Regrettable Engine strip down !!!! I think " Follow up". But it's not over.

Quote" Ok Kawboy, see where you are coming from . This maybe the instrument used, the new caliper is 100% I've tested it with gauge plates. But it could be the internal bore gauge. This is the T type with the spring loaded arm, that you lock at the specific diameter then measure out of the bore. ?" 

I think I know why the numbers are "Goofy" It's a technique issue when using the manual bore gauges. I know it would seem natural to insert the bore gauge into the cylinder and then lock it up, remove it and measure, but that's  not how to use them. you need to lock them lightly at a diameter slightly larger than the bore to be measured , then roll the bore gauge through the cylinder which causes the bore gauge to collapse down to the bore being measured. The bore gauge will find the largest diameter and hold that position until you measure with an outside micrometer or if all you have is a vernier. Typically, what I do is insert the spring loaded bore gauge into the cylinder and hold the handle at a slight angle to the centerline of the bore and lock the handle lightly. Then roll the handle up vertical and through the vertical, then remove and measure.

As for the rings- it sounds like you have a set of keystone profile rings in there. I'm not up on this particular style of ring, but AI suggest it's primarily used on diesel piston s to break up carbon deposits. How you ended up with these rings is beyond me. See pic??

 

Kawboy, this makes so much sense. The bore measuring tool probably my fault for incorrect use !  can't wait to use it in the correct manner.
OK down to the rings ? i suppose when you open up a engine that's not been owned from new, don't expect it to be as it should !!!
Top ring on #1 looks to be a mixture of internally stepped ring and the full keystone ring. looks so wrong in every way.  Just checked out #6 Top ring, looks more normal but ring end gaps failed miserably . Piston groove well within limit. 

Glad to help out. I have a dial bore gauge and they are a treat to work with. With my background at the plant, our tooling in the machine shop introduced me to tools like this and once you use them, you can't help but get one for yourself.
I was watching a Youtube video on Nicom (Nickel Composite) plating cylinders and diamond honing cylinders and the newer Rottler honing machines actually measure the tapers / variances in the bores by the pressure on the honing stones and map out the differences on a screen. then as you hone, you can see the variances disappear. REALLY COOL !! Mind you a well outfitted Rottler with a complete set of diamond honing stones can run you up to $400,000 USD. Ouch !!  Makes me want to go get a job in a well outfitted machine shop. To be honest I don't know of anywhere that has tooling like this. Maybe NASCAR related shops would have them. Facinating watching the NiCOm process. My 1985 Porsche 928 had NiCom cylinders.

Looking forward to hearing what you find now that you're focused on the likely problem. Scotch went to the nth degree to find rings for one of his engines and ended up buying rings from IMD. I had a conversation with Andrew Wright at IMD regarding rings . I told him who I was and he offered up a discount code for our members which is 15% off. The code is " 1300club " if you're interested.

Link to IMD for pistons or rings

KB

Hi Kawboy, $400,000 Ouch ! I love precision engineering, but its not cheap.
IMD I used them for new pistons and rings on my Z1R.
Thanks for that, 15% discount very useful indeed. So are they in the US as well as the UK ? I do know they are about 100 miles north from where I'm situated .
Well back to the measuring for now .

Only in the UK as far as I know. Good people. Only hitch for us is the import duties and the process to clear them can delay shipping by 2-3 weeks.

Scotch went to the nth degree to find rings for one of his engines and ended up buying rings from IMD.

My '80, 5 yrs ago and the recent '79 rebuild both have IMD rings.  No regrets, so worth the $$$ !