Whittle Aero V8 WIP

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dieselpilot

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With 8 cylinders I would think the compression feel would be quite a bit less as you have 4 cylinders with some pressure in them. The torque variation between TDC of cylinders is smaller. If you pull plugs on all but one and you can't feel compression, then there may be some issue.

Also, I see that you have a standard rotation prop on it. Previous discussion here said that the engine is cammed to run the the other direction?
 

GRAYHIL

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Standing behind the engine and from there turning the prop C/W I get the following:-
At tdc on no 1 cylinder both valves closed

1/2 TURN C/W AT BOTTOM OF STROKE
Exhaust starts opening

1/2 TURN C/W AT TOP OF STROKE
Inlet starts opening

1/2 TURN C/W AT BOTTOM OF STROKE
BOTH VALVE CLOSED
Back to TDC

Also every 1/4 turn c/w gives 1,4,3,8,7,6,5,2 valves closed at tdc per cylinder.
All parts made to drgs. and Model Engineer instructions
Have yet to test carb arrangements
Graham
 

dieselpilot

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OK, that sounds normal. I'm working on a CAD model of the engine and haven't reached the cam yet. The engine doesn't have overlap so the valve action you describe is correct.

Methanol is fairly forgiving on the rich side of mixture. As long as the plugs are hot it should fire even if things are very wet.

What are you driving the plugs with? The large two volt battery recommended in the article is probably the best way to light 8 plugs at once.
 

fcheslop

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Hi Graham, the glow plugs are wired in parallel due to there being 8 you need quite a large battery as recommended in the write up.The position and depth of the plugs is important to the running as are the ventures.The compression improves as the engine beds in .
Regards Frazer
 

poelafourie

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I am really looking forward to follow the progress, keep us posted!

Poela Fourie
 

gadabout

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sorry, I am a bit confused, your saying your turning the motor clockwise to check the timing but the picture shows a prop for counter clockwise operation, which way are you flicking it to try and start it? or is the picture mirrored? O am I confused?

regards
Mark
 

GRAYHIL

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Hi Mark
Standing at the front of the engine anti clockwise (a/cw)
Standing at the back of the engine clockwise (c/w)
The propeller sucks air in and blows air over the engine and backwards towards the fuel tanks.
So with an electric drill as a starter I turn it from the front on the spinner anti clockwise (a/cw)
Graham
 

dieselpilot

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What is the output RPM of your drill? Little cylinders like to spin fairly fast. I work with model airplane engines a lot. I set up a starter with a high voltage battery to turn the engines over quickly to eliminate that issue when I'm experimenting. I would make sure the starter can turn the engine over at least 2-3000 RPM until it's run in well and priming and carb settings are sorted.
 

GRAYHIL

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Hi All
So I have got a couple of things to try, (at the moment I am putting in a coolant tank, pump & nozzle on the lathe, not a long job but messy.)
1) Take all but one plug out and try compression again.
2) Try lowering the fuel tanks more level with the carbs.
3) Get a faster starter drive motor.
4) Try and drip a few drops of fuel in the carbs.
4) Recheck the carbs and needles.
5) !!!!!????
Incidentaly I cant open and view the 4 pictures I posted on the website, can any of you.
The picture of the fuel can was a way of asking if it was the correct fuel to run the engine on??? what do you use?
Graham
 

cidrontmg

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All pictures open just fine. Your fuel seems just the ticket, but the fuel tanks are quite high for the carbs.
 

GRAYHIL

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To test the air tightness, not the pressure, I made this



It screws into the spark plug hole and with a drop of fuel inserted with a shringe and the plastic tube held in a U shape and then the engine turned to top dead centre the fuel rises up the tube approx 6".
If the engine is left stationary at this point the drop of fuel does not descend.
It will also suck the drop back on inlet stoke if I remove the pushrods
and on through the cycle.
I think this proves the system is airtight, but not pressure tight. Another step hopefully in the right direction.
Graham
 

walnotr

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Rob.Barrett said:
Camshaft blank and camshaft finished.

Rob.
Rob, that's looking really good! :bow:

I wonder how many Whittle builds are currently underway. I hope to be finishing up the crank case soon so I can move on to other parts.

Steve C.
 

stang6t8coupe

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Hi,

could anyone tell me where i can find the plans for this engine? The links that have been posted on page 24 don't work.

Is there a shop where i can buy the plans as pdf?

Thank you
Adrian
 

MachineTom

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I came to the site yesterday and read Cobra's posts on the Whittle project. The posts just stopped in July from Tony, anyone heard from him? Health issues or ?
 

waynes world

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stang6t8coupe said:
Hi,

could anyone tell me where i can find the plans for this engine? The links that have been posted on page 24 don't work.

Is there a shop where i can buy the plans as pdf?

Thank you
Adrian
you can get them from the model engineer site from the uk magazine site free as they put them up for people to enjoy as they felt it was time for it create intrest for the site . not a rip from just anybody.www.modelengineer.com.uk
 

steamer

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THAT is a Jewel!
:bow: :bow: :bow: :bow:

Keep it coming! I'm loving it.

Dave
 
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