My recollection is that the standard for the U20 head is 0.0019 inches.
Jim's experience is why Nissan ran out of U20 heads very early. We're very
fortunate that they spent the money to have new tooling made to reproduce them
, what, 25 years ago? And then sold them for a reasonable price. (Not at
first, but they dropped it rather quickly, as I recall.)
Gary Ault
----- Original Message ----
From: Jim Gammon <gtpjimgammon@yahoo.com>
To: "Datsun-Roadsters@Autox. Team.Net" <datsun-roadsters@autox.team.net>
Sent: Thursday, March 6, 2008 6:50:09 AM
Subject: Re: [Roadsters] Cylinder head
Years ago I had a head warp on my first roadster, and like an idiot, I had it
shaved.
A few weeks later the cam broke in half.
You can't make this stuff up.
Jim
Dave Stoll <dgstoll@verizon.net> wrote:
There is a tolerance for how flat the head is. None are perfectly flat. If
the head is curved so that the ends touch the top of the block first, by
starting torquing the bolts in the middle first you pull the curve down and
flatten the head. If you were to start tightening the bolts at the end first
it would be much harder to pull the head down flat in the middle..we are
only talking a couple thousandths but thats all it takes to get a leaky head
gasket.. I believe the tolerance on the 1600 heads is .003 to .005
thousandths of an inch or about the thickness of a piece of notebook
paper...
daveS
----- Original Message -----
From: "dave"
To: "'Bubba'" ; "'Datsun-Roadsters@Autox. Team.Net'"
Sent: Wednesday, March 05, 2008 8:36 PM
Subject: Re: [Roadsters] Cylinder head
>I never heard that before, I didn't think a cold head woul warp from the
> torque being let off unevenly, but I guess it's possible. Not refuting
> it,
> just news to me.
>
> Dave Brisco
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