Technical > Matt Shaff's Engine Shop

Torque to turn over newly built SBC

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Ponti:
You having problems then? 

Frontenginedragsters:
PSweeney:
 We check piston ring drag when assembling an engine.
The oil ring is what we are looking at close. That is easy to adjust with different expanders.
Too much oil ring drag takes HP to turn the engine over. Low drag oil ring sets come in at about 18-25lbs of drag.
You can run less with a vacuum pump. Some ring sets we have seen as much as 50lbs of drag. Way too much !!
The common method of checking is to put the oil ring assembly on the piston. Oil the cylinder and put the piston and pin in upside down.
Push it all the way down and pull up with a fish scale hooked to the wrist pin.

Matt

PSweeney:
thanks guys, all sorted, seemed a lot but wasn't much more than 100ft lbs with valve train adjusted.

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