Pining the cyl head.

[Iestyn Guest]

Hi All -

I have seen the cylinder head pining that Alain talks about.  I watched it
being done by my automotive machine shop teacher in trade school.  (He did
the demo on a cast iron small block chevy head) There was a kit that he
purchased though.  This procedure is not one of those "just use any bolt
that fits" kind of thing.

The kit included the proper size dill bits, a special tap that looks like a
reamer, and a set of shear bolts.  Even the bolts are somewhat unique -
Designed to be installed with a butterfly impact gun, the head will shear
off right at the shank of the bolt, leaving almost no protusion into the
cylinder head.  After a series of these bolts have been installed, the
instructions (If I remember correctly) stated that the combustion chamber
where the bolts were installed should be piened heavily.

I'm not sure if the procedure was successful - We never reused the head.

Getting back to the dual spark plug thing, Bultaco, Motessa, Ossa just to
name a few, all used two spark plugs in there two-stroke motorcycle engines
back in the late 70's to the mid 80's. (Europe)

Nissan/Datsun also used a dual spark plug head in at least one of their
4-cyl engines.

Aftermarket  Porche cylinder heads can also be purchased with two plug holes
per chamber.

Having the second plug must do something!!

Iestyn Guest.