Cubby Owners

[bluesmancoops]

As promised,

Managed to upload a short take-off clip from FAWI in the Cubby to YouTube so you can see the video quality.

http://www.youtube.com/watch?v=NoOwf8TyvkE

Thanks Clive .... I see they have a version 3 out now ... but I think the limitations of having to switch on manually "outside" the plane is a bit of a hassle and the guys recon that because of the auto light sensor, if put in the plane .... focus to the outside will not be good. Thanks anyway for the clip.

If you look here http://www.youtube.com/watch?v=quSPGHv0WMw you will see a short version of my cubby taking off and landing at morning star

[bluesmancoops]

has any other cubby owners wit VW engine had to replace fuel injectors and plug leads recently. My cubby started (what sounded like a miss) above Atlantis this am whilst I was up with my son causing some serious concern and was wondering if this was the injector going or maybe faulty lead, engine has been running beautifully for 12 hrs and then this?

[bluesmancoops]

well have bought new leads, coil and plugs which will fit tomorrow - thanks for the helpfull advice Trevor - hopefully this will solve the problem

[bluesmancoops]

I have ordered Great Plains assembly manual and DVD set as well as (How To Rebuild Your
VW Air-Cooled Engine) from http://www.greatplainsas.com/scbooks.html

As soon as I receive the set I will let you know how good they are, as I have also struggled to find decent info on the VW engine myself.

Hi Clive .... any news on this yet?

[tandemtod1]

I have had experience of this "miss" that you are referring to on 3 different Cubby's.
Les Maxwell's - now sold Chris van Niekerk - now sold and one old fart in Cato Ridge.
The symptom is a miss developing after 10 to 20 hours after fitting new spark plugs. When you fit new plugs the miss goes away for another 10 to 20 hours and then returns. Imagine the running costs if you buy leads, plugs and a coil every 12 hours. What next?
The problem on these three aircraft was as follows:
The rotor in the distributor did not line up correctly with the pole on the distributor cap when spark should take place. Even worse is that when the rpm's increase, the rotor advances away from the pole so the spark has to jump from the rotor to the cap pole.
To verify this, examine the rotor carefully and you will see that the rotor is nice and smooth across 99% of it's contact face so it looks pretty well unused, but right in the trailing edge corner, you will see a tiny burn mark. If this is the case, then only that corner of the rotor is being used and the burn is caused by the spark jumping a gap to the cap. As this progresses, less and less electricity is available to the plugs resulting in a "miss" If this condition is visible on you rotor, then go to Volksspares and purchase a CLEAR SEE THROUGH distributor cap and fit this to your distributor. Bring the motor to the firing point by observing the position of the disk relative to the hall effect sender and note the position of the rotor to the pole. If your distributor is missaligned like the other 3 Cubby's then you wil have to re profile the distributor to get them to match up.
Note that the miss will go away when you fit either a new set of plugs or a rotor. This doesn't mean that you have fixed the problem, the miss will return and this is quite dangerous as the miss will be at its worse at maximum centrifical advance.
Good luck,hope this helps

[bluesmancoops]

did u replace your distributor or not?

[bluesmancoops]

[quote="tandemtod1"]I have had experience of this "miss" that you are referring to on 3 different Cubby's.
If your distributor is missaligned like the other 3 Cubby's then you wil have to re profile the distributor to get them to match up.

how does one do this????

[clive layland]

Mike, I will only receive the books around the 16th December as I have asked one of the guys I work with to hand carry them in from the states.

Will keep you posted as soon as I receive them.

Hope you get the "Miss" sorted before this.

[bluesmancoops]

Mike, I will only receive the books around the 16th December as I have asked one of the guys I work with to hand carry them in from the states.

Will keep you posted as soon as I receive them.

Hope you get the "Miss" sorted before this.

