hobbie has it listed if you want to
read some specifics on it. A power pod and or tank mount is available.

Hope this helps

Ken

    The plane that it will power is the davey systems eindecker. It's
    designed to use either the provided motor (540 type) or .049 so
    Im pretty comfortable that the .074 will be plenty. Thanks for the
    reply.
                                          Jim

  Tom,

  I'll try to remember to measure it tonight.


      Jim

    Thank's Jim.
    
    Also if possible? Please measure the O.D. of thecarb barrel that
    fits into the engine casting? If possibel I'd like to substitute
    the OS carb instead of using the ASP carb.
    
    Tom

    Can anyone tell me the difference between an OS61 FSR (Rear Exhaust)
    and an OS 61VF?
    
    
    I bought a new OS61 VF at the NCRCC auction yesterday thinking it
    was a rear exhaust FSR. Older style case with bolt on front housing.
    Not a long stroke.
    
    
    Tom

Tom,

I think you will find all FSR are front intake side exhaust, VF's are front 
intake rear exhaust. All the 61VF's had a bolt on front housing, it is only 
recently OS have acknowledged the problems of bolt on front housing and started 
building more engines with the one piece case.

See note 389.5 for more detail.

John

    
    I seem to remember seeing an ad for an exhaust adapter (extender?).
    I need to move the muffler for an OS .40 away from the engine a
    quarter-inch or so.  Wanted to find out if something was available
    before drawing up a print to have my dad hack one out on his Bridgeport.
    Sorry for my laziness, I haven't even checked the Tower catalog
    yet but will do so tonight.
    
    Bill

I received a new OS .40 FP from Tower last nite.  They have been
advertising that the .40 FP is now supplied with an ABC liner.
When I got the box, I couldn't find any markings that showed it
to be indeed ABC, in fact, everything enclosed with the box was
apparently several years old.

I called Tower on this and the Cust Svc. person said to check the
box for the number 13331, which designates the ABC engine.  Sure
enough, there it was attached to a little gold seal.  Please
note, this is the only way that you can be sure you're getting
the new engine, it is not marked in any other way.

Its sure a nice looking engine.  I enjoyed turning it over in my
hand and feeling the crisp edges of machined metal.  A real
jewel.  Maybe it'll even run.

I know that ABC means that the cylinder wall is chromed,
something learned from Porsche no doubt (they pioneered the
process of chroming aluminum cylinder walls).  What is the
advantage of this, besides the "more power and longer life" from
the magazine ads.

    John,
    
    Perhaps the easiest way to distinguish an ABC engine is to simply look
    into the exhaust port and determine whether or not the piston is
    ringed.  If it is, it is NOT an ABC engine...ABC's all use a lapped
    aluminum piston with no ring.
    
    ABC means Aluminum-Brass-Chrome.  They make the cylinder liner from
    brass, then chrome-plate it and run a lapped aluminum piston in it. 
    The idea is that these metals have temperature coefficients which allow
    them to expand/contract at an equal rate.  Therefore, as the engine
    gets hotter and the piston expands, the cylinder expands equally,
    preserving the compressionand, more importantly, preventing the engine
    from siezing up.  This provides a constant power output over a very
    wide operating temperature range making the engine less sensitive to
    too-lean/overheat type situations.
    
    The ABC is a bit fussier to break-in properly but, once done, handles
    as easily as a ringed engine and will outlast it infinitely.     

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    
    In my experience ABC's are also more prone to damage due to 
    contamination,dust,sand etc. 
    
    For an airplane I prefer an ABC engine for the added power.
    
    For a chopper I prefer ringed for the decreased possibility
    of dust damage.
    
    
    Each engine/type has it's advantages dependent of what conditions
    it will be operation under.
    
    
    Tom
    

Thanks Gents.  It would be nice to spot the ABC if the old FP had
a ring, but it didn't to my knowledge.  The piston seems to shine
more than any other engine I've seen, though you've said the
chrome was on the cylinder walls.  Any other way to tell them
apart?

The PT40 is coming along great -- glancing at the TV guide, it
appears to be another great week for model airplanes.  Two more
weeks to rollout!

