Silver Century plus not revving up

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seagull101
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Re: Silver Century plus not revving up

Postby seagull101 » Tue Sep 12, 2017 9:28 pm

Keith.P wrote:I just walked into the shed and opened one Amal carburettor float cap and I found.



I opened 6 and couldn't find one! But that is perfect proof of them existing!

Jacob

rstumpy
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Re: Silver Century plus not revving up

Postby rstumpy » Tue Sep 12, 2017 10:48 pm

Good idea Charles...in fact I'll twist a bit of 28 thou aviation safety wire in the notch and shim with some fuel proof little nylon washers that are around here somewhere.
My permanent abode is at 2600' above sea level, but where I am at the moment messing with this gull is about 45' above, about 60 miles upriver from Puget Sound...so effectively at sea level.

Keith--could you (when you have a spare minute) post the total length of your needle and the measurement to each notch from the pointy end?...would like to compare with what I have.

From the close proximity of the two notches my guess about compensation for different fuel specific gravities may be correct. Adjustment for use at different altitudes seems more likely however. Wonder why mine (and others) has only one notch.

Thanks much

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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Wed Sep 13, 2017 12:33 am

Minimum weight or you will change the height of floatation!
Make it idiot proof and someone will make a better idiot.

rstumpy
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Re: Silver Century plus not revving up

Postby rstumpy » Wed Sep 13, 2017 3:16 am

True that. Think I'll gin up a cork shim with a thin plastic keeper instead, or do rubber as you suggested. Going after more salmon in the morning so will test then.

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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Wed Sep 13, 2017 11:10 am

I t's a possibility that someone has replaced a faulty float, tested that runs, sell it, the wrong float could cause over fueling.

Measure your float, diameter & height & post a picture, so we can rule that out.

Bit late for Salmon isn't it?

Where did you find the jet sizes for the 46N?

Do any of your friends have a Seagull with one of these carbs, a complete carb swop might answer several questions.
Make it idiot proof and someone will make a better idiot.

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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Wed Sep 13, 2017 12:23 pm

It sounded like you doubted me there Jon, I'm nicknamed the Headmaster not the Bullshitter!

You can't expect to see everything in 4 years Jon, it's taken me over 20 years to learn all I know, & there are still big gaps.

It will be quicker to list what I haven't laid a spanner on, & that's SNP, SN, HSD, little model 40 F, LM & a kerosene Kingfisher though I've had a good look at all of those except the LM & the Kingfisher, the Cotswolds is a bit far for something that doesn't stimulate me & the gentleman researching those is doing a wonderful Job! & all the Kingfishers were for India I think.

Everything else I've probably owned!
Make it idiot proof and someone will make a better idiot.

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Oyster 49
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Re: Silver Century plus not revving up

Postby Oyster 49 » Wed Sep 13, 2017 5:50 pm


headdownarseup
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Re: Silver Century plus not revving up

Postby headdownarseup » Wed Sep 13, 2017 8:44 pm

More than 4 years now since i started messing about with gulls. An NO i don't doubt you Charles, but i have to check sometimes to be sure.
Closer to 15 years by now, but i'm not shouting about it.
Gaps.....yes.....but not necessarily from this end.



I could go back a couple of years with some of Charles previous comments on 102's but i'll spare his embarrassment as it'll only come back on me.

Cards have been marked, notes have been made.




Always good to have another interest somewhere else within the seagull line up, but my soft spot has always (and will always) be with the 102's even though i find myself looking more at the smaller 40's these days.


So, about this 2 slot float needle then. Was this a common fitment then or was it specifically targeted to overseas markets. True, i've stripped a fair few century's and 102's on the quiet but never seen one like this before. Like i said, i don't doubt anyone, i've never seen one is all, and i'm willing to bet that not many of you have seen one either!


Jon

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Re: Silver Century plus not revving up

Postby rstumpy » Wed Sep 13, 2017 8:50 pm

Couldn't get to the river today, but spending dinner gull tinkering. Had 46n jet sizes noted in my book and double checked here of course.

The float is an Amal 22/016, measuring 1.253" in dia and 1.316" from bottom to the top of the clip collar.
The needle measures 2.512" total length and 0.704" from tip to centre of the notch.

