How Do I Read A Dial Caliper ? ? ?

[SCHOONER]

HI GUYS

HERE I AM AGAIN. YOU GUYS ARE REALLY TEACHING ME THINGS ABOUT AN ENGINE I NEVER KNEW AND I THANK YOU ALL FOR YOUR EXPERIENCES.

SO HERE WE GO:

I TOOK A COMPRESSION ON MY ENGINE AND 3 OF THE CYLINDERS WERE READING 105,102, AND 110 AND THAT AIN'T GOOD.
SO I FIGURE WITH ALL YOU HELP THAT I GOT TO GET MY '66 'STANG WITH A 289cid TO THE AUTO MECHINE SHOP TO HAVE THE CYLINDERS OPENED-UP TO THE LEAST AMOUNT OF GRINDING.

FROM WHAT I UNDDERSTAND (and that ain't much ) I SHOULD NOT GO TO: 60 THOUSANDTHS. ANYTHING UNDER THAT IS GOOD ~ RIGHT GUYS

NOW I GO BUY A DIAL CALIPER TO MEASURE HOW FAR GONE ARE THE CYLINDER COMPARTMENTS. I FELT ALL THE WALLS AND THEY FEEL PRETTY DARN S M O O T H. BUT THAN AGAIN WHAT THE HECK DO I KNOW

I PUT THE DIAL CALIPER INSIDE ALL THE CYLINDERS AND OPENNED UP THE JAWS OF THE CALIPER AS MUCH AS I COULD TO GET A GOOD READING AND ON ALL OF THEM IT WAS: (4) FOUR INCHES WIDE.

NOW IT REALLY GETS GOOD I DON'T KNOW HOW TO READ WHAT'S GOIN' ON WITH THE BLACK and RED DIALS ON THE ROUND DIAL.

WHAT I CAN SEE IS THIS ~
THE BLACK INDICATOR IS ON: 97
THE RED INDICATOR IS ON: ONE NOTCH UP FROM THE .5

I SURE HOPE THAT HELPS YOU GUYS TO HELP ME WITH THE READING AND WHAT THE HECK THEY MEAN

I'M TAKIN' A GUESS THAT THE 4in. WIDE READING I GOT IS A GOOD INDICATION THAT EVERYTHING IS GOOD. AND THE MACHINIST HAS ENOUGH METAL TO OPEN-UP THE CYLINDERS, (GOD WILLING )
BUT THAN AGAIN GUYS I'M IN YOUR HANDS

THANK YOU ALL.
GOD BLESS YOU AND YOUR FAMILIES THIS CHRISTMAS SEASON.

SCHOONER

[Rev]

The 4.000" measurement that you are getting accross the top of the cylinder means that the block has not been previously overbored. This doesn't mean that there's not cylnider wear further down the bore where the rings scrape against the cylinder wall. If you check with your finger tips, you will probably feel a ridge at the top of the cylinder wall. That's from the wear created by the piston rings against the cylinder wall.

Generally speaking, a .030" over bore will make the cylinder bore smooth and true. The machinists that I know don't recommend boring more than that on the thin wall casting of the small block Ford engine.

My dial caliper uses a regular scale for the first .100 past the inch scale. The dial portion measures additional thousanths of an inch. If I had a 4.0 on the regular scale and the dial read a 30 that would make a measurement of 4.030" which is what my original 289 block was bored when the rebuild was done.

Your machinist will evaluate the block to make sure he has something good to work with. He will check the cylinder bores for enough to make a good true cylinder. He will also check for cracks and other problems before he does all that work.

Rev

[SCHOONER]

Hi Rev

Thanks for your clear explaination on dial caliper readings.
I understood it all.

Now, what I'd like to do is get an inside micrometer so I can do the readings myself.

The inside of my cylinders are very smooth, as far as any cracks I don't know about that

Think I can locate 'em myself

Rev you know in this world lots of people like to get-over on others who don't know too much about rebuilding an engine (ME)

So I'd like to check the bore myself and see if the machine shop is trying to get over on me.

What do you think

Thanks Rev
GOD bless and Happy New Yr.

Schooner

[Rev]

The problem as I see it is that you might spend a lot of $$$ on expensive specialized tools that may not be used but once or twice. I would get recommendations from local gearheads for a machine shop that is honest and capable of the kind of work that you want. You may want advice as well as skilled engine building. There is quite a difference in the way a high performance engine (more time and $$$) and a run-of-the-mill rebuild are done. E.g., balancing, proper tolerances, heads, porting, cam, valve train, rods, pistons, fasteners, etc,etc. I wouln't use a shop that I didn't have a lot of confidence in. This is just my take on it.

Rev

[Jeff Chambers]

You can't accurately measure cylinder distortion with a dial caliper. You need a bore gauge, and they're some serious $$$. Even at that it takes some experience in reading a bore gauge correctly. You'll be time and money ahead to just take it to a qualified machine shop and have them take the measurements. Ask them to show the measurements to you and I'm sure they'll oblige.

[Rev]

Jeff, if you get bored, you can always line your tow truck up against those stock Hondas and Miatas that always seem to be at the track, LOL.

Rev