Measuring bores

[Guest]

I need to measure my bores to determine if they can be touched up, or if I need major work here too. I talked to the owner of the machine shop, and told him that I measured my pistons, on the rods and they are in spec. I want the shop to measure the bores because I don't have the tools (I could get telescoping gauges, but I worry about keeping everything square to get an accurate measurement). Anyway The owner said "No problem". Now I am dealing with his machinist and he wants me to bring him the pistons so he can measure and inspect them. I am a machinist myself. I use a caliper all the time. I can calculate clearance if he measures my bore. Is this a bad idea? Am I missing something? Is there a way that I can get a good measurement on my bores myself with a telescoping gauge and my caliper?

[oldpara]

Snap gauges are OK for ID's but it takes technique, a certain finesse to use them consistently. Try to get yourself a set of "inside mikes", or just let the machine shop mike them.

[Nessism]

Snap gauges suck for that kind of work. I tried using them and it was very difficult. A bore gauge is the way to go since it will note taper and out of round very easily.

BTW, it's easy to remove the pistons.

[cowboyup3371]

Honestly, I think if he's any kind of a good machinest too he'd rather KNOW he's giving you the right info and not just guessing. What would it hurt to have him do it?

[BlackStar]

I'd let him measure the pistons. If I were him I would want to measure the pistons too, for the reasons stated above.
Calipers are not the best tool for measuring pistons, Use the proper size micrometer.
And yes snap gauges are a PITA to get repeatable measurements, takes me forever (because I don't do it for a living).

I use one of these for bores. Requires the proper size mike or gauge rings to set it up.

http://www.use-enco.com/CGI/INSRIT?PMAKA=890-9981&PMPXNO=5507081&PARTPG=INLMK3

[Big Jay]

You don't want to measure pistons with a caliper. You should use a micrometer.

I agree with your machinist. When we are setting up clearances we always insist in measuring the pistons our selves.

For the bores, we use a dial bore gage that reads in tenths (.0001") We also set the gage with the same mic we measure the pistons with.

[dansofield550]

calipers are given to apprentice's for roughing out work (here that is) let the guy do his job a three pronged bore gauge is the only thing to measure a bore with and micrometre for the pistons,

calipers for roughing and stirring tea when the spoons gone walkies

[snyderman]

Thanks for all the input! I am pulling my pistions to give to my machinist.