    Re: .-1, John,
    
    The only way I know to tell for sure whether an engine is an ABC is,
    first determine that it has a ringless piston.  If the piston has a
    ring, go no further, it is NOT an ABC.  OK, assuming you have a
    ringless (lapped) piston, you pull the head and look at the cylinder
    liner.  You may be able to slip the liner up enough to tell or you may
    be able to tell by looking at the inside of the ports...what you're
    looking for is whether the liner is made of brass or cast-iron.  If you
    can determine that the liner is chrome-plated brass (it should only be
    plated on the inside), then you have an ABC engine.  A cast-iron
    sleeve/liner = non-ABC.
    
    BTW, as Tom says, an ABC engine, or any lapped-piston engine for that
    matter, is more susceptible to wear/damage from dirt/dust/foreign
    objects than a ringed engine.  However, the ABC engine delivers
    dramatically increased power and longevity over the ringed variety.
    The difference in the flight characteristics of my overweight ol'
    Yeller' Peril after replacing the ringed O.S. .61FSR with an O.S.
    .61FSR-ABC was almost like upgrading from a .60 to a .90!  Performance
    went from just marginal to completely acceptable, almost sparkling.   

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

Why is it my fate to ask so many questions in this note (a
rhetorical question)?  I don't want to know about engines.  I
want to put the glow and starter to it have the lousy thing start
and go fly -- I want to be totally ignorant of the subject --
Why, Oh Why?

Ok. So much for John's lament.  Over the years I've managed
to ding up the stupid cross-point screws on two engines: a
Thunder Tiger .15 and my old reliable OS .25.  Nothing wrong with
the screws, you just can't get a driver on them to tighten them
up properly.  Should be simple enough to fix, just go to the
model junkie and buy new ones, right?  Wrong!  Nothing is ever
that simple when it comes to me and engines.

I noted that the same screw is used in both engines, so I took
the TT crankcase and a sample screw to Jack's and went through
his collection.  I tried 2.5mm x 8,10,and 15 pitch.  Also 3mm by
the same pitch.  All screws jammed after a few turns.  Jack
commented that he could order a screw kit from OS for the .25
@$3.80, but it was for the new .25 and mine is early '80s
vintage.   Knowing my luck I figured that they probably changed
the thread and I'd be out a few bucks so I decided to play a
couple of other cards

Went to the machine shop in CXO1 and managed to get the
supervisor's attention.  He spent about a half hour fooling with
it and came to the following conclusions: its a 3mm diameter and
between 5 and 7 pitch.  He recommended drilling it out and
cutting a 6-44 thread.  He also commented that it could be
anything, since in the metric world there are no standards like
our National Coarse/Fine series.  Each country, and even each
industry could have its own diameter and pitch standards...great
huh?

So for my next card, I went to a car hobby shop.  Checked their
3x6mm screws along with 2.6xsomething, no luck.  Then I called a
specialist metric store in Denver.  He said it was probably 3.5x6
since that's what is used in many engines.  I question this for
my case, since the 3mm measurement that the machineist (sp?) made
was dead on.  He had 4 screws -- at a buck apiece!

Anybody know what the mystery screw is?  We even checked out some
oddball American types like the 5/44 used in guns...no luck.
My next hope is to cut some new screw slots, a job that I can
easily do with my clockmaking tools.  But I'd rather put in new
screws if I can find out what they are.

    You say you tried 2,5 mm x 8, 10 & 15 pitch.  I'm looking in the
    Machinist's Handbook, 23rd Edition and for a diameter of 2,5 mm,
    the pitch is more like 0,45; for 3 mm it's 0,5 and for 3,5 mm it's
    0,6. (see page 1526, Table 3) This is coarse pitch metric M profile
    series (ANSI B1.1M-1983).  Fine pitch doesn't start until 8 mm dia.
    The highest pitch there is 3 mm and that is for 200 mm diameter.
    Threads produced under the listed ANSI std are fully interchangeable
    with threads conforming to other National Standards which are based
    on ISO 68 (an International metric std) basic profile.
    
    You might also have a British Standard ISO Metric thread (BS 3643:Part
    1:1981).  But then, they list 3,0 x 0,5 and 3,0 x 0,35 for the coarse
    and fine pitches respectively (same book, p 1598, Table 6).
    
