I think the rest of you are missing the actual question. 1957BIRD is asking about a shield for a dual chamber
master cylinder heat shield, not a shield for an
oem single resevoir
master cylinder. That said i have not seen a shield to use when converting to a dual chamber
master cylinder. that does not mean one is not available, it means i have not seen one. It could be fabricated relatively easily. Yes metal can be a heat shield acting as a heat barrier/deflector. I have often contemplated making one for my own disc conversion
master cylinder. I know the clearance is close. I have not experienced any problem with boiling brake fluid as of yet. I have on more than one occasion driven long distances at ~70.mph cruising speed for hours on end without a problem as of yet. I think the idea of a deflector shield is a good idea.