so i have been perusing the archives looking for hints as i begin my
oil pressure gauge installation...  i see a lot of talk about
threading 1/8" npt into 10x1 mm and so on, but i haven't located much
info about the one aspect of this job that is scaring me--removing the
so called "engine tin," the protective plate installed below the
pushrod tubes which blocks access to the location of the stock oil
pressure switch that i am going to remove.

the reason that this scares me is that i once attempted to remove this
plate, sorry, i mean tin, when i was replacing my water pump and
wanted to flush the cooling system.  i had hoped to drain the coolant
from the engine via the drain plug located under the tin, but after
using more strength than i thought prudent, i was only able to get the
bolts out halfway!  of course i am referring to the bolts which attach
the down pipes to the exhaust manifold and also hold the mounting arms
for this plate.  apparently their lifetime of severe temperature
cycling has seized them up.  so here is the question i pose:  based on
the experience of the list, will i break the heads off these bolts
trying to remove them??  i do not want to be stuck with a leaky
exhaust and some sheared off studs that i will never be able to
remove.

how many people have broken these bolts trying to remove them?  if i
do get them out, will i need to run a tap into the hole to re thread
it?  does anyone know the sizes of these bolts so that i can have
replacements on hand?  any tricks for getting them out?

thanks!

Ben.