12g940 head rebuild

Tearing into the head tonight...

Pre A+ head (flat area behind thermostat housing)
12G940 casting number
501 designation just below casting number

Valve length:
3.57

Intake dia:
1.33

Exhaust dia:
1.15

*side note: top caps were fitted to intake valves... this is odd, if you only have 4 then they should be fitted to the exhaust side.

Single groove collets

Spring free lengths:
1: 1.92
2: 1.92
3: 1.93
4: 1.92
5: 1.93
6: 1.92
7: 1.92
8: 1.92

Some of the valve guides are badly worn.  Only in the exhaust valves, all intake valve guides still feel good.


cylinder 2

 cylinder3

Uneven fueling from the twin carbs possibly?