UPDATE:
As I was cleaning parts/bolts/threads/etc. in preparation for re-assembly, 3 things caught my attention that I didn’t notice on initial tear down, and it’s clear someone “tried to fix it” at some point.
1) The intake valve stem cap was missing, so the intake rocker had been tightened down to contact the stem directly. No damage to rocker or valve. B+S diagram shows both stems with caps so I replaced both with a new set.
2) A single head bolt was missing completely (pos.# 8 in the torque sequence) and for long enough that grass/grease/oil/etc. had completely covered the bore - threads in the block were pretty clean, but they were cleaned/chased w/ lube, tap & compressed air, along with the other 7. Replaced bolt.
3) Both of the alignment dowels were also missing. I found the shank of a 1/4” bolt fit perfectly into both block & head, so I cut 2 replacements off a 4” hex bolt and chamfered/smoothed the edges.
Cleaned everything, re-assembled using permatex copper gasket spray, torqued bolts in stage and sequence, set valves, installed manifolds, and so on.
It cranked steadily but was still struggling with the compression stroke - maybe the comp. relief lobe is worn??
BUT - it did fire, sputtered for a moment, then smoothed out and started running smooth just like before.
5 minutes into the test mow, the spark plug thread insert fails and isn’t pushed completely out of the head, but the aluminum threads around the insert basically just crumbled when I attempted to remove the plug.
So now I’m waiting for my boss to tell me if we’re gonna replace the head or if the customer wants to even pursue further repairs.
But hey, at least the new head gasket remained in tact.
As I was cleaning parts/bolts/threads/etc. in preparation for re-assembly, 3 things caught my attention that I didn’t notice on initial tear down, and it’s clear someone “tried to fix it” at some point.
1) The intake valve stem cap was missing, so the intake rocker had been tightened down to contact the stem directly. No damage to rocker or valve. B+S diagram shows both stems with caps so I replaced both with a new set.
2) A single head bolt was missing completely (pos.# 8 in the torque sequence) and for long enough that grass/grease/oil/etc. had completely covered the bore - threads in the block were pretty clean, but they were cleaned/chased w/ lube, tap & compressed air, along with the other 7. Replaced bolt.
3) Both of the alignment dowels were also missing. I found the shank of a 1/4” bolt fit perfectly into both block & head, so I cut 2 replacements off a 4” hex bolt and chamfered/smoothed the edges.
Cleaned everything, re-assembled using permatex copper gasket spray, torqued bolts in stage and sequence, set valves, installed manifolds, and so on.
It cranked steadily but was still struggling with the compression stroke - maybe the comp. relief lobe is worn??
BUT - it did fire, sputtered for a moment, then smoothed out and started running smooth just like before.
5 minutes into the test mow, the spark plug thread insert fails and isn’t pushed completely out of the head, but the aluminum threads around the insert basically just crumbled when I attempted to remove the plug.
So now I’m waiting for my boss to tell me if we’re gonna replace the head or if the customer wants to even pursue further repairs.
But hey, at least the new head gasket remained in tact.