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Old 09-06-2005, 08:07 PM   #1
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Default How much play is too much play Sirio .30 conrod


I just got this motor from the LHS and there hasn't been any fuel run through it. I noticed play in the conrod when the piston is at top dead center. At TDC the flywheel will turn about 1/8th of an inch back and forth and the piston will stay still. I removed the back plate and confirmed that the conrod IS definitely moving with the flywheel but not the piston. None of my other motors have done this (k 4.6 and STS .28). The hobby shop says that all engines do this but they are retards. Is this too much play?

Sorry the video was taken with a cel phone. You will have to have quicktime installed to see it.


Thanks I cant wait to seal it up and break it in, but if it is defective I don't want to go near it with RTV.
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Old 09-12-2005, 10:31 PM   #2
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are you sure your not just seeing the slight delay in movement of the piston as it reaches tdc and begins to be pulled back down by the crank. the sensation of play is due to the piston being static for a short period of time. just get the engine in bits and check for any play between the wristpin and rod, then you can be sure.
I'm amazed at how little pinch your engine has for a motor which hasnt had a drop of fuel though it yet!!
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Old 09-15-2005, 10:06 PM   #3
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The sirio 30 doesn't seem to have a ton of pinch, but I noticed on mine that after break in the compression was just about exactally the same as it was when it was new. And the case is still the same after a few gallons, lots of compression still.
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Old 09-15-2005, 10:38 PM   #4
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Sell that thing and fix your STS!
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