Posted by oscar on Wednesday, February 19, 2003 at 7:55PM :
In Reply to: Piston Rings posted by Matt Wilson on Wednesday, February 19, 2003 at 7:07PM :
I'd clean the bore , piston, rod,crank and everything really well and carefully reinstall.
Either rings will do well. The moly rings should last longer than the cast but either will do ok.
You can lightly rehone or not. The rings will seat - just run the engine gently for the first 3000 miles - the first 500 miles are the most important - Change the oil after 500 miles. Having the parts & bore clean is VERY important.
I prefer to grease the bears and oil the piston and cylinder heavily. You can remove the spark plugs and spin the engine with the starter to get the oil moving around the engine prior to the first startup.
You can use a light oil (wd40) to install the piston and then pour in about 1 cup of 5/30 to lube the rings as you install the other pistons. I like to put in Rislone with just enough that the oil does not get all over everything as I rotate the engine during the install process. I remove the spark plugs before the first crankover in case I've put to much oil in a cylinder. Excess oil just comes up the spark plug hole where I keep a rag to soak up the excess.
Not oiling the piston and bore makes the rings seal more quickly. They will not last as long and you risk scoring the cylinders and piston plus there is a lot of wear and metal shaving generated all at once. Not something I like
Oiling the pistons cylinder and rings slows down the break-in process but that is the key to getting it to last a long time.
I like to break the engine SLOOOOWLY and gently. The break in cycle on the flatheads could take a couple of months. The difference between the new engines and the rebuilds is the accurary and close tolerances. The new engines have clearences in the 1/10000 - 2/10000 range. The Tolerances on the flathead were in the 5/10000 - 2/1000. The machine tools today are just better. The engines in todays vehicles are alot better before they are ever started.
The flathead is a great engine. Just treat it with respect and tlc & it will return good service.
Good luck
Oscar
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