Spun Bearings again????
spun bearings
For what it is worth, you can't use plastigauge properly with the block in the car. All of the main bearings are acting to hold the crank in the block. This means that all will show very tight tolerances becaust the bearing cap will "lift" the crank as it is tightened giving you a false sense of tight tolerances. The same is true of rod bearings even if you pull them down on top of the journal. I guess the force required to move the pistons in the bore is greater than the force requires to flatten the plastigauge. I have seen rod bearings showing lots of copper read .00015 with plastigauge while the engine was still in the block. The actual tolerance was more like .0004-.0006. Typically I only use the stuff with the block inverted in an engine stand. With the mains you put the plastigauge on the bearing cap half whereas you put it on the rod half when doing the rod bearing clearances. Never put it on the bearing half that will be pulling the assembly together because the reading will be junk.
bastard.. youll pay for that..
Originally Posted by smokedmustang
Thanks silverghost and dafarmer!! Great info for me and the others reading this. time to go to Buschur!! Thanks again, you guys are very knowledgable, dafarmer must have been reading and plagerizing a book. you are ill, and couldn't possible write that concicely. I think the "joe dirt" part is yours though!
Originally Posted by silverghost
For what it is worth, you can't use plastigauge properly with the block in the car. All of the main bearings are acting to hold the crank in the block. This means that all will show very tight tolerances becaust the bearing cap will "lift" the crank as it is tightened giving you a false sense of tight tolerances. The same is true of rod bearings even if you pull them down on top of the journal. I guess the force required to move the pistons in the bore is greater than the force requires to flatten the plastigauge. I have seen rod bearings showing lots of copper read .00015 with plastigauge while the engine was still in the block. The actual tolerance was more like .0004-.0006. Typically I only use the stuff with the block inverted in an engine stand. With the mains you put the plastigauge on the bearing cap half whereas you put it on the rod half when doing the rod bearing clearances. Never put it on the bearing half that will be pulling the assembly together because the reading will be junk.
I don't agree with working on internals with the block in the car, neither do I agree with the use of plastigage in any situation.
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