|
Why does valve train weight matter? The heavier the combined valve train weight
is, the stronger the springs must be, with a given cam profile, to achieve a
given RPM. The more spring load there
is, the faster the cam lobes and lifters are worn. So keep the valve train light.
Flathead V-8 lifters may be adjustable or fixed. Some of the weights I’ve seen are
45-52 grams. Hollow
stock non-adjustable lifter. There are
at least three types of these.
83 grams. Production
hollow adjustable lifter.
103 grams. Modern
Johnston
adjustable, solid, with oblong lots on the sides.
118 grams. TRW
made adjustable lifters for Ford.
143 grams. So far
the heaviest I’ve found; a 1953 part
number solid lifter.
As you can see, the big difference, especially percentage
wise, is going from any fixed to any adjustable lifter. If you think that weight is critical at the
RPM you expect to run, you should adjust your lifters by grinding, just like
Henry did.
If you are not ready to adjust by grinding, then use
adjustable lifters. Use lifters that
have slots or holes in the sides. The
lifters in the Flathead V-8 are all “solid” by type. This means that they are not hydraulic. Some are hollow, however, to reduce weight. The slots or holes in the sides allow you to
hold them without using the lifter wrenches at the top. It is difficult enough to get the thin 7/16”
tappet wrench between the spring retainer and the lifter boss, without trying
to also fit in a lifter wrench.
To avoid using a lifter wrench, drill a hole in the lifter
boss 5/32” diameter, as low as practical. Debur the lifter bore where the drilled hole enters. Then, after cleaning when you are setting the
valve lash, put a 5/32” allen wrench into the lifter slot or hole through the
drilled hole in the lifter boss. Why an
allen wrench? It is made of tough steel
and the adjusting torque will not shear it. Don’t use a nail. The
allen wrench also has a handle to pull it back out easily.
The mechanism that keeps the adjusting screw from turning in
the lifter body is clever. On most
Johnson style lifters there are two sections of thread, separated by a necked
down area. The pitch indexing of the two
sections is not the same. This stretches
the necked down area. The resulting
tension on the screw threads quite effectively keeps the adjusting screw from
turning in the lifter body.
There is another style that is used in some adjustable
lifters. It is much less common than the
one described above, in my experience. The bottom end is slit up the sides. The bottom end is spread open a bit, possibly after the adjusting screw
is assembled in the lifter body. They
also have a necked down area. The
springiness of the steel screw segments against the lifter body threads
provides the self locking action. These
do not seem to last as long as the first type. I have never been able to successfully get one of these screws back in once
it was completely removed.
I have never seen a flathead Ford adjustable lifter with a
free adjusting screw and lock nut. I
have seen an adjustable flathead Ford lifter that has a free adjusting screw
where the locking mechanism is a plastic locking compound, like
“Locktite”. The breakaway torque is over
45 ft-lbs. After it is turned out and
back in, the breakaway is under 12 in-lbs, or under one ft-lb. This is not satisfactory unless you can clean
the threads and reapply the locking fluid after each adjustment.
There is a current production adjustable lifter where the hex
turns the entire top of the lifter. The
adjusting threads have a plastic material injected into the center cavity and
out into the threads in four places. These appear to be working well in service.
Hardness should be Rockwell C scale mid-50’s on the bottom
of the lifter. You can check this with a
file on the bottom corner. If the lifter
is hard enough, it should not file readily – the file should “skate” on the
material without cutting.
|
