Just saying "metric rings" leaves a lot out of the picture IMHO. There has been metric rings used in GM production engines for quite some time now- including the Gen 1 and 2 SBC. So to say 'metric rings' does not necessarily say anything is all that different that can't be handled by a competent machine shop (tension, materials, honing finish) other than the measurement system used to measure the rings. In the case of the SBC the top rings measure the same thickness for all intents and purposes, while the second rings are marginally thinner than the old fractional ring sets.
A 5/64" ring = 1.98mm. The LT1/4 Gen 2 engines and the later Gen 1 engines use a 2mm/1.5mm/4mm ring package. The second ring is akin to a 1/16" fractional ring. Radial tension may be less, but it does not HAVE to be so.
Last edited by cobalt327; 11-16-2012 at 02:40 PM.