During break in, there are two main parts that need time to seat. The first is the camshaft (running the engine about 1500 RPM for 20 minutes does that and the reason for the higher RPM is to make sure the lifters rotate) and the piston rings. The card that came with the piston rings in the engine for my 68 American (they are Sealed Power rings -- hardly anything exotic) said that if the cylinders are finished a certain way, the rings will seat in the first 10-15 minutes of run time. If they don't, you have to refinish the cylinders and replace the rings. I know that Mobil One has said that you can use it's oil for break in and it will not interfere with the process but as was previously pointed out, it doesn't make sense economically. Matt Brien Tourville wrote: > they might be pre-broken-in. it's possible today to make engines that > require little break-in time, and they might be running them on test > stands before installing them in cars; lincoln did this back in the > early '60s - 2h on -every- 430, incl. 30m at full throttle. those > cars would regularly go 250000mi without touching the engihe. even > more remarkable considering the inattention they likely got and the > oils of the day. > > " Personally, I believe it makes some economic sense to use conventional > " for the first couple of changes, when you're changing it on really short > " intervals, but if you've money to burn, I see no reason you couldn't use > " synthetic from day one. > > i've heard that synthetics are too slippery to allow proper break-in > wear. > ________________________________________________________________________ > Andrew Hay the genius nature > internet rambler is to see what all have seen > adh@xxxxxxxxxxxxxxxxx and think what none thought > > > > ===.=== > > > when I built the Race Engine for a BMW flat twin - > under tutelage from Udo Gietl - BMW Importer Butler & Smith - > head of Service & 'BMW RoadRace' > > [ Daytona, Bikes Winning 1974,5,6,7 ] > > the drill is dry cylinder walls > with oil smeared on the piston skirts: > > fire engine / maintain 2,500 RPM for one minute > which cuts the working surfaces of ring pak to > cylinder walls. > > the results were excellent - both cylinders > measured at the top of their compression range > and maintained for years being beaten regularly. > > Synthetic Oil back then had just hit the market - > I stayed with Castrol GT for break in - as recommended. > > > > > > > -- mhaas@xxxxxxx Cincinnati, OH http://www.mattsoldcars.com 1967 Rambler American wagon 1968 Rambler American sedan ================================================================= According to a February 2003 survey of Internet holdouts released by UCLA's Center for Communication Policy, people cite not having a computer as the No. 1 reason they won't go online. _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list