[Roadsters] Valves leaking while cc'ing

[MH]

I have a spare late, smog R16 head that does have brass intake seats and
steel exhaust seats. I'm scratching my head wondering what is the reason for
this if it left the factory that way. I'm confused by the this and other
info I've read, and maybe I'm just not reading it write. I'm hearing that
some say to replace intake brass with steel seats, and others saying to
replace brass exhaust with the steel ones. It seems like it should be steel
for exhaust seats because of the heat, but why would brass be a problem for
intake valves? Need some techno here!

Which is what? and why? ........again please.

Mike Hudson  '67 - stroker / 5-speed

----- Original Message ----- 
From: "Steve Ehlers" <stevenehlers at charter.net>
To: "Daryl Smith" <drlsmith at dccnet.com>; <datsun-roadsters at autox.team.net>
Sent: Monday, September 15, 2008 7:37 AM
Subject: Re: [Roadsters] Valves leaking while cc'ing


>    Hi,
>       If  you  have  Brass  intake  seats  ,which are sock , They MUST be
>    replaced .They will be pounded-out and a stock valve will be "sunk" in
>    the head and will fall out of the head eventually .
>       If  you  have steel ,or a derivative ,you  may be  ok . That said ,
>    Nissan  does  not publish actual valve heights/ Stem lengths  ,so they
>    could  not  duplicate the dimension . They may have had spring heights
>    dimension  ,that  is  controlled  by this number ,however their method
>    would  have  involved  using valve shims under the valve springs .This
>    doesn't  change the relationship with the actual stem length ,or valve
>    position  relative  to  the  seat  . Since you had them install bigger
>    valves  ??  ,  that  would have raised the valve and made stem lengths
>    shorter
>    than  spec  ,possibly . Anyways , Seat material used in the 1960's was
>    designed for Leaded Gas ,how would they know  ,unless the seats
>    had bean changed ?
>     Steve Ehlers
>    www.risingsunperformance.com