Originally Posted By: Ducman
Originally Posted By: kschachn
What is it in the upper cylinder that needs lubing that isn't already being lubricated? No one ever answers that question, it's always determined that there isn't anything that is deficient.
At that point the discussion usually shifts to the other perceived benefits of a UCL, like fuel pump bearing lubrication. Until it is pointed out that the bearings are sealed and don't see the fuel nor the UCL.
Sometimes then a fuel economy increase is promoted. Until of course it is explained that such a small increase is unable to be observed in a real-world environment.
In the old days when leaded fuel ruled the earth, the upper cylinder lube was actually the lead in the fuel and provided a cushioning effect.
Obviously the lead also performed the function of increasing the octane rating in a cost effective manner as well.
The materials used on the Valve seats have changed with the introduction of unleaded fuel and also Aluminium heads. This largely negates the use of any added lubricant to protect the seat but a little extra help is good too.
These days of unleaded fuel it doesn't hurt to have a little help from some extra UCL. the Valve seats and Valve stems are directly lubed as a result.
Higher quality premium fuels are already formulated to varying degrees with UCL.
The area in the valve pocket also stays a little wet with lube and this helps to minimise a built up of Carbon deposits on the back of the valve and base of the Valve stems. It will literally wash off and not stick.
The benefits also extend to the combustion chambers where the Carbon stays a bit soft and tends to not build up on itself as much.
I have seen the benefits of it with my engines.
Some engine designs seem to benefit more from UCL in various ways.
It's a bit like greasing a baking dish before putting the cake mixture into it when baking a cake.
It's up to the individual to determine through experience whether it's of benefit to them personally to run an UCL or not.
I certainly do use it religiously, as the benefits of Carbon reduction in the valve pocket are evident regardless of the design.
+1
The hiting on the seat valves EVEN makes noise, so quick and hard it tends to recess and make wider clearances or tulip edge plastic deformation (does remmember of valve lapping Jobs?). Well if it makes sound of metal to metal, UCL wouldn't help?
Not that is absolutely necessity, but help to prevent wear and extend head life in hard use conditions, IMO. But 'm affraid that there's too much grandpas grocery grabber in here that say their engines are perfectly fine without UCL, but they're affraid to go beyond 4k rpms in their cars, for a reason. kikikih
