Series 102 engine with a forty five blade prop

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african imp
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Series 102 engine with a forty five blade prop

Post by african imp » Fri Jan 04, 2019 2:12 pm

Having re built what is now a very decent 102 series engine from a crate of parts donated to me I find that the only prop that I have is a 9" five blade one marked 'Forty Only " can I use that type?

Correction, the prop is marked 100 only.
Last edited by african imp on Sun Jan 06, 2019 7:41 am, edited 1 time in total.

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Nudge
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Re: Series 102 engine with a forty five blade prop

Post by Nudge » Fri Jan 04, 2019 9:53 pm

If it will fit on the gearbox, then yes... but you will need to re pitch it or your engine will over rev and you won't go anywhere.
To re pitch the prop you need to anneal it first (this will help it bend) The aluminium needs to be heated up to the point where you can draw on it with a matchstick. You are not trying to light the match, but leave a black mark from it like drawing on paper with a pencil. The other thing you need is some way to measure the blades so they all end up the same. How much to bend them is a guess, try it and see. Take a block of wood and a hammer with you it your boat and you can fix it on the fly.
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african imp
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Re: Series 102 engine with a forty five blade prop

Post by african imp » Sat Jan 05, 2019 3:53 pm

Thanks,

What prop was this motor fitted with, I have read that a two blade one was used post WW2 but that was changed later, can anyone post a picture f a prop that I could use with out bending the blades of the one that I have?

RickUK
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Re: Series 102 engine with a forty five blade prop

Post by RickUK » Sat Jan 05, 2019 9:23 pm

Others may correct me, but for me, a blade marked 'Forty' implies 'Forty Plus' motors, and I don't recall any Forty Plus motor being fitted with a five blade prop.
The five blade props I am aware of - and I recall there were certainly three different sizes - were fitted to the 'Century' groups of motor, and were usually marked 'Century', '100' etc.

The 102 was variously fitted with a four blade 'Hydrofan ' type prop at some point, duly marked '102', the other 102 props being the swept-back two blade, the so-called 'bowtie' prop, and a broad-bladed three blade semi-weedless type.

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Hugz
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Re: Series 102 engine with a forty five blade prop

Post by Hugz » Sun Jan 06, 2019 12:15 am

Yep. If straight out exhaust.
15467299012055996831437975458126.jpg
If the pointing down exhaust (subejector)
15467300030157670106299721314118.jpg
Wow. I just accessed this forum by phone and took photo and it came staight on. So much easier. Except they are sideways. Note take photo sideways.
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african imp
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Re: Series 102 engine with a forty five blade prop

Post by african imp » Sun Jan 06, 2019 7:38 am

Guys, thanks on your replies and advice, I have just checked the five bladed prop and it is marked '100 only' not forty, my mistake.

The question remains will this five bladed prop be too small for the 102 motor?

Serial number TC 82813 circa 1962/63?

I have built this motor up from a steel trunk load of odds and sods that were gifted to me when an outboard motor shop changed hands, the 102 motor as seen in the picture did not exist, the parts did but it is a very much mix and match type assembly.

It runs well now and has a new owner, I have a second 102 option, a part seized power head and a selection of power legs, I will require another prop should it get re assembled?
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Hugz
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Re: Series 102 engine with a forty five blade prop

Post by Hugz » Sun Jan 06, 2019 8:21 am

Just pop it on a boat and try it. What ratio box are you using? They differ. You are asking us how long a piece of string is. What size boat are you pushing? What is the porting configeration of the barrel? What is the shape of the piston and the affect of scavenging? Which carburetor are you using and what size jets. Which magneto and the list goes on.

african imp
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Re: Series 102 engine with a forty five blade prop

Post by african imp » Sun Jan 06, 2019 11:11 am

Thanks for the advice!

Given that this entire motor was assembled from a spare parts offer I cannot say much about what your asking, excepting it has the Villiers coil and the carb came from John at SOS and was a body repair option on the lower thread, it is the Amal 2 jet version.

I will ask the new owner to test it out on whatever boat he has in mind.


I have just checked the gear ratio to motor turning, the motor needs to turn four times to one revolution of the propeller .

Regards

Roy
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RickUK
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Re: Series 102 engine with a forty five blade prop

Post by RickUK » Sun Jan 06, 2019 9:32 pm

So you have a 4:1 gearbox - I think this qualifies as a 'Barge pusher' (Hugz?? [good info on the props by the way]) which would be yet another prop! With that ratio, just slap the prop you have on and see how it goes.
A bit difficult to see from the photo, but it looks as though there is a large distance between the water pump housing and the prop spindle , which would also suggest the barge pusher prop, which was a big (13"dia.) four bladed cloverleaf affair.

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Hugz
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Re: Series 102 engine with a forty five blade prop

Post by Hugz » Sun Jan 06, 2019 9:43 pm

With the 102s I'm not the best to talk to on ratio's but l was under the impression the 1946 bargepusher was 4/1. The plus was 4/1 and standard was 2.5/1.

african imp
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Re: Series 102 engine with a forty five blade prop

Post by african imp » Mon Jan 07, 2019 6:45 am

My five blade prop looks like this.
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african imp
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Re: Series 102 engine with a forty five blade prop

Post by african imp » Mon Jan 07, 2019 6:49 am

I do have a larger prop but it fouls the gear box casing.

It measures 11.25 inches.
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