I decided to replace my leaking head gasket the other day. Since I knew the spark plug hole was pretty weak; I decided to replace the head too. What follows is a pictorial account (with comments) of my adventure which ends in a question.
I knew my head gasket was leaking because I could hear the engine wheeze, especially at startup. It also consumed a good deal of oil. The first picture shows what I found when I first "popped the top" on the K321 in my 149 S/N 2050047U464260 manufactured in March of 1973. I have probably 50 hours on this engine since I acquired the tractor. I've run 3 oz. of Marvel Mystery Oil to 10 gallons of premium in it all this time; I have no idea what was run in it before.
Notice the evidence of oil leaking out the front of the engine (toward the muffler) as well the discoloration at the rear (toward the tank).
I set the old head aside and cleaned up the top of the cylinder and valves resorting to sand paper to really burnish it up. The sand paper was really tough stuff, I don't think a lot of grit left it to get into the engine. There seemed to be two layers of accummulated carbon on the top of the piston. If I were doing a rebuilt, I would try to polish the surface of the piston top as smoothly as I could, as I've read that it cuts down on carbon accumulation.
Here is the new head ready to install.
The installation of the new head gasket soon came to a screeching halt when I discovered that the old bolts were too short to attach the new head to the block. The reason is because I had unkowingly purchased a "High Boss" head to replace the head installed in my 149.
(My son is holding both heads.)
I proceeded to run a tap through each bolt hole.
Next, I measured how far into the block the old bolts went.
And compared the depth of the new, flanged head, Grade 8 bolts I procured for TSC.
Note: The picture attempts to show that the depth of the hole as observed with the tap-in-the-hole is sufficient to accept the new bolt's 2-1/2" length. It looks like we're good to go.
Whoops! Old cover won't fit new head.
The picture doesn't show it well, but the old cover perfectly aligns with the head bolts.
So, does anyone know what cover I need for the head?
Does anyone know which models came with "high boss" heads from the the factory?
It's too late now, but I should have held both heads back-2-back to check the location of the spark plug hole. The spark plug hole in the new head appears to be slightly off center.