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| Rebuild: How easy to turn crank with pistons in? https://www.ausmini.com/forums/viewtopic.php?f=5&t=75832 |
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| Author: | miniDave [ Tue Mar 06, 2012 7:35 pm ] |
| Post subject: | Rebuild: How easy to turn crank with pistons in? |
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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| Author: | mini_mad_matt [ Tue Mar 06, 2012 7:48 pm ] |
| Post subject: | |
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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| Author: | drmini in aust [ Tue Mar 06, 2012 8:11 pm ] |
| Post subject: | |
Sounds normal to me Dave. Matt's description sums up why. |
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