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Old Nov 26, 2012, 01:55 AM
Sticks, Tissue & old Diesels
brokenenglish's Avatar
France, Centre, Amboise
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Originally Posted by ColinNZ View Post
What model Mills is the one with the parallel fins.
Colin, I think the only Mills with the parallel fins is the very first one. The 1.3 Mk I of 1946.
And Reggie, you have your photo titles mixed. The repro Bambi is the engine with the red head. The photo you've titled Bambi is the Banks/VA half-size Frog 50.
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Old Nov 26, 2012, 02:36 AM
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Belgium
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Originally Posted by brokenenglish View Post
Colin, I think the only Mills with the parallel fins is the very first one. The 1.3 Mk I of 1946.
And Reggie, you have your photo titles mixed. The repro Bambi is the engine with the red head. The photo you've titled Bambi is the Banks/VA half-size Frog 50.
Thank you for the correction, some engines were not immediately registered into my collection-book, into which I do keep record of every engine in the collection with details and ser.nmbrs dates prices rarity etcetera
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Old Nov 26, 2012, 02:42 AM
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Originally Posted by Reginald View Post
Thank you for the correction, some engines were not immediately registered into my collection-book, into which I do keep record of every engine in the collection with details and ser.nmbrs dates prices rarity etcetera
And the very small black Mills is an 0.25 and the larger is 0.50
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Old Nov 26, 2012, 02:52 AM
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Auckland New Zealand
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Quote:
Originally Posted by brokenenglish View Post
Colin, I think the only Mills with the parallel fins is the very first one. The 1.3 Mk I of 1946.
And Reggie, you have your photo titles mixed. The repro Bambi is the engine with the red head. The photo you've titled Bambi is the Banks/VA half-size Frog 50.
I'm no Mills expert so i could be wrong but the crankcase ( or block) doesn't look like the one on a friends mark 1 it looks more like my mark 2
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Old Nov 26, 2012, 03:20 AM
Sticks, Tissue & old Diesels
brokenenglish's Avatar
France, Centre, Amboise
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Quote:
Originally Posted by Reginald View Post
And the very small black Mills is an 0.25 and the larger is 0.50
Reggie, unless VA changed their Mills capacities during the later period of production, I think you'll find that the larger of the two minis is 0.4cc, not 0.5.
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Old Nov 26, 2012, 05:00 AM
It must have a machinegun
Scaledown's Avatar
Perth, Western Australia
Joined Sep 2004
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What's wrong with my Snipe?

I've bought this ME Snipe and I've been trying to get it run properly. Apart from a scuff on the spinner it looks and feels to be in great condition. Compression is fantastic. It just won't break out of a 4 stroke. 6500 rpm is the best I can get with an 8x4 prop. Compression adjustment feels weird too. The difference between too undercompressed to run and overcompressed is only 1/8 of a turn. It chews fuel like its rich but it will conk out abruptly if I lean it any more.
Anybody got any ideas?
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Old Nov 26, 2012, 05:35 AM
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2 Cents from Sweden...

When turning the needle to the "bottom", does it really close....?....try to "close" the needle valve and check, by choking, if the engine still draws fuel.
If it does (which it shouldn't), the needle may have been re-soldered to the threaded part in the wrong position, i.e. the needle doesn't reach the bottom of its seat, and you cannot run the engine lean enough.....
This is not unusual when dealing with pre-"collector's engines"...it's worth a check.

Remedy: Re-check & re-solder...

BTW: Nice engine...

.
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Old Nov 26, 2012, 06:16 AM
Sticks, Tissue & old Diesels
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Another 2 cents from France.
Everything GH says is obviously good sense, but a good variation, when you've closed the needle as far as it will go, is to actually blow through a length of fuel tubing while gradually unscrewing the needle. This way you can feel and hear the variation in air passage, as the needle opens. As GH says, of course, with the needle completely closed you shouldn't be able to blow through.
Also, it's worth checking that the spraybar fuel feed hole(s) are properly positioned. They (or it) should be positioned transversally, i.e. facing the wall of the venturi. If there is only one hole and it's pointing down into the crankshaft port, the engine will still run OK but, in all cases, if you look down the venturi and you can see a hole looking back up at you, then the spraybar needs repositioning!
Finally, on the Snipe, the fuel tube nipple on the spraybar should be angled back towards the rear of the crankcase, which should more or less automatically align the spraybar.
Check that it is the correct spraybar, and that air isn't leaking in where the spraybar actually passes through the venturi (i.e. in the case of an undersize (wrong) spraybar with no fibre washer seals or similar...
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Old Nov 26, 2012, 07:59 AM
It must have a machinegun
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Perth, Western Australia
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Gluehand, yes the needle does seem to close properly.

