Even with short, open headers, there is plenty of hot cylinder head that would heat any air on shutdown.
I'd look into using an H-pipe setup- provided your 86' SS has a healthy mill in it, a H-pipe setup with no mufflers and with tails out the back or with good sounding mufflers will really sound great. Now my left cat is smoking up the entire car. The theory is that upon shutdown, cold air can reach the valves and warp them especially if they are open unseated from the head.
Heat distributions show the hottest part of the stem in an area just slightly above the head and just below the guide where some valves in an effort to improve exhaust flow, are actually necked down just before flaring out for the tulip head -- exactly where stem temps are highest, exacerbating the issue from both a heat transfer and tensile strength stand point.
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Oct 1998 Location: Click Here to join Eng-Tips and talk with other members! I put about 2000 miles on my 86 Monte with a 350 in it, with open headers.
If the engine is properly tuned and not abused the engine will last without burnt or wrapped valve's but low on power. One counterpoint to this theory is that losing an exhaust causes the engine to run lean, and this is what actually causes damage to the exhaust valves. The explanation that I was given by the bike shop was that the decreased back-pressure of the more free-flowing exhaust led to a leaning-out of the engine which in turn led to the damaged exhaust valves.
Honestly I think its kind of bs.
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My headers have 3 inch collectors. The one thing to keep in mind while youre driving there is that there is a lot of sound ordinances around town and you can get a ticket for making too much noise with your vehicle.
Any engineer should be able to see through that. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. May 2001 Location: Excellent 4: I broke a few cranks, dropped a few valves, blew out a combustion chamber, broke a dudgeon pin and cracked a few crankcases, but never burnt a valve no matter what exhaust or what damage to the exhaust.
An engine with short headers will run leaner than if it had longer exhaust tubes due to sucking back fresh air diluting the mixture. Digg this Thread! My real point is irrespective of brand names or exhaust system design, if the engine is tuned and maintained correctly and you use quality parts and specify and install them correctly, you don't burn valves.
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