    Did your machinist use a thread gage on the thread to determine
    the pitch?  If they have an optical comparator, you can make direct
    measurements from crest to crest on the threads quite accurately
    to get the pitch.  I find it hard to believe that the pitch could be
    5 threads/mm since the threads would only be .007" from crest to
    crest.  The standard distance for 0,5 pitch (that's 0,5 mm per thread)
    is 0.0196" crest-to-crest.
    
    Other than the above, I can't offer much more in the way of help.

    
    Bruce Bretschneider

Ok. Thanks Bruce.  The machine-fellow tried a pitch gauge on it
but did not have one that fit -- he used the gauge to determine
that it is between 5 and 7 but did not have the 6 gauge.  Based
on the fits I tried with the car screws, I don't think its 6.

Gonna have to read your reply several times more to figure out
what I should do next.  Interesting about the British thread, I
didn't even think of that, but in bicycles it is the British
standard that the Orient uses, so maybe its so with engines --
anybody have comment on that?

I have a Supertigre .15 that I'll check the threads on also, just
for drill. 

John,

I have not done much  with small (< 40's) engines but I have found UNC and UNF 
threads  are the rule in most OS applications.


John

>>  I tried 2.5mm x 8,10,and 15 pitch.  Also 3mm by the same pitch.  

    John, your terminology is unclear to me.  2.5-8 ????

    US standards specify threads per inch.  
    	As in  3-48, 3-56, 4-40, 4-48, 5-40, 5-44, 6-32, 6-40
    Metric standards are in mm per thread.
    	As in  2.5-.45, 2.6-.45, 3-.5, 3-.35, 3.5-.6, 3.5-.35

>>  its a 3mm diameter and between 5 and 7 pitch.  
    He recommended drilling it out and cutting a 6-44 thread.  

    It looks like you dropped a decimal point.  A metric screw with 
    0.60 mm/t corresponds to 42.33 tpi --- close to 44 tpi.  [FWIW, 
    2.6-.45 = .1024-56.44,  3.0-.5 = .1181-50.80,  3.5-.6 = .1378-42.33 ]

>>  3x6mm ... no luck.  

    3-0.60 would have been my guess from the machinist's measurements.
    He may have made an error.  Is the screw less than or more than an
    1/8th inch in diameter?  You can check that at home.  If you have a 
    drill gage for numbered drills, will the screw fail to enter the #30 
    ( 0.128 inch ) hole?  A 3mm screw should enter the #31 hole.

    The screw that holds the 4D carb on my OS MAX 40SF measures 
    0.1327 inches in diameter; allowing 0.005 for clearance, that's
    a 3.5 mm screw.  The threads are hard for me to measure accurately, 
    but they seem to be between 40 and 45 tpi --- that would be 0.6 mm/t.
    So I conclude that the screw is a 3.5-.6

Suggestions:  

    Try the screw that holds a Toyota windshield wiper blade on the arm.

    Or find a UNF 6-40 screw and try that.  (Hard to find as a screw with 
    a head; easy to find as a set screw to test the threads.)  The 6 gauge
    screw is 3.5 mm minus clearance in diameter.  40 tpi for a short depth 
    should fit a 42.33 tpi hole.  So the UNF 6-40 is near a 3.5-.6

Alton, who shouldn't be screwing around at this hour.

Al and others:  Thanks for the advice.  To be honest, I think I
messed up the terminology by calling the second number in the
thread designation "pitch".  I was hoping to get away with it but
it doesn't look like I'm gonna so I'll own up to it: until the
last few messages I hadn't the faintest idea what the second
number stands for.  Figured I could snow job around that one, but
I got caught.  In fact, I'm finding out that I don't know
the first thing about threads (along with a bunch of other Bozos
out here in computerland)!

And while we're having confession time, I also don't remember
exactly which metric screws on the rack I tried -- I just know
that they were all the common ones (DU-BRO?) and none fit.

So fer sure its not 3x5, 8,or 12, and its not 2.6 or 2.7 by
anything.  Its also clearly not an American standard thread of
any gauge because the machine-feller eliminated everything
American, and because he measured the diameter as dead-on at 3mm.
Also, I put my American thread gauge on it and didn't even come
close to a fit.  We don't have one of those microscopes that I
know of.

