[TR] TR3 frost plugs

[Randall]

> Am I just blind or are there no frost plugs on my 1958 TR3 wet liner 4
> cylinder engine block?

You're not blind.

"Frost" plugs are actually core plugs, they plug the openings left by the
supports for the sand cores that form the cooling jacket when the block is
cast.  But since the TR3 block has separate cylinder walls (wet liners), the
sand cores can be adequately supported through the openings at the top and
bottom of the block, eliminating the need for holes on the sides.

There are still a few plugged holes, like the oil gallery at the front and
the cam bore at the rear.  There's also a core plug in the cylinder head.
But none on the sides of the cylinder block.

Randall