Aluminum heads warp due to a difference in TCE (thermal coefficient of
expansion) between the aluminum head and the CI block. Aluminum expands at
about twice the rate as CI. Under normal operating temperatures the head
will expand about .0007 inches more than the block. The design takes this
into account. If the engine overheats, this difference increases, and since
the head bolts don't allow the head to move, the aluminum will warp (it's
got to go somewhere!). Since a CI head matches the TCE of the CI block,
this combination will not warp. Since I have removed, flattened and
replaced the head on my '70 1600 several times after the engine overheated,
my preference for day to day driving would be for the CI head! Either that
or NEVER let your roadster overheat!
Tom Notebaart
'70 1600
'69 2000
-----Original Message-----
From: Adam Bradley [mailto:ambradley@yahoo.com]
Sent: Friday, August 03, 2001 2:52 PM
To: Christopher Coker; Datsun Roadster Mailing List
Subject: Re: iron head
Well I've never had a CI head and am not a race car driver or an
engineer, but nearly every R16 I've owned has experienced head warpage,
and they all had aluminum heads.
My first RL411 warped after I owned it for six months, although there
had been symptoms for about a month before that. My first Roadster
warped when I put the engine back in after replacing the clutch, then
again when I moved the engine from one car to another. I'm assuming it
was due to too much air in the cooling system that I didn't "burp"
properly each time.
My last one had very minor warpage around some water passages that may
or may not have contributed to the head gasket/overheating problem.
My question isn't which is better, but has anyone with CI heads had
head warpage? I thought it was nearly impossible...
--- Christopher Coker <cfcoker@home.com> wrote:
> I have to agree here. Aluminum's heat dissipation qualities are
> preferred
> over those of cast iron. You save a significant amount of weight
> too. Make
> sure the cooling system is up to the task of the increased hp, and
> warping
> shouldn't be a problem.
>
> I have a cast iron head on my race car right now, but only because
> that's
> the way the car came. I have three bare aluminum cylinder heads as
> spares.
> When I build up the three-main motor over the winter, it will have an
> aluminum head on it. Right now I'm hoping to get 140-160 horsepower,
> and
> will go up from there.
> > From: "Henry Bahn" <hbahn@home.com>
> > Reply-To: "Henry Bahn" <hbahn@home.com>
> > Date: Fri, 3 Aug 2001 15:17:13 -0400
> > To: <datsun-roadsters@autox.team.net>
> > Subject: iron head
> >
> > We had this discussion about a year ago, and Joe Hauser pretty much
> put it
> > to rest. The alum.head has better heat dissipation, not worse,
> than the
> > cast iron head, and is not more likely to warp. Claims of
> increased HP from
> > the iron head just ain't so. I don't think anyone is using CI
> heads for
> > competition roadsters.
>
> Happy roadstering,
> --
> Chris Coker
> 69 1600 SPL311-24529
> <http://members.home.net/cfcoker/roadster.html>
> 6? 1600 GP Race Car
> <http://members.home.net/cfcoker/racecar.html>
> Royal Oak, MI
=====
Adam
'70 1600 SPL311-28181
http://www.picturetrail.com/abend
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