Hi all,

First of all my sincere apologies if what I'm about to ask has been handled in some topics before but I couldn't really find something that could be of any help.

Here's the thing; I have a Saito FA120 fitted inverted in a Spitfire and the first few flights were not as relaxed as I hoped whereas the engine can really be a pain in the *ss to start [:@]

Here's my setup:

Saito FA120 inverted
O.S. F glowplug
Kavan 17,5 fl oz tank, centerline fitted slightly under the spray bar.
felt clunk
18% Synthetic (Klotz) 10% Nitro
Idle and high speed needle are set correctly.

Here's what I do to get in fired up:

Fill the tank
Hand on the exhaust to get the fuel to the carb entrance, and just that in order to avoid a fuel lock.
No priming.
Check for a possible fuel lock by turning it over a few times.
Throttle stick at idle.
Attaching a glow-plug igniter.
application of the electrical starter.

In the first attempt the Saito starts and runs flawlessly but when the engine cuts for whatever reason, it won't start again. Then I have to turn the Spitfire upside down and place it in a stand in order to get engine going again. But even in a stand having the Spitfire upside down it can take up to several attempts before the engine finally fires up.

I've tried new glow plugs, let the engine draw in fuel by itself... and what not...

I'm convinced that there must be something I forgot but what?

Many thanks in advance!

Etienne

Etienne,

Do you use exhaust pressure on the fueltank air inlet? And if you do, did your try without?
The way you prime the engine, you do, so try running the engine without exhaust pressure.

Cees

Wrong post, deleted.

I had much the same problem with an upright Saito 1.20 big head with the 3 mixture adjustment carb. My engine quit a lot when the throttle was moved. Running without exhaust pressure as Cees suggests forces you to run the high speed needle open more. This helps make the midrange richer during throttle transition.

Is the engine fully run in ( broken in)?
And where is the tank located relative to the center line of the carb (vertically)

He said the "Kavan 17,5 fl oz tank, centerline fitted slightly under the spray bar."

When you say "1.20 big head" do you mean the early 1.20 ABC? I have one that I hope to run soon. What fuel and prop do you use? Thanks.

Sincerely,

Richard

Thanks I missed that as I was typing.

I thought all Saito 1.20 were ABCR. But yes I think mine was from 1983. Right around the time the FAI introduced the 20cc limit.

First of all thanks so much for the rapid responses!

Well as I mentioned earlier the centerline of the tank is indeed slightly below the spray bar when the Spit is sitting on its main gear. The recommendation of disconnecting the pressure hose from the exhaust is something to think about as I didn't test that yet.

The main problem I'm struggling with is that the engine just won't seem to start shortly after it died. It's like something seems to clog up the plug which I would suspect fuel or oil residue left from the first run. When the Saito stays alive after the first start, she runs great on the ground and after take off but after a flight when the engine is stopped and the Saito is started shortly after that it just refuses to fire at all

@Richard

Yep, it's an old ABC gold plated rocker cover FA120S but just broken in. I had the engine for quite some years but it's later used in this Spitfire.






It turns a Graupner 15x8... well, not in the picture but that MAS was soon replaced after this picture was taken.

Etienne,

Second important point for me is glow plug power.

Long wiring between "power panel" and plug for example can reduce the input power of the plug..
I do start my inverted ENYA 60 4 C with the use of this glowplug battery. No starter motor!
Lack of glowplug power can be a problem for the inverted engine when the plug has wet feet.

Maybe Mick knows a solution?
http://www.rcuniverse.com/forum/fb.asp?m=8150636



Cees.

I hope to install my 120ABC in my Spitfire also. It sounds like your starting problems might be a kind of vapor lock. Perhaps the heat of running and the heat buildup shortly after engine stop, since there is no cooling then, is causing the fuel to "boil" and keep it from starting. My old air cooled Corvair would not start right after shutdown because of this. Then I discovered thet there was an air flapper to be used in summer to cool the carbs. Maybe you can fit an insulator between the carb and intake manifold to keep the engine heat from being conducted to the carb. Like the gassers do. Just a random thought.

I see a couple Super Chipmunk in the background of your pics. I have the GP Giant version that I plan to put my FA180 into. I may convert it to gas/glow with a glow plug or to gas with ECDI.

Sincerely,

Richard

Thanks for the suggestions! Among them are some wich didn't cross my mind as of yet so I've got some 'work' to do

Tomorrow promises to be a sunny day again so I might test some of the idea's and see what it'll do with the Saito. All of this caused the Spitfire not be able to leave the pitts today and I hoped to see it fly like it did when the engine 'survived' the starting procedure so to speak.

As far as the cooling goes, I've had my doubts about the Saito being somewhat shrouded by the engine cowling which might prevent proper cooling by the airflow during the flight but I didn't really notice any cooling problems before...