brokenenglish, I didn't understand what you meant about angled fuel nipple until I just saw pictures in a 1962 engine test. My spraybar is straight, so maybe its not the correct one. The needle looks correct. The spray holes are aligned as you suggested but there are no fibre washers, so maybe there is an air leak. It certainly does not draw fuel well when choking. I have to keep the tank elevated to keep the air out of the fuel line. Maybe I'll make some thin washers from rubber. If its too thick the spray holes will not be central in the venturi.
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Old Nov 26, 2012, 08:42 AM
Sticks, Tissue & old Diesels
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Hi, Obviously, the diameter of the holes in the venturi should correspond to the spraybar diameter, plus a very slight clearance, i.e. the spraybar should be a "good fit" in the holes. If it can be waggled about, then it's probably undersize and may well be the spraybar from a smaller engine... This would mean air leaking into the venturi + excess venturi throat area due to the smaller spraybar diameter, which would give fuel draw problems such as you describe. If this is the case, you may have a spare NVA that is a better fit, somewhere in a box of bits. If not, find some fuel tubing that can just be pushed onto the spraybar (an airtight fit but not too tight). Cut two very thin slices of this tubing and use them as washers. Maybe my previous remark about fibre washers wasn't clear. I'm pretty sure your engine shouldn't have them, but they are a good "quick fix" if a spraybar is slightly undersize.
Basically, you just need to carefully examine the whole carburettor area, and make sure that the air being sucked into the crankshaft has to flow down the venturi, and can't leak in from anywhere else!
I don't possess any ME engines, but I think they have a separate carburettor venturi. Does it screw in? and if so, is it a firm airtight fit?
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Old Nov 26, 2012, 08:52 AM
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Another point worth checking up would be the backplate gasket.


Also: Maybe a "longer shot", though not an unrealistic one, would be checking the cylinder base gasket....
These later M.E. designs bear a strong resemblance to the DC engines, and I beleive (almost certain) that the Snipe shares the transfer port design with these, i.e. the thickness of the cyl. base gasket is critical to the transfer function.
Too thick a gasket will more or less block the transfer ports, whilst a too thin one will upset the timing...
But I would save this check until everything else has failed....

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Old Nov 26, 2012, 03:37 PM
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Marown Engineering NVA's

Here are my 2 M.E. Herons, one of each generation. The R/H one is the early version (all anodising gone though...) which differs at some points.
The NVA's of these are of similar type, as is also the one of this Snipe Marine (photo found on the web...), which indicates that the Snipe may have had two types of spraybars, the "straight" one, similar to the Heron, and the one with swept back fuel line fitting...

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Old Nov 26, 2012, 04:14 PM
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Mt Evelyn, Melbourne, OZ
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Quote:
Originally Posted by Scaledown View Post
I've bought this ME Snipe and I've been trying to get it run properly. Apart from a scuff on the spinner it looks and feels to be in great condition. Compression is fantastic. It just won't break out of a 4 stroke. 6500 rpm is the best I can get with an 8x4 prop. Compression adjustment feels weird too. The difference between too undercompressed to run and overcompressed is only 1/8 of a turn. It chews fuel like its rich but it will conk out abruptly if I lean it any more.
Anybody got any ideas?
This sounds like there is a leakage of crankcase compression.
If crankcase compression is poor, then the engine will only run at all on a very rich setting.
My Snipe also had this problem, someone had fitted a gasket under the cylinder obviously trying to imporve carnkcase compression, but it also blanked off most of the transfer port area.
When I removed the gasket and tightened down the cylinder as hard as I dared, the problem disappeared and now the Snipe runs really well (at least as good as my blue head Frogs) and is a first flick starter.
I'm not really sure wheteher there is supposed to be a gasket or not, but mine now runs so well without, I will not disturb it again.
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Old Nov 27, 2012, 12:24 AM
It must have a machinegun
Scaledown's Avatar
Perth, Western Australia
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All good information fellas.
OK, I think I need to do some pressure tests - blow air into the venturi and look for leaks around the needle, venturi base, backplate and cylinder.
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Old Nov 28, 2012, 07:33 AM
It must have a machinegun
Scaledown's Avatar
Perth, Western Australia
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I have some experimental findings to report.
I found a plastic pipe that would fit over the verturi then I immersed the engine in a glass of kero and blew into the pipe. The first thing I saw was lots of bubbles from around the NVA nuts. Then I rotated the crank until the piston was just blocking the exhaust port. Blowing again, bubbles streamed from both exhaust stacks.

The cylinder on the Snipe does not screw into the crankcase. I just rests on a narrow shelf machined inside the crankcase. Screwing on the head holds the whole thing down with enough force in theory to make a seal. The bottom of my cylinder has some blemishes, either manufacturing faults or dents from being dropped. Its possible this is where the leak is. To test this I put a heap of grease around the sides and base of the cylinder and repeated the pressure test. No more bubbles from the exhaust stacks.

Its starting to make sense. The engine would start best when I gave a huge prime down the venturi. That would wet the cylinder base and make a bit of a seal. After about 2 seconds the engine would sag and usually stop. That was probably the fuel being burnt off and the leak returning. I'll bet with all that grease I could get a whole 10 seconds of running.

Now I have to figure out how to make it seal permanently. Araldite is looking attractive.
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