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| Size differences between 2 1/2 HP & 3... |
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wombat
| | Posted on Sunday, September 29, 2002 - 12:07 am: | 
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I've got a customer who want his 2 1/2hp chapman fitted into one of the launches that I build, however, he's in Sydney, and I'm in Melbourne.... I have a 3 1/2 hp Chapman master Pup engine, and I'm wondering if the distance from the flywheel centerling to the bottom of the engine beds is the same, and if there are any other size differences that may affect fitment. I'm guessing that the only difference is stroke, but I can't be sure.....
I've also got a couple of boats here suitable for single cyl inboard power if anyone's interested...... |
marks
| | Posted on Sunday, September 29, 2002 - 06:50 pm: |
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Rob,
Be careful of this. If his motor is a 2 1/2 pup then the drive is off the flywheel. All the other Blaxlands I have seen drive off the opposite end of the crank(ie magneto end).
You may need to check this with him. It sometimes becomes difficult to match the flywheel centreline with the usual shaft centreline without moving the engine forward(otherwise the flywheel fouls on the bottom of the boat). I think they have a 10" dia flywheel.
If I remember correctly the 2 1/2 HP is different to the the other Blaxlands in that the that it has a split crankcase with the cylinder and top crankcase half being one casting. If this is the case then the top of the engine mount flange casting should be on the centreline So the engine beds are lower than the centreline by the thickness of the engine mount flange.
I hope this makes sense.
If you customer cannot supply the drive config, flywheel dia or any other info I can probably find out.
Good luck
Mark |
wombat
| | Posted on Monday, September 30, 2002 - 06:48 am: |
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Thanks, mark.....
quote:
"If I remember correctly the 2 1/2 HP is different to the the other Blaxlands in that the that it has a split crankcase with the cylinder and top crankcase half being one casting."
My 3 1/2 (or is it 3 1/4?) is exactly the same; the lower part of the crank case is integral with the engine beds, while the top half of the crankcase is integral with the cylinder block. The clutch is attached to the flywheel; The other end of the crank has a bevel gear pressed on, to drive a vertically mounted magneto, making for a very compact installation.
By the sounds of things, my engine may be the same.....  |
peter ogborne
| | Posted on Monday, September 30, 2002 - 07:25 am: |
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wombat........if you are stuck let me know . Amongst my books i have a dimensional detail of both engines . At the moment they are packed away in a box somewhere . I am moving to another location in WA but i will unearth them at some stage ........the info you have been given sounds good to me . |
wombat
| | Posted on Tuesday, October 01, 2002 - 07:21 am: |
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Spoke to my customer today, he will confirm the relevant information for me, but had an interesting story......
Apparantly the person who he bought the engine from (who had reconditioned it) has since told him that the 2 1/2 & the 3 1/4 are the same, just rated (carby jets different?) for different revs!!!
Always interesting hearing different stories!! |
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