When I originally made the magnet suggestion last Monday, I wasn't sure if it would work. The stainless that I've had the chance to hit with a magnet haven't been magnetic, so I figured it was worth a shot. The last metallurgy class I took was almost 30 years ago, and my memory is showing signs of fading. (grin)
The idea for stainless exhaust valves came from a conversation I had with the engine shop doing my Spitfire 1500 rebuild in 2002. They suggested stainless exhaust valves as part of making the engine happy with no lead fuel. Since Spitbits offers stainless valves, I bought 4 and let the engine guys do their thing. As several previous posts have pointed out, given the low mileage most Triumphs get, making a special point of reworking the head probably isn't needed. BillG Newalla, OK -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Porter Sent: Wednesday, August 06, 2008 2:31 PM To: Steve Beswick Cc: [email protected] Subject: Re: [Spits] Stainless test Steve Beswick wrote: > To those who have recommended using a magnet to test valves:Stainless Steel > is magnetic. How do you think magnetic knife bars work? > Umm. Sort of. Austenitic stainless steels are not magnetic in their annealed form, but become weakly magnetic with working, but not as strongly magnetic as ferritic stainlesses or other carbon steel. The more an austenitic stainless is worked, the more magnetic it becomes. So, it's true that a magnetic test won't identify a stainless valve from a carbon steel valve. As for the original question, I don't think a stainless valve is necessarily a mandatory item for unleaded operation, and depending upon the stainless alloy, might not actually be the best choice, as some stainlesses are not as hard as better carbon steel valves, and the valve face may deform around the valve seat over time. In any event, simply assuming that "stainless" is better is not necessarily true. Any valve with Stellite hard facing is probably just as suitable. Cheers. _______________________________________________ Support Team.Net http://www.team.net/donate.html [email protected] http://autox.team.net/mailman/listinfo/spitfires http://www.team.net/archive
