Posted by Jack Smith on March 22, 1999 at 18:21:43:
In Reply to: Piston Size posted by John Moschinger on March 22, 1999 at 16:48:34:
John,
Whoa boy...you're getting way ahead of yourself. Let's take it a point at a time. You only break glaze and use standard size rings if there is no appreciable ridge present. Since you already know there IS one, read on....
OK, you have a ridge above the piston...you won't be using standard sized rings or pistons. Get yourself a ridge reamer and pull the pistons out, and THEN mike the bore using a proper bore mike, and see which next available oversize is called for. DON'T attempt to reassemble the engine with standard pistons or rings if you have a measurable ridge. RIngsa don't just wear on their diameter, but also on their height or thickness. They slide in and out of the groove under tremendous loading. If you don't clean things up properly, the new standard size rings will strike the old ridge repeatedly until something breaks. You're better off letting your machine shop make the size determination, as they know what allowances are needed for their particular type of boring bar. (the flathead blocks are high silicon iron, and they don't ridge easily, only after considerable wear. It's not unheard of to go through two sets of standard sized rings before a ridge forms) Next, if the top end is that worn, you'll be needing to look at the bearings and other wear parts. This is not a cheap engine to rebuild, so try not to cut corners. At any rate, rings and bearings in standard size and oversizes are widely available almost overnight anywhere in the US. Pull it apart and go see your machine shop.
Have fun!
Regards,
Jack