Posted by Polar Pilot on October 12, 2002 at 13:29:07:
In Reply to: I have a question about heads or valves.. something like that posted by Seth Denney on October 12, 2002 at 00:43:37:
The theory is that with an open pipe cold air will hit the hot valve at shut down and possibly warp the valve because of the unequal cooling on the edges of the valve.
With the drop in the header pipe on the Savage there is realtively little chance that this could happen because the hot air off the engine is trapped between the exhaust port and the flat section of the exhaust pipe. The hot exhaust is trapped in the upper section of the pipe because it tries to rise not fall inside the pipe and is lifted back to the top of the exhaust header not to the bottom and the open pipe.
Carb settings of course also have a big factor to play in this - a much greater role than cold air rushing up the pipe vis-a-vis valves warping.
OF much more serious concern is the impact on your hearing and the relation with your neighbours. But those are personal choices and ones which you will make regardless.
Keep the rubber side down
Polar Pilot