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PostPosted: Tue Mar 06, 2012 7:35 pm 
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998cc
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Joined: Sat Jul 14, 2007 1:42 pm
Posts: 903
Location: Hunter Valley, NSW
OK so I have the crank in. Spins nice and free and when torqued to 60 ftlbs all is still smooth and cranks turns with no tight spots. Thats all good. Put the conrods on crank (not in the bores but in the open with the engine upside down) and check that they are OK and not catching on anything. All good

One by one put pistons now connected to conrods into the bores. Noticed that it is easier to turn crank with piston at either top or bottom of stroke. Seems a little harder to turn when stroke is in the middle of the bore.

Is this normal?

Put other three pistons in and feels about the same - easier to turn crank with pistons at the top (1 & 4) and bottom (2 & 3). Slightly harder to turn as pistons come up and down the bore.

Have checked and yes the rods have the correct offset in 2 & 3.

So what do you think?

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Dave K.
1979 Moke Californian + 1981 'Coke' Moke


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PostPosted: Tue Mar 06, 2012 7:48 pm 
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1098cc
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Joined: Tue Aug 05, 2008 8:03 pm
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Location: Qld, Brisbane
What i just read, provided i understood it, sounds fine.

When the crankshaft turns at a constant speed, the pistons will not be moving at a constant speed. They will be moving faster through the middle of the bore. So that means that when you turn it by hand, it will take more effort to spin the crank through the middle of the stroke because the piston rings are dragging over a greater distance.


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PostPosted: Tue Mar 06, 2012 8:11 pm 
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Joined: Fri Mar 19, 2004 6:19 pm
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Location: near Baulkham Hills, NSW
Sounds normal to me Dave.
Matt's description sums up why.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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