This is the first time I've used a dial bore gage so Rob Parelli of Tork Teknology lent me his Sunnen dial bore gage and vernier micrometer to check the cylinder bores of my ’87 Ford F-250's (Project 300) International 7.3L IDI diesel engine.

 First off I needed to figure out what size my cylinder bores were supposed to be for the International 7.3L IDI non turbo block. The machine shop said it was supposed to be 4.1100-inches (+ or - .0005). 

1. Setting the vernier micrometer: This micrometer can measure down to .0001-inch or (one ten thousandth of an inch). This particular one measures between 4 and 5 inches. This one inch distance is broken down into ten sections on the spindle. This number is the first one to the right or .1, .2, .3., .4,......

So we get:

4.1

Then we notice between each whole number there is 4 sections or 4 quarters.

So looking at our measurement we get:

.000

Because the spindle does not quite make it to the first quarter mark.

Now look at the sleeve broken into 25 sections. Our measurement is at 10 or .010

So we get:

4.1+.000+.010= 4.110

Now notice the lines directly above the scale we've been looking at. Check and see which one lines up to get your last digit.

Ours says 0 so we now have: 4.1100-inches on our micrometer

Now find an extra set of hands to set the dial bore gage with the measurement on the micrometer.

We downloaded the instructions from Sunnen and they said diameters between 3.875 and 4.250 use the gage point number 6 as shown in the picture. The point has a set nut that you tighten once you get the point screwed into the proper depth.

The big dial on the dial bore gage spun 1/4 turn when we put the micrometer between the two measuring points. We loosened the set screw on the dial and zeroed it out.

Now with our dial bore gage set to 4.1100-inches we inserted it into the bore.

As we moved the dial bore gage into different positions around the different cylinders to get an idea of there shape we saw all our cylinders were with in specification...except one...#7....the back one on the passenger side.

Looking at the dial bore gage end opposite of the dial you have the point we screwed in on one side and two rollers and a point on the other. The two outer rollers keep the gage centered in the bore. As you rock the handle you see a spike on the dial. This happens when the two points are horizontal to the block giving you the exact diameter to the ten thousandth of an inch. Each section on the dial equals .0001-inch.

Our #7 bore measured 0 on the bottom but .0008 at the top. This is due to us taking a three stone hone to it for too long in order to get the rust spots out. Looks like we went to far trying to clean it up.

We'll send this block to ARP so it can get measured for studs and bolts. We have a new block lined up and its better because its a 7.3L International turbo block.

We could re-sleeve this block but that would cost too much...good thing these IDI motors aren't too valuable...to most people.   

Prior blog about getting the heads and crankshaft from the machine shop.