The thermal air valve is a valve that look like a tee on the STARBOARD cylinder head.
It controls air flow through the idle circuit of the carbs, and when cold (closed) it enrichens the low speed mixture of the idle circuits.
When it opens (at around 100 degrees ), air is supplied to the...
The poppet/t-stat housing has to seat firmly against seal in head, leakage will cause the leaking side to run hot. It is normal to see the starboard side to run 10-15° hotter than port.
Needs torn down, that cylinder bored and possible the others depend on how they "mike" out size wise. After you fix the result, you need to address the problem as that is preignition, either coil/pack ot timer base problem
Cannot set timing on a 60° motor with timing light, the flash will cause the optical sensor to read incorrectly, must use analyzer. Joes method will not work on 60° engines
