ix1037@sdccs6.UUCP (Christopher Latham) (07/05/84)
My father being the owner of cars made in the days before all cars were required to use unleaded gas is somewhat concerned with the upcoming demise of leaded gas. It could mean a large problem for the valves in his engines. What he has been wondering is what the difference is between the valves on old cars which require leaded gas for valve life to be reasonable and the new cars which run on unleaded gas. Just what have the auto makers changed to give the same life to engines running on unleaded gas. Replies by mail would be reatly appreciated. Christopher Latham U.C.San Diego Dept. of Applied Mechanics and Engineering Sciences ..sdcsvax!sdccs6!ix1037
wookie@alice.UUCP (07/10/84)
The newer engines use harder valve seat material to prevent wear which used to be prevented by the lead in the fuel. One way to fix the problem is to get heads from a newer engine of the same type which will have the hard seats. A side benefit of this is often a reduction in compression ratio which will lessen detonation in the old high compression engines.. You could wait until the engine needs a valve job and either have hard seats installed in the old heads or go to the junk yard, pick up a newer set of heads and have them rebuilt instead. It's interesting that back when they proposed putting lead in the gas in the first place, one of the big controversies was how it would affect valve life and leave big deposits on the valves. So here we are going the other way! Keith Bauer White Tiger Racing
haapanen@watdcsu.UUCP (Tom Haapanen [DCS]) (07/11/84)
Says Keith Baker: > The newer engines use harder valve seat material to prevent > wear which used to be prevented by the lead in the fuel. One > way to fix the problem is to get heads from a newer engine of > the same type which will have the hard seats. A side benefit > of this is often a reduction in compression ratio which will > lessen detonation in the old high compression engines.. You > could wait until the engine needs a valve job and either have > hard seats installed in the old heads or go to the junk yard, > pick up a newer set of heads and have them rebuilt instead. A reduction in comnpression ratio (from the head swap) will: (1) Lower the performance of the car and/or (2) Increase the fuel consumption due to the decrease in the volumetric efficiency of the engine. Also, how are you supposed to find new heads for cars that were never available in unleaded gas-only models? There is no way I could find such heads for my '72 Bug around here at least (even though they may have been available in California). Tom "flat-six fanatic" Haapanen {allegra,decvax}!watmath!watdcsu!haapanen U. of Waterloo (519)744-2468