This Project started shortly after the sale of the guinea pig in early June 2004. The guinea pig, which I had had for longer than I care to remember was very under powered for my new dinghy. Thats not too much of a problem as I have a 5HP Mariner but how the hell can you run a seagull website if you dont have an engine for your dinghy !
I decided I would buid a seagull up from scratch. I gathered a few parts together and started assembling them. Most were from a model 75 I picked up on ebay a few months ago. I decided I would use a Model 102 cylinder block. This was for 2 reasons. Reason 1 is it is the only engine I have yet to hear run ! 2 I always do silencing conversions and the Model 102 block already has these fitted.
I also decided to use the mark 4 ignition that was unusually in the model 75, I was expecting a mark 3 but the mark 4 was a result. They are mainly used on the really late seagulls and the QB's. They also have a facility for a kill switch.
Other parts used are - Model 75 sealed clutched gearbox with weedless propellor, Seagull alternator, stainless steel exhaust.
This is the engine in the process of being built up. I had a lot of problems connecting the water deliver tube from the model 102 block to the model 75 gearbox. A little bit of manouvering got it in the correct place. The gearbox had all of its seals replaced and a fresh coat of paint. I also had to make up an exhaust tube and drivetube as the length of this engine is not a standard length.
So have you spotted the diffence yet, I bet you haven't. If you look at the picture above the 3 above you will see if you look hard that the flywheel cover is different. I had to change it as the two holes use to retain the recoil starter had been drilled out ! Lucky I managed to aquire another and the "bluetop" recoil which I might add have never been used.
You may also notice that this engine has an extended tiller arm, this was originally made for the guinea pig. This will also be modified as I have a seagull twist grip throttle assembly but this is going to need a very long throttle cable !
The picture above show the alternator stator assembly inside the flywheel cover and the alternator rotor sitting on the top of the flywheel. The alternator was very easy to fit which surprised me, It took about 5 minutes but the flywheel assembly was apart already. If you are thinking of getting one, I reckon you would need about 20 minutes. This alternator was purchased on ebay but typically I now have 2 of these as one was in with a job lot of spares I have just bought. The Seagull alternator delivers about 4 amps This can also be reduced to 2 amps by simply turning the plug around on the lead.
The picture above shows a QB series impellor next to a standard one. The diameter of the QB impellor is slightly bigger than the standard but would possibly fit in the housing. This is a thought for the future for test purposes. If the QB impellor fits there is no reason why it wouldn't fit in any other seagull.
I have a feeling that this engine is going to be highly experimented on. There are a few things that I still need to work out before it gets put into service. I noticed that water bubbles from the top of the exhaust tube so I am planning on a spraybar inside the exhaust to more acurately divert the water flow from the cooling system. I also have not placed any stainless steel scourers in the exhaust as yet. The model 102s do not usually have holes drilled in their exhausts and I am a bit worried about exhaust back pressure. I am also keen to find out how much power is lost when the alternator is being used. I will keep this page updated as the experiments continue.
February 2004
Since Writing this page this engine has been used quite a few times and is running very well. I have repainted the top of the recoil starter to match the tank and fitted a twistgrip throttle. I also at the same time removed the old amal 2 jet carburettor and replaced it with an amal 418 which is normally fitted to a QB series Curlew. I had to make a throttle cable up which I made from a high quality Halfords bicycle brake cable. Updated pictures below.
