The rectifier usually just needs to be cleaned. The factory says every
10,000 miles. It may need some other things, which we will go into later, but first, how to clean it. First the entire unit is removed from the manifold. There are four long
bolts that go through the unit, remove the four nuts and slide the unit out
of the exhaust manifold. The factory used brass nuts so the heat would not
rust the nuts making it easy to remove. Brass or stainless steel would
work. If you can't get either, use high temp anti seize compound. First remove the domed portion that fits inside the manifold by removing the ten
small screws. Save the copper gasket as they are hard to find and it can be
reused. Once off, you will see the inner cup. The inner large tube marked
as outlet "0" in this article has two flats on it. Use a wrench that fits it and
unscrew it. The little tapered pipe next to it has a hex base and can be removed with a socket. Clean all the stuff beneath the cup you just removed
with carb cleaner and by scraping. Now you will see the bimetallic strip.
This strip bends when over heated thus allowing the oil to go back to the
engine. To adjust this valve, heat some oil to 225 degrees fahrenheit, and
pour it in the depression where the valve is. It should open. If it does not,
turn the screw located at the end clockwise until it opens. Do this quickly
before the oil cools. The above temperature was listed in Mr. Skinners patent. If the valves in the unit do not hold vacuum, the unit will not work.
To repair them, simply take a toothpick and insert some valve grinding compound into the valve and rotate it by hand. Check for good
vacuum. It is imperative that you wash all of the valve grinding compound
out, so that you can test it right, and so that the compound won't grind the
seat away. Also in the bottom portion, there is a check valve. It is nothing
more than a large ball bearing held in with a clip. If the ball bearing is pitted, or if its seat is pitted, the unit will not work. The clip can be removed
with a needle nose pliers, just squeeze the parallel wires together. Be careful, this thing can easily shoot across the room and be lost. Buy two ball
bearings of the same size. One you will epoxy a stick to. This one you will
coat with valve grinding compound and rotate back and forth until the seat
has no pits. Wash out the valve grinding compound and put in the new
ball. Now assemble and install. Make sure that the gaskets for the two
halves are good. Remember, we are working with a very low vacuum, the
smallest leak, and it won't work.
We drove Leo Walter's 70A from Chicago to Ohio and it didn't smoke
until we got to the meet lot. I took a wrench and turned the large bolt on
the vacuum line, may be one quarter of a turn, and the smoke stopped like
you had turned off a switch. I had the smallest of a vacuum leak, so I can't
stress this too much. Make sure all of the fittings are vacuum tight. When
the rectifier is working right, the Knight smokes little or not at all.