okie-dokie!
lets go down this bumpy road...
evryone flip over there cylinder heads and read along....lol!
those brass plugs on the bottom side of the head. the more you shave a head
the greater chance they will fall out into the head! now, they do not go
for a wander about in the engine because they are too big to get into the
block. but! some are casting plugs (the solid ones) and some are coolant
restrictors to controll flow through the head(the ones with a center drilled
hole). quite frequently a severly shaved head gets to the point where these
brass plugs are so thin they will come out of their pressed in fitted holes
due to expansion and contraction of the head. they will not "fall out"
during the milling process or during installation. but blow a head gasket
and pull the head and you find "something missing" upon inspection of the
head when you read the gasket seeking for the cause of failure?
the cure is to remove all the plugs(brass ) and have threaded brass plugs
put in so the threads hold the plugs from coming loose in their bores.
going for an optimum compression ratio is fine going for an optimum
combustion chamber size is pretty cool too! but going into severly shaving
a head leads to some funky problems with those brass plugs wich for the most
case you will never see in a street motor!
also! beware of seriously shaving the head! you take a lot off and you will
need shorter push rods in order to retain proper geometry in relationship to
the rockers and valves. also you jeopardise the piston to valve clearnaces
at full lift (or full open of the valve).
the closer you get to "no more room for improvement" you go the closer to
"grenade " you get(ask the racers on this one!).
in adition. with the frequency of overheating and tendancy for warpage
these heads get....i'd shy away from shaving the "living daylights" out of a
head. you want to true the surface and raise the ratio and reduce the CC's
a bit but yet leave enough meat on the head for future resurfacing if needed
. plenty of really hot(performance) heads have been trashed due to running
out of metal to cut away to repair mating surface irregularities. in
adition, the thinner the head gets the more likely to distort if subjected
to extreme heat from overheating. a casting is generally designed for
function and ease of casting in manufacturing. but it also is designed to
be a stable casting in it's aplication too. the more you modify the
original design the more you compromise the casting's stability. this is
not a problem with mild modifications. but when you seriously get into
hacknig away metal.....you can bring upon problems that rank in the "why me"
catagory.
chuck.
doing a washington DC and back run today.....yawnnnnn 6:35am gotta get ready
to roll out!.....c.
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