I'll try that drill slip trick (though he did that too and came
up with a number I don't remember) and report back on it. I
really suspect that its the British thread, and I am planning to
take the engine back down to the machine shop show the
machine-feller the last replies and ask for a translation into
Neanderthal.  Probably be Friday.

Well, I finally got an ID on the screw thread: its a 3 x 0.6 x
9.5 metric thread.

Part of the confusion I had came because I didn't understand how
the threads were designated.  The first number is the diameter of
the screw, the second is the pitch, and the third number is the
length of the screw.  When the earlier replies mentioned 3 x 0.6,
for instance, I thought that what they really meant was 3 x 6.0,
which is what I had already tried from the Du-Bro rack.

No, there is a difference between 0.6 and 6.0, and the Du-Bro
screws were labeled with the diameter and length only, not the
pitch, theirs being the standard metric pitch of 0.5.  That is
why the whole rack of screws wouldn't fit, they were all of the
same wrong pitch!

As I mentioned in an earlier note, the 0.6 pitch screws that I
located in Denver were a buck a pop, they had only 4, and the
person there said that model engines were virtually the only use
of the screws.  I'm going to try to find another source, and
failing that, I'll file the screw heads with a slot.

    If possible, replace the screws with cap screws.  Most of the 40 and up
    engines come with cap screws instead of Philips and they are much
    easier to keep serviceable.  I think you can buy OS screws from Tower.
    
    Charlie
    

    I tried to tell you that the pitch couldn't be 6.0 a way back when.
    Pitch is the number of millimeters a nut would advance in one
    revolution.  A pitch of 6 would make it too easy for the nut to back
    off.  Glad you finally got it straightened out.

I came across something last nite that I've gotta pass on.  I had
pulled the OS .40 out of the PT so I can bench run it to find a
persistent trouble and had installed a new Fox .36. Runs great by
the way, but they all run great at first.

I've been doing a lot of head scratching lately trying to figure
out why *all* my engines have given me so much trouble.  So there
I was installing the tank and grumbling to myself about how
impossible it is to install the tank with the carb fuel inlet
near the middle line of the tank...when I hit on a brilliant
idea.

I have been installing the tanks so the fuel and pressure lines
coming out of the tank were a the TOP of the stopper...why not
rotate the stopper 180 degrees and put the lines at the BOTTOM of
the stopper??  That's what I did, and you know what -- I knocked
off between 1/4 and 3/8 inch of height from the fuel line!  Its
now a nice straight shot from the output line of the tank to the
carb inlet.  Haven't checked it yet, but this could be
significant at this altitude, especially with the smaller engines
like my infamous K&B.

Now guys, I never professed to be a rocket scientist, but in 3
years of fooling around and frustration, you'd think that even I
would have thought of this already.  Of course, I can point out
in defense that none of the gurus at the field picked up on this
one either!

It occurs to me that maybe others have made this mistake too,
though I don't expect anyone to admit it.

    I just bought me a(nother) OS 61 LS pumper, and along with it was a
    flyer from Tower, advertising heli-chomper engines for approx. 1/2
    price. All items are brand new, but perhaps being discontinued, since
    they are not listed in their latest catalog/Tower talk. I post the
    stock #s fyi, in case someone want's to order.
    
    Stock# Description                                Cat Price Flyer Price
    ====== ===========                                ========= ===========
    WR2212 OS 61 RF-H LS Heli Rear Exhaust            $184.95    $109.99
    WR2213 OS 61 RF-H-P LS Heli w/Pump                $222.95    $129.99
    WR2214 OS 61 RF-HS RX w/cone                      $194.95    $129.99
    WR2215 OS 21 VF-BR ABC RC engine                  $124.95    $ 79.99
    
    My question is, can Heli-chomper engines be used for fixed wing a/c?
    The funny looking square head could be taken off and turned on a lathe
    so it looks less outlandish, but is not necessary. Also, the rear
    exhaust means ya gotta used a toooned pipe or can a chomper muffler be
    used?
    
    Is it worth getting any of these, given that I can get 2 of these for
    the price of my OS SF 61 ABC pumper? Or am I going to have a lot of
    headaches? I could reserve it for a future project if I hear it is
    worth my time and $$.
    