Went through things again and jets, body, etc are quite clean. Don't have a jet key with me but checked again with an indexed bit and confident jets are original for 10:1.
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rstumpy
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Re: Silver Century plus not revving up

Postby rstumpy » Wed Sep 13, 2017 9:31 pm

Charles,

Off-topic a bit, but...there are five separate salmon species that return to this river system (in Washington state, the Snohomish/Skykomish system) at different times of the year, plus both a summer and winter run of steelhead trout (7 to 16 lbs generally on steelhead). The fishing is a pale shade of what it was 40 years ago when I lived here as a boy, but still acceptable.
I have a 23' full keel offshore sloop and a deep-v 15' fishing boat back home, both nearly 60 years old and neither really suitable for river fishing in tight spots.

Rescued this nice little 13' rowing wherry and the seagull from being taken to the local dump a few weeks back. She handles most conditions quite nicely and is a sweet little boat. Also found two bent and broken aluminum trailers from which I made one from two. Total cost--$0...took a couple of evenings of spare time to clean up gull and boat to respectable condition and build the franken-trailer.

Makes for an extremely light package that pulls nicely anywhere with my little Subaru, as opposed to using my large diesel pickup truck. The wherry rows wonderfully but I'm glad it gave me an excuse to get back with Seagulls. Actually going to cast about for a forty plus which would be better on her for my purposes than the Silver Century (my opinion anyway).
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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Wed Sep 13, 2017 9:52 pm

The power jet is the important one, it's the taller one, on 1 side of the square bottom is a 2 digit number 40, 45 or 50.
40 = 25:1
45 = 10:1
50 = 10:1 cold climate.

If you have a 50 main jet in a warm climate you could get over fueling, which it what you seem to be suffering from.

Somewhere at home I've got the jet sizes, I'll have a look for them.

What's an indexed bit, not heard of one of them.
Make it idiot proof and someone will make a better idiot.

rstumpy
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Re: Silver Century plus not revving up

Postby rstumpy » Wed Sep 13, 2017 10:24 pm

I use indexed bits to confirm jet sizes in 1940's vintage aeroplane carbs since folks would occasionally drill them out slightly...makes the stamped number less than useful.
The jets are numbered as gull jets are.

#40 bit = 0.098" = 2.49mm
#45 bit = 0.082" = 2.08mm
#50 bit = 0.070" = 1.78mm

I gently inserted the smooth end of a #45 bit into the top (long end) of the power jet...snug fit...#46 was easy, #44 wouldn't go, so I made the perhaps questionable assumption that the jet index numbers are the same as the ones we use on aeroplane carbs.

I have a jet key at home but it's 300 miles away. I should probably just gin one up to be absolutely sure of this one.

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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Wed Sep 13, 2017 11:28 pm

I don't remember the sizes but they are measured from the bottom with pin gauges, I only have access to metric ones but they're a lot smaller than the top, I've got 0.7 mm rattling around in my memory.

Amal jet numbers relate to drips per minute, or so I was told by one of the Seagull old boys.
Make it idiot proof and someone will make a better idiot.

rstumpy
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Re: Silver Century plus not revving up

Postby rstumpy » Wed Sep 13, 2017 11:47 pm

Hmmm...very interesting.

Curiosity forced my hand. Worried the little devil out, and it is indeed a 45 jet. The carb is actually in nice shape. Just cant figure why it's having this issue with clean non-ethanol fuel and good oil mixed at 10:1. Makes no sense, it should be running fine in factory configuration....unless this needle isn't notched properly. Hate to do it but made some shims (of very light plastic) for the float and going to start testing.

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Charles uk
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Re: Silver Century plus not revving up

Postby Charles uk » Thu Sep 14, 2017 2:16 pm

Someone I sent the jet sizes to several years ago has sent them back to me.
Thanks Jez, saves me a 40 minute drive.

Idle Jet 25 = 0.425mm, 17 thou"
Power Jet 40 = 0.525mm, 21 thou"
Power Jet 45 = 0.625mm, 25 thou"
Power Jet 50 = 0. mm, thou"

These sizes are for a 46N twin jet carb.
Make it idiot proof and someone will make a better idiot.


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