@Richard,

One of the Chipmunks, the one in front, is mine and powerd by a Saito Fa91 mounted sideways or horizontal... here's a picture taken this morning flying in formation with an airliner :





...no problems starting whatsoever. With this Saito I do the same trick with blocking the silencer to build up pressure in the tank so the fuel flows to the carb but when the fuel reaches the carb I immediately stop so the carb won't spay fuel in the intake manifold. Just apply the starter and the Saito fires and runs without problems.

Anyway i'll keep you all posted!

What prop do you use ?

I have a SAITO 120S w/ Gold RK's and runs perfect....

[youtube]http://www.youtube.com/watch?v=ejTNK5kiaGQ[/youtube]

Hey buddy you left out some of the best pics! ;-)

Sorry that the spit didn't get a chance to fly today... And steal your prop so your chip was grounded too :-P
Here is a link to the 'vanessa rig' I mentioned to check the CoG:

www.rcuniverse.com/forum/m_708060/tm.htm

Hey matey!

Thanks for the link! I'll go into it a bit more tomorrow as I bookmarked it! Sure will help to get the C.G. of the Spit just right!

@Kostas1

The FA120 turns a 15x8 Graupner prop which remains to be tested as The Spitfire has flown only twice with this setup. Your engine is exactly the same as mine, a FA120s GOLD RK I guess that you don't have this problem? What do you do to start this engine without problems?

Hi again!

I must say first,
that i got the engine USED and since i got it i use only CoolPower 15% N-18% oil,
and APC 16x6.

I also use a Type F glowplug from OS.

The engine just keeps making me happy.

I start her normally,
using my Sullivan starter and a good prime.

One thing that i must point out is that i have set the HS NV at 1-1/8turns , out from fully closed.

A good prime would decisively turn into a fuel glogged glow plug or even worse; a vapour lock with my inverted Fa120. How do you prime your engine? I had the same issues yesterday despite disconnected pressure line. I might take it all apart this evening to see what's going on 'under the hood' as for fuel lines, tank condition etc etc...

Have you checked your tank height ?

I prime it ,
with my finder on the exhaust outlet and spinning 2-4 times the prop,
until i hear a nice "whistle" of the fuel in the carb !!!

Then i put my glowplug starter and Sullivan and bumm....

We usually don't get such problems,
in fact i've decided to install my new SAITO FA-150s INVERTED on my Giant Super Sportster !

Several gas guys using those felt clunks have complained about having fibers in the walbro internal screens. I have 4 saito 120s and run them all inverted but I use 10% nitro fuel with 18% synth/castor mix. I use a 3 line dual clunk tank setup. No prime to start, just verify no hydro lock and hit it with the starter. I also slot the cowl from the head back to make sure there is enough cooling.
How old is the engine? One of my high time engines (~ 200 hours) needed some carbon cleanup after about 70 hours run time. Which I consider normal since I use some castor in my fuel. That can give you some valve sealing problems.
Just some things to think about while digging around the bottom of the barrel.
Edwin

Edwin,

can we see some pics from your #3line fuel system ?

Do you know what brand of felt clunk they are using? I have Walbro carbed/klunked engines from 20 years ago and never found the problem on them or any of my later engines.

Thank you, I am sincerely interested in who made the errant klunks. I use Walbro Klunks with glow, gas and Coleman camp fuel.

Sincerely,

Richard

I dont use the felt clunks so I dont know anything about brands and have not personally experienced it. But there are severl threads here on rcu that mention fibers in the carb.
I dont have any pictures of my tank setup but its easy to setup. Dual clunk and one vent. The vent is standard setup. One clunk goes to the carb like a standard setup. The other clunk goes to a fill/drain line that is plugged and run outside the cowl. I've had way too many problems with 'T' fittings and fill valves and just dont use them anymore.
Edwin

The 120 I use is a model that isn't manufactured anymore.



I had the engine lying on a shelf for several years but it has been broken in just this summer and only has about 5hrs time on it. The felt cluck I use is a simple but effective Digitech.



I begin to suspect that the fuelpressure from the tank is too high for whatever reason which causes the engine to 'overprime' so the plug get clogged up in no-time... search goes on..

This is like the 120ABC I have (credit to KMOT for the picture) although mine has, and came originally with the gold rocker covers as on yours. Mine has the very effective air-bleed carburetor, does yours? Did you add the air intake venturi? Mine has a choke, does yours. Thank you, I am still trying to build information on my early Saito 120ABC

Sincerely,

Richard

If this is an FA-120 ABC,

mine is what ?

It has a curved intake..

Dont know the model name on that one but it preceeds the FA-120. I have 4 of the FA-120's with the cast intake manifold. The earlier one you are showing, from what I remember is a tube intake manifold. A buddy has one of those. Pretty old.
Edwin

Really old post. But Spaceworm. Your FA 120 ABC engine is there a D stamped on the right mounting lug.? I see in your photo your exhaust exits out the right side. Fat Head. Also your carb looks like it may have the adjustment disc. My FA 120 had a brochure dated 1983. I just overhauled mine.AJ