    Besides, some others (heli pilots) might be interested in gettng 'em
    for 'emselves.
    
    ajai

RE:289.44
Hi Ajai,
As you surmise, the square head doesn't matter and can be cut off if you want 
to. Another possibility is to buy a normal aircraft head that OS sell just for
the purpose of converting the engine for fixed wing use. As for the rear 
exhaust, I know of a muffler or two for use with rear exhaust engines on 
copters  but they probably wouldn't work out too well on an airplane. Because
of the position the engines are put in on most helicopters, rear-exhaust is 
really a mis-nomer. The exhaust is actuaslly coming out the bottom. For your
application I think you'd probably be forced to use a pipe.

                                                        /     \ /
Dan Eaton - Demented                                   /      / \ 
            Dragonfly                                 /       #  
            Pilot                                    /        #
                                                    /        #
                                                   \       # 
                                                  //@@@ #
                                                 / l @##  .  
                                                /   #@   .
                                               /        .
                           @                  /       \.
                          _/\
                            /\_
                            l 
                                                       
  

    I personally would recommend to use a muffeled tuned pipe anyway. It's
    much quieter, much more effective and with a rear exhaust you can hide
    the pipe inside the fuse what gives you a better looking and better
    aerodynamics. Since Ajai has flown that much this year how's about
    a pattern airplane as the next project ?  And an OS 60 LS Rear Exhaust 
    for just $110.-  .....hmmmmm, there's just one thing on my X-mas wish
    list . 
                      \\
                       \ \                    __
                        \  \                  \ \
                         \  \                  \ \
                          \  \                / \_\
                           \  \              /LO |
		       .o^^^--------==========___/
		      <      \  \-''
		       '-___-'\  \            
			       \  \
                                \  \          Holm- und Rippenbruch,
                                 \ \
                                  \\                          Bernd

    Chad, there are a large number of notes on this subject that you might
    not have yet read, so I have write-locked this topic to avoid having
    all of of this information repeated needlessly.  If you cannot find
    help in the notes suggested below, get back to me and I'll unlock this
    [and move your entry to a more appropriate place].  The bottom line
    intent is to help you, not to impede the solution.

    Keywords, ENGINE_TUNING, ENGINE_HELP_NEEDED, and ENGINE, would lead you
    to directory notes 11.532, 11.181, and 11.595, and those directories
    would lead you to the following:

 Topic  Author               Date         Repl  Title
--------------------------------------------------------------------------------
    65  RIPPER::CHADD        22-FEB-1987    89  Engine Tuning
   149    GOLD::GALLANT      30-MAR-1987    11  carburetor adjustments
   167   PYONS::TAVARES      18-MAY-1987     9  OS Problem
   191  DPDMAI::GREER         7-APR-1987     2  INFLIGHT MIXTURE ????
   314  SPKALI::THOMAS       16-SEP-1987     5  LEAN ENGINES??
   194  MJOVAX::BENSON       14-JUN-1987     4  Have TT.15 - Need Help !!!
   264  RUTLND::JONEILL      13-AUG-1987    22  engine problems [and helpful replies]
    93  BZERKR::DUFRESNE     18-MAR-1987   164  Engine wizards wanted
   289  RIPPER::CHADD        27-AUG-1987    46  General Engine info.
   436  TARKIN::HARTWELL     19-JAN-1988    43  Engine question

    Since the problem source might be in the fuel system, not the engine,
    please read 309.24 (which I will now keyword with ENGINE_HELP_NEEDED). 

    
    
    I need some information froma fellow noter.  ANyone with on OS 70 or
    90 four stroker please help..  I need to know the length of these
    two engines from the prop thrust washer to the back end of the carb.
    This is the overall length including the carb.
    
    
    Thank's
    
    Also if possible... OS usually has a side view (full sized) included
    in the box for the engine.  If anyone could make a copy and send it
    to me I'd appreciate it.
    
    
    

    
       I have both engines. I will try to remember to measure them both
    tonight. as far as side views go, I will check to see if I have the
    diagram to copy.
    
                                                    Dan W.

    Thank's Dan...
    
    I'm not sure what engine I'll be installing in my scale projects, hence
    the need for both engine's measurements.
    
    
    Tom

    A couple of comments on an engine 'problem' that I had.
    
