Featherweight box to 102

[O'Dubhain82]

H all. Just wondering if any of you racers can tell me the best way
to marry a featherweight box to a 102 top end?
The waterpump housing of the featherweight doesn't
line up exhaust wise and if I use the waterpump housing
of the 102, the screw holes don't line up with the featherweight
box. Do I need to make an adapter plate, or is there an easier
way?
Any ideas appreciated.

[charlesp]

Hate to say it but the easiest way is to get hold of the right gearbox...

[O'Dubhain82]

Normally you'd be right, but my plan is to build an engine
capable of higher speeds. Apparently changing the
gearbox ratio is essential.
Appreciate the reply though.

[charlesp]

Ah... I see now.

The other Charles will doubtless be along soon. I'm sure he will have some input here.

I imagine the exhaust diameter is the prime consideration.

[O'Dubhain82]

Come on lads! Let the secret out!

[rosbullterier]

I will be pleased when the other Charles explains because I have a featherweight box which would fit straight on (when I fit it)
He told me once why, and I have forgotten. Stupid . . .

[phil]

Get the water pump housing off a Century 100,which has the 40 style gearbox, but with a large exhaust. Bolt up to the featherweight gearbox.

[O'Dubhain82]

A Ha! Easy when you know how I suppose.
Thanks rosbullterier. Now I just have to convince "herself" that
I need yet another seagull.

[Charles uk]

PM me your landline number & I'll talk you through it.
There is a little bit more to it than RBT suggests, don't worry I'm on free calls to your place.
Charles

[rosbullterier]

-it was Phil who gave the info - why not talk us all through it?

[Rob Ripley]

You could just fit the 102 and exhaust to a 40 driveshaft and gearbox (just overlap the exhaust at the bottom) and the water delivery pipe will need to be straightened and shortened.

You could fabricate a 102 to 40 exhaust pipe, and do as above.

I have as you see got both .... even by swapping props, it doesn't seem to make any difference

[Charles uk]

Nice bit of work Rob on the diameter change.

Which prop are you using?

Seagull's own figures show that the longshaft version of a motor produces 2% more power than the short, thats why we don't reduce the exhaust volume.

There are no bolt on performance parts for any of the Seagull powerheads.

[Rob Ripley]

Which prop am I using?

Any of the 'small' collection.

[rosbullterier]

Very impressed with your metalwork but as Charles comments, your pipe also reduces the exhaust expansion chamber.

I don't understand - I thought the high ratio box was the Featherweight. If so, what advantage would the standard 40 box provide?

[O'Dubhain82]

Wow! Nice work there Rob. The graduated exhaust certainly
looks great but I think performance would suffer. Charles
has set me on the right track ( thanks Charles) on this and
many other speed related issues. A goldmine of tuning tips.
All I have to do now is buy more seagulls and start experimenting!