[AD removed for archives] ------------------------------------------------------------------- Erase wrinkles without painful injections with Nexiderm SP. Nexiderm SP is clinically proven to reduce wrinkles by 68% Click here to get your 30-day free supply. caadAclbOyW3Na/Nexiderm ------------------------------------------------------------------- Yes, for a 4.000" bore the piston is slightly less than the bore to make space for the rings, which do press against the cylinder wall. They need to press against the wall to ensure you have compression. Which is is why it is extremely important the cylinder walls get oiled otherwise the rings will score the cylinder walls and destroy themselves. And why the ends of the rings have a small space between them - to provide room for expansion / contraction whille keeping the ring pressed against the cylinder wall. When you bore the engine .030" the pistons are also increased in diameter by .030". That way the piston is still slightly less in diameter than the bore to make space for the rings. If, say, there is a .0025" gap between a standard piston and the cylinder wall in a standard bore, the piston diameter must be increased by the same amount as the bore or the piston-to-cylinder wall gap will be incorrect. In this scenario, a 4.000" bore takes a piston that is really 3.9975" in diameter. If you increase the bore to 4.030", the piston must be increased .030" to 4.02975" to maintain that .0025" gap. The pistons have compressions rings and oil rings. It is important the oil rings be installed right way up, by the way. They act as a dam to prevent oil from getting into the combustion chamber. On some oil rings if they are installed upsidedown the oil will be pushed up into the cumbustion chamber. Bill Vancouver, BC ----- Original Message ----- From: "Robert neal zimmerman" <northwestweirdo@xxxxxxxxxxx> To: <1962to1965mopars@xxxxxxxxxx> Sent: Saturday, June 04, 2005 2:52 AM Subject: Re: a really BORING question i appreciate the responses but I think u guys are missing my point. Let me put it another way- There cant be zero tolerance in the cylinder, there has to be a clearance. The hole cant measure 4.030 AND the piston as well, nothing could move, there has to be a slip, Where is the slip??? Either the piston has to be slightly LESS than the 4.030 of the hole OR the hole must be slightly MORE than the 4.030 of the piston. Is that more clear? Neal Zimmerman, Eugene oregon [AD removed for archives] ------------------------------------------------------------------- Buy Stocks and Index Funds for just $4 No Account or Investment Minimums and No Inactivity Fees Automatically invest weekly or monthly and build your future. caadAcmbOyW3Nf/Sharebuilder ------------------------------------------------------------------- ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html. bOyW3N.