Little Model Forty F (1949/50)

[Charles uk]

I echo Bruce's comments, whilst the anoracks amongst us, myself included would like you to photograph & measure all it's powerhead internal components, you could be opening Pandora's box.

Without access to a mate in a machine shop or a career in engineering, I'd leave the powerhead internals well alone, the chances are that the cylinder studs (that extend from the crankcase to the cylinder head) & the mild steel gaskets on either end of the cylinder are probably at the end of their usefull life & the crankshaft, conrod & piston or any part of which the cost of remanufacture could well exceed the final value.

This is a very rare early small Seagull, not the rarest as there are a couple of examples where only one is known to survive, but the chances are that more will appear, 5 more Marstons did in the last 12 months, if they're small & cute, people are less likley to evict from the shed, so keep your eyes open.

With regard to the compression, even with a lot of thick oil, 170lbs is very high, as these motors were designed to run on post war low octane fuel, us oldtimers can remember the sound of pinking in their fathers car, a noise that is soon terminal in a two-stroke.

[Oyster 49]

What engines are there with only one example known Charles? I'm intrigued.

[Gannet]

Thank you all for your interest and advice. it is much appreciated.
I am beginning to feel that I almost don't own this little motor, following the all the advice and comments as what to do and what not to do! I will, I promise, look after it and treat it as if it belongs to the wider Seagull fraternity, with the aim of maintaining/restoring it for the future.
Your advice will be critical as I am a relative newcomer to Seagulls, so please keep the advice coming.
Please don't expect instant results. My plan is to carry out simple cleaning and examination, followed by a trial water tank run. After that I will decide on whether to remove the head and block.

The biggest help I need now is to find an amal carb. Any ideas? This carb would, surely, have been made in volume for other small engines (eg mopeds) as well as outboards like the Anzani Pilot.

The compression figure of 170psi is high. However I did infer that all the oil would have provided a very good seal.
In a previous topic on this site, there was discussion on values. I think that the effect of increased volume in gauges and any pipework is not always taken into account. Boule's Law is very relevant here. My gauge is of very small volume and screws almost directly into the 18mm plug thread. This set up will give a higher reading that a gauge on the end of a pipe.
Do you think that I should investigate this high figure before trying to run the engine?

Thank you for your interest.
There is still room around my tree for an Amal!
Jeremy

[Charles uk]

I'm not going to start a searching or cloning frenzy Adrian.

The normal method of taking the compression is to keep pulling over the motor until the pressure won't go any higher, which tends to cancel out any internal volume differences in the gauges.

[Gannet]

Hope everybody has survived the eating, drinking and talking frenzy that is part of Christmas.

Yes, 170 psi is high, perhaps my gauge, as you suggest is faulty. I have seen set ups where the non return valve is fitted in the end of a hose at the other end to the head connection, resulting in low values.

I have now removed the gearbox and examined the pump rotor. This is loose on the shaft - approx width across the flts is 0.52/0.53. The shaft being as usual 0.50. This clearance does not seem to have been caused by wear or corrosion. The O/D of the rotor is bgger at 1.52/1.54 compared to my FV at 1.44. Is it possible that the shaft/rotor clearance was to enable the rotor to centralise itself in the housing bore?
I am inclined to reassemble, but would like to understand why it is differeent to the FV.

As requested I have attached photos, including the transom bracket. The aluminium 'cotton reel can be seen, with the flash line indicating a casting. The bracket on the right is from an FV.

Jeremy

[Oyster 49]

Excellent Is that a bronze impeller? All the FVs and FVPs I have looked at have aluminium impellers, as does the 1955 SJM that I've just put back together.

Perhaps the original F model was put into production, and then it was realised that improvements could be made, in performance, cost, ease of manufacture etc? So after the initial batch they switched to the FV with the villiers carb, and other differences.

[Gannet]

My experience is a little different.
FV1786, FV1867T and FV2682 are all fitted with tight fitting bronze rotors.
SJM35 is fitted with a black plastic rotor (it looks a bit newish).
I have also an aluminium rotor off an FV of unknown serial number.

Does this help?
Jeremy

[Collector Inspector]

Here is the carb number for the Pilot. It fits a 19mm stub.

359/087E

The 359 is the type. The pics show no thread for the storm cowl/choke to screw on to and the float bowl top is attached with two screws.

When comparing with the Charles pic there are too many differences for the Pilot carb to be "The Same"

The Excelsior Super-Autobyk had one. It was apparently a 359/001B. Maybe if you search locally, you may find one. With some luck it will be as Charles pic.

Learnd sumfing today

B

[Oyster 49]

I have a 359 fitted to my ferrier, and there is another on eBay at the moment. Both have two screws holding the float bowl top on, so not quite right for the little 40. Very close though!

http://www.ebay.co.uk/sch/i.html?_nkw=a ... 359&crdt=0

[Gannet]

Thank you both for the info on the Amal carb.
As you said it is not quite right for the F.
Do you think, however, that one of the 359 series is the right one? I don't know how Amal's numbering system works - perhaps there is a 359/XXXX with a screwed on top to the float chamber and a top fuel feed? Or do you think it is a different number entirely?
Do you know whether the numbers are on the carb, or is it just the basic cast number?
Jeremy

[Gannet]

Is it too early to claim that one has survived 2012 ( especially as the world didn't end the other day)?

Anyway to less important matters - to my recently acquired F201.
After tank and plug cleaning and adding some old petroil, it started first pull, and (in inexperienced opinion) ran quite smoothly with a good steady stream of water. I am very pleased indeed. This was of course using the Villiers carb that came with it.
My immediate decision is to leave the head/block alone - apart from cleaning and painting.
After the engine has drained properly, I will, as I do with my other old engines, pour dewatering oil into the block. This, I think must help to reduce corrosion.

Jeremy

[Horsley-Anarak]

If you turn the engine upside down after running, be aware that water from the water pump can go down the drive tube, and end up in the crankcase.
I have an as new century that had the water passages filled with oil, but crank and cylinder ruined.

H-A

[Gannet]

Yes, thank you for pointing that out. I will now take extra care. Could water also get into the crankcase from the exhuast pipe? I expect it can.
Anyway, as I said, I let the engine drain first. I also tilt it in various dirctions to get pools of water to drain out.
Cast iron, especially when rusty can be very porous. How successful dewatering oil is getting into the porous parts and displacing water, I don't really know. On the surface it will displace water very well and will provide, for a limited time, a barrier against water and oxygen.
Thanks for your warning/advice.
Jeremy

[Gannet]

With the posting about Champion 8 COM spark plugs I was wondering whether any of the three Lodge plugs that i have are suitable and contemporary with the 1949 Little Model Forty F.

These Lodge plugs can be stripped down. One is a C3, another CB3 and the third does not have any identification apart from 'Lodge'.
The insulator on all three is a pink colour. They all have three earth contact points.

I would appreciate any comments as to their suitability.

[Niander101]

No pic of them ?