John:
Decking the block does something that shaving the head does not;
it brings the pistons closer to the head. On the TR6, the pistons are
recessed by about 0.016" when they are at TDC (according to Kastner).
Decking brings the pistons closer to the head, increasing
"squish". This occurs when the piston approaches TDC, and the air/fuel
is squished out from between the piston and the head into the open
combustion chamber. This increases turbulence and insures complete
combustion and increases knock resistance. The TR6 head is pretty good,
but it has only a small squish area. Modern heads have as large a squish
area as possible, given that the valves and spark plugs all demand room
in the head.
This was a secret racers trick for a few extra horsepower.
Decking the block by 0.015" will get you more power than shaving the
head by 0.015". Not only do you get a bigger bump in compression, you
get enhanced squish.
Decking the block by 0.015" will remove most or all of your
serial number. Ask you machinist to leave the serial number alone or
restamp it when he is done.
"Soda strip" is using sodium bicarbonate instead of sand in a
sand blaster. It is much gentler, and will not warp sheet metal the way
sand can.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of John & Allison Cyganowski
Sent: Monday, November 22, 2004 3:18 AM
To: 6pack@autox.team.net
Subject: Questions
Say, I have 2 questions about a couple of recent posts:
1.) What is "soda strip"? I am assuming this is a chemical strip of the
paint. Why would you want to do this instead of say a wire brush
approach?
2.) Why does one want to lower the block deck height? I assume that this
is
part of increasing compression? Is shaving the head not enough? I have
heard that decking the head removes the block s/n. Can it be
re-stamped?
John Cyg.
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