Thx Clive hope so also

[tandemtod1]

You don't have to replace he distributor to cure the problem.
The problem originates by the fitting of the electronic distributor to the old 1600cc case. The gear is removed from the drive shaft of the distributor and replaced by the dog drive in order to get it to work and a compatability problem exists.
To re profile he distributor, you will need a black marking pen and a set of needle files (R40.00 from your local Midas) and circlip pliers
You have to work acurately so you need patience, if you mess it up you will need a new distributor (Goldwagen supplies to most of the people that built these engines)
Accurately set the engine to the firing position for any cylinder.
Mark the distributor position relative to the crankcase using your pen so you will know where to position the distributor when re- fitting it
Remove the distributor cap
Remove the rotor
Take careful note of the position of the window in the chopper disk relative to the hall effect sender
Remove the circlip that holds the chopper disc
Carefully remove the chopper disc ( it is fragile and easily bent) The centre of the chopper disc is steel so it is best to lever it off in the middle gently using two screwdrivers.
Locate the tiny key that positions the chopper disc to the distribtor shaft and remove it. Put it somewhere safe as you will need it again and your engine will not run without it
Put the chopper disc back on the distributor shaft without the key
Fit the rotor
Fit the clear distributor cap
Rotate the engine until the rotor correctly lines up with the cap pole making allowance for the advance mechanism
Once you are happy with the position of the rotor relative to the cap, remove the cap and rotor. Now rotate the chopper disc until it is in the firing position on the hall effect sender and accurately mark the position of the keyway onto the chopper disc. Remove the chopper disc and using your new needle files, file a new key way into the chopper disc and check for a good fit. When this is done, re assemble the distributor and re time the engine. Make sure that the rotor you are using has the wide contact on it and not the narrow one
Where are you based? If you struggle with this and you are not too far away I will come and take a look.
Happy Flying

[bluesmancoops]

..... on it and not the narrow one
Where are you based? If you struggle with this and you are not too far away I will come and take a look.
Happy Flying[/quote]

Thx for all the info I am based at Morning Star in Cape Town
What I can't understand (i am totaly technically challenged) how do the new leads and plugs temporarily fix the problem?? surely if the distributer is still suspect, the problem will still be there?

[tandemtod1]

You are quite right in that the problem still exists and is not cured by fitting new plugs leads etc. But by fitting these parts the SYMPTOM goes away for a short time.
The reason is simple. You are dealing with an item called electrical resistance. As the plugs get used, they burn slightly and get coated with carbon and other stuff which increases the electrical resistance and hence makes it more difficult for the electricity to flow which is when the miss surfaces. So by fitting fresh parts with a lower electrical resistance, the problem appears to go away but will return as the parts wear and the resitance increases. As an example, your ignition system which comprises of a battery, hall effect sensor, amplifier and coil (otherwise known as solid state ie no moving parts) will yield approximately 40,000 volts when measured at the coil output terminal. Once you make that 40,000 volts jump across the spark plug gap, it will drop to around 12,000 volts and your plug gap is only 0,7mm. So it is obvious that an air gap has large electrical resistance. Now make your 40,000 volts jump an additional gap like the one I have described to you inside your distributor and there isn,t much left over to fire the plugs.
If you are as technically challenged as you think, and I am in Gauteng so unable to help you, I sugest you get a good technition to inspect your distributor and take the necessary corrective action if required.
I hope that this has made things a little clearer for you and will help you in solving your miss. Feel free to ask questions if you need more info.

[bluesmancoops]

If you are as technically challenged as you think, and I am in Gauteng so unable to help you, I sugest you get a good technition to inspect your distributor and take the necessary corrective action if required.
I hope that this has made things a little clearer for you and will help you in solving your miss. Feel free to ask questions if you need more info.[/quote]

thanks for all the info - i will find someone down here who can help with the situation

[tandemtod1]

If you are going to fit fresh parts in order to carry on flying in the meantime, that is ok. There is one in Heidleberg been doing it for a couple of years already.
To make the miss go away for anothr 10 to 20 hours, you need to change the plugs and the rotor in the distributor. You shouldn't have to worry about the plug leads or the coil. Remember to buy the rotor with the wide terminal. If you continue like this, then I recommend that you replace the distributor cap every 50 hours as well
Good luck

[bluesmancoops]

Think I found the culprit

coil broke.jpg (32.1 KiB) Viewed 2612 times