Here Is A Polish Idea- Why Won't Plastigauge Work ?

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73 Mustang Convertible
Born an I-6, spent the teenage, 20 and 30 years as a 302, but at 40 will reach full potential as a 351C.
In my travails to blueprint my motor, I was significantly more adept at the use of a micrometer as opposed to the bore gauge.

As a result, I was trying to conceive of a way to use a micrometer to measure the bore...silly isn't it. How to use a device used for measuring OUTSIDE diameters for an inside diameter...

But then, I was hit with one of those brilliant flashes of lightning ideas:

Why can't I put the plastigauge on the crank and squish the plastigauge down as is the typical practice. But, instead of measuring the width the plastigauge has squished down to, why can't I just use a micrometer to measure the crank with the plastigauge on it? The plastic has been smooshed down to a height equal to the clearance between the crank and the bearing. Can't I just take my micrometer and measure the cranks diameter at the plastigauge?

What is your opinion?

What were my results?

Voice your opinion....results Sunday.

 
In my travails to blueprint my motor, I was significantly more adept at the use of a micrometer as opposed to the bore gauge.

As a result, I was trying to conceive of a way to use a micrometer to measure the bore...silly isn't it. How to use a device used for measuring OUTSIDE diameters for an inside diameter...

But then, I was hit with one of those brilliant flashes of lightning ideas:

Why can't I put the plastigauge on the crank and squish the plastigauge down as is the typical practice. But, instead of measuring the width the plastigauge has squished down to, why can't I just use a micrometer to measure the crank with the plastigauge on it? The plastic has been smooshed down to a height equal to the clearance between the crank and the bearing. Can't I just take my micrometer and measure the cranks diameter at the plastigauge?

What is your opinion?

What were my results?

Voice your opinion....results Sunday.
The plastigauge takes itself into account. So where does that leave you.

 
I would measure the crank and then add what the platigauge tells you to it to get your answer. If you try to measure the plastigague itself, you will probably squish it.

 
Kinda defeats the purpose, I would think, if you have to measure the crank + Plastigauge with a micrometer vs Plastigauge reading after cranking down the crank. Then again, it might be that I'm just feeling a little cranky. :dodgy:

 
In my travails to blueprint my motor, I was significantly more adept at the use of a micrometer as opposed to the bore gauge.

As a result, I was trying to conceive of a way to use a micrometer to measure the bore...silly isn't it. How to use a device used for measuring OUTSIDE diameters for an inside diameter...

But then, I was hit with one of those brilliant flashes of lightning ideas:

Why can't I put the plastigauge on the crank and squish the plastigauge down as is the typical practice. But, instead of measuring the width the plastigauge has squished down to, why can't I just use a micrometer to measure the crank with the plastigauge on it? The plastic has been smooshed down to a height equal to the clearance between the crank and the bearing. Can't I just take my micrometer and measure the cranks diameter at the plastigauge?

What is your opinion?

What were my results?

Voice your opinion....results Sunday.
Mic the crank. Lock it. Set the bore gauge to be slightly bigger than the mic. Place bor gauge in the Mic and while it is in the mic calibrate the dial to zero. Now place bore Gauge in the bore and subtract to get the difference, Unfortunatly the gauge will move backwards so count increments instead of looking at the numbers. You can flip some steps around to make the gauge read properly, but I don't because apparently I think backwards naturally.

 
Mic the crank. Lock it. Set the bore gauge to be slightly bigger than the mic. Place bor gauge in the Mic and while it is in the mic calibrate the dial to zero. Now place bore Gauge in the bore and subtract to get the difference, Unfortunatly the gauge will move backwards so count increments instead of looking at the numbers. You can flip some steps around to make the gauge read properly, but I don't because apparently I think backwards naturally.
That is basically how I used the bore gauge.

However, why go to the time and expense of a bore gauge?

Why not just mic the crank at the plastigauge, subtract the value from mic'ing the crank, and then you have your clearance?

 
Mic the crank. Lock it. Set the bore gauge to be slightly bigger than the mic. Place bor gauge in the Mic and while it is in the mic calibrate the dial to zero. Now place bore Gauge in the bore and subtract to get the difference, Unfortunatly the gauge will move backwards so count increments instead of looking at the numbers. You can flip some steps around to make the gauge read properly, but I don't because apparently I think backwards naturally.
That is basically how I used the bore gauge.

However, why go to the time and expense of a bore gauge?

Why not just mic the crank at the plastigauge, subtract the value from mic'ing the crank, and then you have your clearance?
There is always the chance that when you mic it with the plastigauge on there the plastic gives and you think you have more clearance than you do.

 
There is always the chance that when you mic it with the plastigauge on there the plastic gives and you think you have more clearance than you do.
I would agree, but the plastic is pretty tough after being squished to .0015.

 
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