On Sat, 03 May 1997 15:25:44 +0000 Truxtun Southworth
<tsouthworth@worldnet.att.net> writes:
> ..... First, what gains should I expect from polishing the valve ports?
Not my area of expertise -- been trying to stay stock for so long that
this subject is a giant mental block. However, you might ask
larry.g.unger@lmco.com -- he seems to have quite an interest in this
area.
>I'm rebuilding the rocker shaft and also need to know the best method
for removing the rocker arm bushings.
Now this I have down pat, having done it twice, most recently just a few
weeks ago. Socket wrench sockets work well for this. Select one that
just fits over the outside of a new bushing. Select another with an OD
that's a smidge smaller than the outside of the bushing. The larger
socket fits against the side of the rocker arm surrounding the bushing.
The smaller socket fits on the opposite side against the end of the
bushing. Put the whole assembly in a vise and squeeze to remove the
bushing. Five minutes fiddling with the first one, one minute each for
the rest.
Before installing the new bushing you have to remove the drive rivet that
plugs a drilling hole at the screw adjuster end of the rocker arm.
Remove the adjusting screw first, of course. Grind the head off of the
drive rivet completely flush with the base metal. Clamp the part
securely in a vise, and use a punch and hammer to drive the shank of the
rivet through to the inside of the threaded hole. This takes a bit of
finesse, you have to get the angle of the punch to match the angle of the
drilled hole, and the punch has to be just the right size. If this fails
you may be able to drill out the rivet shank. Do not expect to be able
to drill the rocker arm itself, as it is a hardened part and will happily
gobble up drill bits with hardly a scratch to the part itself.
To install the new bushing, put the rocker arm bushing in a vise, place a
piece of flat metal stock between the bushing and the vise jaw to protect
the bronze bushing, and squeeze to install the bushing. After the
bushing is installed it will have to be reamed to size with 5/8" reamer.
If it is still a little snug an the new rocker shaft, you may have to
ream it with a bit more vigor or hone it slightly to get a good working
fit.
Also after installation you have to drill two holes for oil flow. One
hole is drilled through from the adjuster end of the arm where you
removed the drive rivet. This hole supplies oil to the top end of the
push rod via cross drillings in the ball screw. The other hole is
drilled at an angle through from the top of one shoulder on the arm.
This hole allows oil to squirt out in the general direction of the valve
contact end of the rocker arm. These drills are two different sizes.
Select the drills that just fit into the existing holes in the rocker
arm.
After drilling, you need to plug the hole at the screw adjuster end of
the rocker arm where you previously removed the drive rivet. If you
don't have new drive rivets of the correct size, I believe a #4 pan head
machine screw works nicely. Cut the screw to about 1/8" length and drive
it in with a hammer. If you're a bit superstitious you might apply a
drop of thread sealant before installing the plug.
And if you're going to all this trouble to renew the bushings, you should
also replace the rocker shaft. Seems like the shaft wears more than the
bushings, and it doesn't cost all that much for a new one.
Barney Gaylord
1958 MGA
|