Re: Thunder Tiger Pro .46

On Mon, 26 Jun 2006 01:57:17 GMT, "Solo 001" <nleb10@xxxxxxxxxxx>
wrote:

Is it common for the thunder tiger pro .46 to run very hot even when running
very rich up to the point that it stall and almost feel like it jam at top
dead center? This is a new engine with only two full tank run through it on
test bench. Put it in the plane started really nice was practicing taxing a
few time up and down runaway stop refuel restarted and went to full
throttled and it started to bog down so I went to lean it a bit and before I
could it quit and it was very hard to turn pass TDC.
Any one out there that might have and explanation?

Thanks.

Did you buy this engine new or used ?

Without actually seeing what is happening , my guess is that you're
running it TOO rich. That's an ABN engine ( aluminum ,brass nickel)
with a tapered liner. If the engine doesn't get hot enough to
expand the liner at the top , then there is not enough clearance and
the piston 'drags' at the top. Can you feel the drag at the top when
you turn the engine over cold ? That will tell you that something has
to happen to free that engine up so it will run like it should , and
that something is heat.

All ABC , ABN and similiar engines will be very stiff at the top ,
sometimes almost to the point they feel 'locked up'

You can ......RUIN....... an ABN or ABC type engine by running too
rich. The first few minutes are the most critical.
It's got to expand enough enough at the top to allow the piston to
pass through that tight spot. If it doesn't get hot enough to expand,
then the piston is forced through the tight spot and will wear
it excessively. This also puts undue stess on the crank pin and could
possibly bend or break a con rod. Then the engine heats , when the
engine is too hot it also changes the timing , it will fire sooner and
further add to the heat problem.

With all this drag going on you can see why the engine will run hot
even sloppy rich.
Of course , you should always feel a little pinch at the top when the
engines cold , just shouldn't feel like it's locked up.

Also , make sure you're running the correct prop for that engine.
Actually , a smaller prop is better during break in. That allows the
engine to turn up better and and also remain cool.
Just go down 1" in diameter or pitch and that will be fine.
I think that engine in most aps will run a 11x6 , so a 10x6
or 11x5 will be fine for break in.
High RPM is very important to the break so we don't want
too much of a prop load on it.

I'm sure that someone will be correcting me , but here is how I've
been doing it for the last 20 years or so.
I'm not saying this is the only way , but it definately works.

Using the smaller prop , start the engine and go to a real fast idle.
Let it run like this for a few seconds until you see that all is okay
with the engine , such as a knocking , something loose or any other
strange sounds. Now advance to half throttle and make sure it's
a little on the rich side before we go full throttle. After 30 seconds
or so goto full throttle and lean the engine to it's max rpm , then
......immediately..... back off a couple clicks. One wayto test to see
if you're at the proper needle setting is to pinch the fuel line for
about a half second or so. If the engine speeds up then you're pretty
much on the money. If it sags, it's too lean. We want the engine to
get hot but not overly so.

I always reach over and feel the head with my finger to check
the temp , I sorta slide my finger over the head or the side of
the crankcase. You should be able to make contact for a second
or two.
At this point in the break in it will heat pretty quick so stay with
it.
When it gets too hot to maintain contact , richen it a few clicks and
the head wiil cool quickly. Do the touch test , after cooling , go
back to the lean full throttle setting.s....two or maybe three clicks
from maximum RPM.
Do the fuel line pinch thing.

You can also use an Infrared thermometer to keep track of the temp ,
but I like this way better.

Do this through at least two tanks of fuel. Most engines will be
broken in enough to fly by then.

As I mentioned earlier , you will see the engine running cooler and
cooler at the same needle setting.

Another plus to breaking in this way.....your engine will turn more
RPM's and perform better than engines that aren't broken in
correctly.

After this , I would put the 11x6 on it and go flying.
But be sure you don't run too rich......or lean.

I hope this helps. Let us know how it goes.

Ken



.

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