    I recently got around to re-assembling my heli kit with the intention
    of actually working on finding out how to fly the thing.  It was
    suggested that, being a complete novice, I should run the engine in
    fitted to the model (since it would spend most of its time on or near
    the ground, not using a great deal of throttle or revs).
    
    Anyway, I turned up at the club flying field a week ago and asked
    someone to try and get the thing started (note that the engine had
    never been run, and has been untouched for nearly a year).  With
    endless amounts of playing with the needle setting, blocking the
    exhaust to pump fuel through, different glow plugs and so on, there
    was absolutely no sign of life.  Suggestion was that perhaps I
    should take the engine out and try to bench run it.
    
    Rather than go to that trouble straightaway, I thought I'd give it
    another try the following week.  With this in mind, I made sure that
    my heavy-duty battery (for my Jeep) was fully charged up beforehand.
    I had a guess that *maybe* the fuel was a problem, since that was
    also about a year old and was not changed the previous week, so I
    bought some more fuel from the local model shop.
    
    So, this week, I turned up at the site and proceeded to connect up
    the starter panel leads and so on, fueled up (with the new fuel),
    connected the starter, hooked up the belt and tried it.
    
    Surprise, surprise, after a few adjustments to the needle, I got
    the engine to fire up.  This was a breakthrough, since there was
    no evidence of live the week before.  When I disconnected the glow
    plug lead, the engine shortly fizzled out.  At that point, I called
    over someone experienced to try and get the correct needle setting.
    Within a short while, we had the engine running quite happily,
    slightly rich since it was yet to be run in.
    
    A while later, trying to restart the engine proved to be unsuccessful
    for a while.  Rather than get disheartened, I looked over things and
    realised that their were a few bubbles in the fuel feed.  Rather than
    force these through by pressurizing the tank with lung power, the
    simple method of blocking the exhaust whilst turning the engine over
    with the starter cleared these.  Then, on with the plug connector,
    turn it over again and it started.
    
    Any comments from you experienced noters as to whether the old fuel
    was likely to have been the problem ?  Any other comments on trying to
    start engines that don't want to know ?
    
    J.R.

    I picked up a used HP .25 at an auction last year and installed it in
    my Gremlin.  I managed to get it running yesterday, but clearly this
    engine needs some work and possibly some relpacement parts.
    
    Does anyone know if HP has a repair/service center where I could send
    this, or order parts from?
               
    Thanks,
    Joe

    re: -.1
    
    That should be HB .25.  I erroneously wrote HP which I understand is
    also an engine company.  It gets a bit confusing when you are
    dealing with two companies with initials that are so similar.
    
    
    Regards,
    Joe

    
    Hello Joe,
    
    if you tell me REAL quick what you need I could try and get it before
    I come over (to US that is). There should still be enough parts around
    here for the HB25. I have one, too. Other than that, HB is not in
    business anymore.
    
    Bernd

    Hi Bernd:
    
    Thanks for the offer.  Yesterday I made contact with a company in
    California with a three-letter name something like JKL or something
    like that (probably the guy's initials), who said they have purchased
    all remaining stock of parts from the now-defunct HB Company.  They can
    repair engines, and they sell spare parts.  I asked for a catalog and
    they are sending one.
    
    I talked to them about the carb, which I suspect has some problems. 
    WHen I described it to the guy on the phone, he said, "that doesn't
    sound like an HB carb", and then went on to ask me if it was a Perry
    carb.  Apperently, most HB engines ended up with Perry carbs, but mine
    clearly has something else.  That alone could be the problem, but I'm
    not sure yet.
    
    At any rate, after flying last night and having all kinds of problems
    with the HB25, I went home and tore it down.  Real dirty and some rust
    inside.  The two ball bearings were filled with grit, and I tried as
    best I could to clean them out.  I found that the carb barrel that fits
    into the body was actually too large in diameter to seat all the way
    into the opening. I "adjusted" it carefully using a file until it fit
    properly, put on a new O ring, and reinstalled it.  After cleaning and
    oiling, and reassembly, it had more compression, turned over much more
    crisply, and felt like a new engine.  Tonight I will ring 'er out and
    see if I have accomplished any improvements in performance.
    
    But to answer your question, the immediate need I have is for gaskets
    for the surface between the crank case and the shaft housing, and also
    the muffler.  If you can find these I would be appreciative.
    
    Thanks again,
    Joe