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Treblick's Nightmare
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3,671 Posts
Discussion Starter · #1 ·
It's mentioned in the service manual and I need to learn how to do it. Is there a step-by-step guide out there somewhere? Can someone clue me in here...
 

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Registered
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1,090 Posts
I dont know but WICKEDDREW just started a thread where he mentions plastgauging several times so maybe he'd know if you PM'd him.
 

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Ninja Performance
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42,336 Posts
When putting your motor back together Plastigauge is your friend, actually it is needed to do it right. You crank parts back together and they have a min and max clearance. So you place a plastigauge in between, crank the parts to spec torque, undue it and the plastigauge is flattened but only down to the space available between the two parts. This gives you the clearance between the two.

If it is too large or too small it is out of allowable specs and must be addressed
 

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14.1 @ 100mph N/A
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5,289 Posts
Plasti_gauge is little strips of plastic in different thicknesses. You snip off a piece and place it on the crankshaft journal between the rod or main bearings and the crank, then tighten down to spec. Then you remove the rod or main cap and hold the paper package from the Plasti-Gauge to see how wide the plastic is smashed to. That tells the the space(clearance) between the bearing and crank and tells you if you need new ones and if you need standard or oversized bearings.
 

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Treblick's Nightmare
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3,671 Posts
Discussion Starter · #5 ·
I read about it in the service manual in the section all about rod bearings and such. I knew it had something to do with smashing some sort of material but I didn't know how to measure it or anything.

Is this something I can pick up at any auto parts store? Is it fairly easy to use? Sounds pretty simple. Put it on, tighten everything to spec, remove and inspect.

So there is some sort of measuring device on the package to compare the smashed stuff to? I always wondered how to measure a flattened piece of platiguage. I was thinking along the lines of a micrometer or something.

You say it comes in different thicknesses... Do you have to use a certain thickness or will any do?

Thanks for the info guys.
 

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Official 3SI Mouth
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2,168 Posts
"Is this something I can pick up at any auto parts store? Is it fairly easy to use? Sounds pretty simple. Put it on, tighten everything to spec, remove and inspect."

It'll be stuck to the crank or bearing once crushed, but the package is a little paper envelope, so it's flexible enough to measure out proper.

"So there is some sort of measuring device on the package to compare the smashed stuff to? I always wondered how to measure a flattened piece of platiguage. I was thinking along the lines of a micrometer or something."

It's right on the package. The density of the Plastigauge is figured to a specific amount of crush- so if you take the same type of plastigauge and crush two bearings, one having a gap of .008 mm, and another with .010 mm, the one with the smaller gap will crush farther out.

"You say it comes in different thicknesses... Do you have to use a certain thickness or will any do?"

Yes. If I remember correct, it's Plastigauge green.
 

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Treblick's Nightmare
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3,671 Posts
Discussion Starter · #7 ·
Thanks for the answers. I'll post the results when my rods get here and I get the block back from the machine shop.
 

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14.1 @ 100mph N/A
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5,289 Posts
You can buy it at any Auto Parts store. It's behind the counter and costs $2.
 

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Jr Tech
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1,071 Posts
There are different ones also, some are for smaller and others for larger tollerances. Look in the manual and see what the tolerances are and chose the guage accordingly.
 

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Booooossstt
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6,788 Posts
In the tech manuals it mentions you need the green kind. Just to clear up a couple of things it comes in a paper package as mentioned with measurements already on the package. Tear off a secion about a half inch in length, open it and take the hairline wax out and lay it on the crank or whatever you are doing. Torque (DO NOT MOVE THE CRANK) undo the bolt and remove the cap gently and measure with the package. After you have measured then use your fingernail and scrape off all of the plastiguage! Do not leave any there as that does take up clearance.
sean
 
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