On Wed, 5 Jul 2006, Navarrette, Vance wrote:
> Kas Kastner in his competition manual says most TR6s are about
> 0.017" recessed. You should not need to worry about this however. Just
> tell your machinist you want the block "Zero decked" and he will measure
> it and get it exactly right.
Hi, this is my initial post and I have some questions about "zero
decking". I pulled the head off of my 74 last week to chase down some
stubborn tapping noises, and found some problems. The most shocking thing
was my #6 piston: http://zeni.net/~derick/brokenpiston.jpg
but #1 is also cracked.
The deck appeared to be zero-decked by eyeball, but I didn't confirm
this before removing the pistons. The piston tops show compressed carbon
where the solid part of the head is above them.
Does it seem like the fact the the pistons were essentially hitting the
head with a "cushion" of carbon be a factor in the state of the pistons?
It was suggested to me, and I currently believe that the block must have
been race-prepared with the cylinder walls overbored for the .020 pistons
that were in the car when I got it. This would explain the fact that this
is the second and third broken piston since I acquired the car, and the
strange wear pattern on the rings. The only history on the car when I
bought it 15 years ago was that it had spent the previous 8 years in a
field.
The Bentley book says .020 over is maximum on these engines, but I've seen
pistons advertised as high as .040 over.
So, I guess that my non-deck related question is, is the .020 maximum bore
conservative, or is the .040 option crazy? Or both?
Thanks for any attention or advice,
-Don
|
