Hi, i am building my bottom with wiseco 78,5 (78,49mm) pistons and i get my cilinders honed to 78,56mm as requested on wiseco instruction (0.0028/0.0030" gap)...
Now that i i am going to gap the rings i found the top ones to be in 0.017/0.018" range but the bottoms are on 0,026/0,027" range, it seems to high to me...

any idea?

 

Don't wiseco use multiplication factors?

Your bore * 0.00xx = ring rap?





I think I ended up with .017" top gap and .019" bottom gap for my 84mm pistons. I'd have to dig up papers.

 

according to that table i should gap al least the top at 0.0216" and bottom at 0.0232"
but out of the box the bottom are 0.0256" so i think machine shop bored too much...

 

I had a thread on this last week. On my 84.5mm wisecos, I ended up picking the closest feeler gauge width that was above my targeted use, so I ended up with roughly .017 top and .019 bottom, which puts me roughly halfway between turbo and oval track.

Are you sure that your rings were perfectly square in the bore when you measured? Use a piston and make sure exactly the same amount of piston is pushed in all the way around the edge. If you're off even slightly you get huge errors in measurement. Also make sure the ends of the ring are butted together (ie, perfectly aligned). If there is a slight misalignment it can increase the measured gap.

edit: here is previous thread https://www.miataturbo.net/engine-pe...oddness-87267/

 

Yes I used a piston to set ring in the bore, and i measured different bottom rings at different height inside the cilinder...


Maybe bad/wrong new rings? I took them as a complete kit with pistons and they say 7850XX on the package...