Alpine951

I looked on a few websites for oem 951 rings and there are different sizes. Why is that? My car has group 1 pistons. Is the reason for different ring sizes because of the different tolerance groups. Sounds like a dumb question but I want to make sure. I still have to check the piston widths to make sure the clearance is OK. Does piston/cylinder clearance also affect which rings are used?

cruise98

the rings are for the different bore sizes, not tolerance groups. Tolerance groups are within each bore size.

Alpine951

So if group 1 bores are 100.01mm and my bores are good then I need 100.01 rings?

Ski

If you have group 1 piston, your cylinder bore should be 100.010 +/- .005. Your pistons, measuring from the top, down 61mm or 2.4" (about 5-7mm from the bottom) should give you 99.990 +/- .005mm. With the ring gap tolerance being .20 - .45, you should be fine with a standard ring set.

Alpine951

Bret,

What is considered standard. The attached link is what Paragon shows. its ays standars and 100mm. Is that what is standard on my car no matter if the bore is 100.0mm (group 0) or 100.01 (group 1)?

http://www.paragon-products.com/prod...103.901.02.htm



John

Ski

I don't know if they make the ring set for the different tolerance groups to tell you the truth, since the difference in piston diameter is only .020 between the piston sizes (99.980 - 99.990 - 100.000). The last engine that we built, standard bore (just hit the cylinders with the finishing stones, oil, and alusil paste) I used a standard ring set and they were tight. We set the gap at .25 on the top two rings and .50 on the bottom, I'd have to go back and look at the sheet to be sure.