Out of round liners

My 8n liners are out of round by as much as ,010 or more. I know this happens from normal wear. Does worn crank bearings have any thing to do with that much out of round? My liners have a little lip on the inside top. Or is the lip just where the piston stops? Gotta buy better calipers.
Thanks

(quoted from post at 20:49:00 09/22/22) My 8n liners are out of round by as much as ,010 or more. I know this happens from normal wear. Does worn crank bearings have any thing to do with that much out of round? My liners have a little lip on the inside top. Or is the lip just where the piston stops? Gotta buy better calipers.
Thanks

Click to expand...

Calipers have their place but IMOH, measuring bores is not one of them. The lip is wear, time to replace the sleeves.

Your money, Your Tractor...
All the best with obtaining accurate readings.....
Bob. Retired Power Engineer..

I concur RG, best to use a precision dial bore gage with readings in tenths. You can also check for taper as well. A good, qualified machine shop will have the correct gages and tools for the job. This is one reason why FORD switched from steel cylinder sleeves to cast iron in 1950. They knew there was a problem with steel from FoMoCo on day one - why did they need to ID steel sleeves with a STAR symbol on the engine block serial number??? BTW & FWIW, calipers and mics will not pass a Gage R&R Study. That's Gage Repeatability & Reproducibility for one technical method used in precision measuring, for those unfamiliar.

Tim Daley(MI)

(quoted from post at 06:50:41 09/23/22) BTW & FWIW, calipers and mics will not pass a Gage R&R Study. That's Gage Repeatability & Reproducibility for one technical method used in precision measuring, for those unfamiliar.

Tim Daley(MI)

Click to expand...

Really? FWIW Gage R&R is simply a metric. There is no inherent pass or fail value for that metric.. The suitability of an instrument has to be evaluated in the context of the process in which it is being used. If I am sawing framing for a house the gage R&R for my 25' Harbor Freight tape measure is more than adequate in that process.

Gage R&R of micrometers and to a lesser degree calipers is more than adequate for ordinary engine building. Your bore gage is a comparative instrument and is commonly zeroed using a micrometer as the standard. So in that context we have two instruments involved and Gage R&R variations compounded by the zeroing process followed by the comparison process.

None of this is particularly meaningful or helpful in the context of the original question.

TOH

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Reminds me of the old lecture from Tech school: Precision vs Accuracy.

The lip is a ridge where the rinds don't ride. Almost all engines with any mileage will have one. My
Toyota truck with 350,000 miles had a neglible ridge when I opened it for a valve job a few years ago to my
surprise.

(quoted from post at 09:19:38 09/23/22) The lip is a ridge where the rinds don't ride. Almost all engines with any mileage will have one. My
Toyota truck with 350,000 miles had a neglible ridge when I opened it for a valve job a few years ago to my
surprise.

Click to expand...

s "neglible" a term of "precision" or "accuracy"?

You can be "accurate" but not "precise", and vice versa.

It's best to be accurate AND precise.

To OP. The "ridge" forms at limit of travel (TDC) of the piston rings.

IMHO a good snap gauge and quality micrometer (measures tenths/ 0.0001") are what is needed. Besides "out of round" on cylinder, check pistons for clearance and out of round. 0.010" is way out of round.

If you were doing just a "ring job", you would use a ridge reamer to remove the ridge then lightly hone the cylinders.

(quoted from post at 09:18:44 09/23/22)
You can be "accurate" but not "precise", and vice versa.

It's best to be accurate AND precise.

To OP. The "ridge" forms at limit of travel (TDC) of the piston rings.

IMHO a good snap gauge and quality micrometer (measures tenths/ 0.0001") are what is needed. Besides "out of round" on cylinder, check pistons for clearance and out of round. 0.010" is way out of round.

If you were doing just a "ring job", you would use a ridge reamer to remove the ridge then lightly hone the cylinders.

Click to expand...

nap gauge is a good idea for someone doing it themselves. Rigging up with a set of Fowlers isn't necessary if your not on someone else's time clock.

(quoted from post at 11:38:10 09/25/22)

(quoted from post at 09:18:44 09/23/22)
You can be "accurate" but not "precise", and vice versa.

It's best to be accurate AND precise.

To OP. The "ridge" forms at limit of travel (TDC) of the piston rings.

IMHO a good snap gauge and quality micrometer (measures tenths/ 0.0001") are what is needed. Besides "out of round" on cylinder, check pistons for clearance and out of round. 0.010" is way out of round.

If you were doing just a "ring job", you would use a ridge reamer to remove the ridge then lightly hone the cylinders.

Click to expand...

nap gauge is a good idea for someone doing it themselves. Rigging up with a set of Fowlers isn't necessary if your not on someone else's time clock.

Click to expand...

The guys in the metrology department are pulling their hair out :roll:

[b:00ddbd02e1]All About Snap Gauges - Definition, Sizes, and Uses
[/b:00ddbd02e1]

[size=18:00ddbd02e1][/size:00ddbd02e1]

Snap gauges, sometimes called gap gauges, are metrology tools that are used to gage the diameter or thickness of a part or material. These tools are versatile and are designed to provide a quick go/no-go decision on cylinders, shafts, grooves, and other similar parts and features in machining operations. [b:00ddbd02e1][u:00ddbd02e1][color=red:00ddbd02e1]Functionally, snap gauges perform assessments on the outside diameters of parts[/color:00ddbd02e1][/u:00ddbd02e1][/b:00ddbd02e1], similar to other tools and measurement instruments such as ring gauges and thickness gauges. Snap gauges can be used for checking dimensions on both cylindrical and non-cylindrical parts whereas ring gauges are for cylindrical parts only.

Replace the pistons and liners,check the rod and main
journals for size and out of round.