<VV> valve seats revisited

[judynrandy at comcast.net]

Yesterday was the Corvair Ranch's open house.  I went and had a blast.  Driving from Hopewell, Pa. to Gettysburg, Pa. involves trips over 3 rather steep South Central Pa. mountains.  So, as I drove along in my '63 ragtop 84/pg, I began to think of all the recent posts about mountains and valve seats. 

      I think I have this thing figured out.  As I ascended the steep side, I dropped my 'Vair down into low and slowly climbed the mountain at about 35-40 mph.  I do this because I read somewhere in one of our groups books a while back that that is the best way to climb a hill.  Drop down into the next lower gear when ascending as this greatly increases the airflow over the engine, thereby greatly increasing the cooling effect.  When first starting to climb the 

hill,  I  just put my hand down by the heater outlet and felt the "heat/air" coming from the heat duct actually change temperature.  I leave the heat/air on all the time in various configurations to keep the inside of the rocker panels warm and dry at all times.  The air temp quickly gets warmer then it's not long before it's HOT.  Then, when the grade gets steep enough you drop 'er into low.  Then with the increased airflow you can actually feel the temp slowly drop back down to moderately warm and it stays there until you crest the grade. 

      Now, going down the other side got me to thinking.  Someone posted that when descending a mountain in gear, " the charge of cool air hitting the seat helps to loosen it" or something to that effect.  As I descended the mountain in gear , I ran over and over in my mind the process of what exactly was taking place.  First, if you don't descend the mountain in gear, how else, exactly, are you supposed to do it?   Please don't say "brakes," as some mountains are tougher than that.  Besides, some are bad enough with the engine helping AND the brakes.  

      Anyway, I began to think, "Why does leaving the car in gear slow you down anyway?"  I ran the process over in my mind of what happens, and then I saw the light.  When going down the other side, you take your foot off the gas pedal and the butterfly valves in the carbs CLOSE .  So, basically, there is no air flow into the cylinders.  I don't think its a complete vacuum, but seeing how the holes and/or openings in and around them (butterflies) are very small and limited in size  not much happens.  As the intake valve opens,  the piston tries to accomplish an "intake" stroke only to be given the vacuum/suction from the other 2 cylinders doing the same thing.  I guess when the exhaust valves open, it breaks the "vacuum" suction and prevents it from being a true "vacuum" seal.  (Please be merciful to my physics explanation.  Hopefully, you get the idea of what i'm trying to describe . )  

The air temperature at the outlet goes from "moderately warm" slowly down to "warm", and depending on how big the mountain was, "luke warm".  But, I did notice that this is a fairly slow and gradual process. 

      So, for my 2 cents worth, I believe this theory works well as I haven't  lost a valve seat yet!  Theory confirmed!  Take that, "Mythbusters" !!!! 



Randy (Cap'n) Hook 

'63 ragtop 84/pg 

'65 monza 4dr. 110/pg