MG Car Repair: Valve Gap, train noise, weber carb

Question
QUESTION: Howard, I have a 1976 B, weber carb, iron head. The car runs great no issues. This is more of a curiosity question regarding valve adjustment. The manual states to adjust hot at 0.013, but many folks suggest adjusting at 0.015 cold, because by the time you complete the adjustment the car is no longer "hot."
Thank you,
mike

ANSWER: Hi Mike,
NO, NO, No, don't set it at .015" hot or cold. At the dealership that drove us to set all MGBs to .012" cold. The older MGBs were supposed to be set at .015" but that made noise and beat the valve train so that you had to reset often and resulted in many complaints. We switched to .012" cold and found quieter valve train noise and longer times that the valve clearance stayed constant. BMC and BLM missed the transition ramps of the cam and thus the noise and (which was banging of the clearances)

To confirm that we were not closing up the clearance too much, we tested several cars cold and hot and found that the difference in clearances was not more than .001" so we told BMC and later BLM that we were setting all our MGBs at .012". BLM finally listened and changed to .013"

Howard

---------- FOLLOW-UP ----------

QUESTION: I have them set at 0.013 hot.  Should I change to 0.012 cold?
Mike

Answer
13 is ok as it is hard to tell the difference because each mechanic has a different feel of the gauge, so one mechanic says he set it at 12 and the next mechanic checks it and says no you set it at 13. For your own info set it cold at 12 and run the engine to get it up to temp and check it hot and you will see not more than .001" difference. It is just that when you get the clearance up to around 15, it gets noisy and is beating itself to death. I think BLM just compromised when all of the dealerships started to complain. We were convinced that BLM didn't know what they were doing.
Howard