Chris and Gary,
I also have an original works head. It too has the AEC 721 number
cast into the top.
As an aside, I was told long ago that the heads were made 'after
hours' when production had stopped for the day. They were apparently
made from recycled diff. heads that had been melted down.
I've not done a side-by-side comparison of the 721 and the 960 or
blue-printed either of them, but I have been told that there is also a
slight difference in the squish area in the heads, the 721 being
considered the better designed one.
One of our racers here in NZ actually replaced the 960 on his BJ8 with
the 721. He reckoned it gave him a marginal improvement in
performance. I don't know how scientific his analysis was . . . that
was back in the 70s.
Cheers
Mark Donaldson
Auckland. NZ
-----Original Message-----
From: Chris Dimmock [mailto:austin.healey at gmail.com]
Sent: Sunday, 18 September 2011 12:50 p.m.
To: warthodson at aol.com
Cc: healeys at autox.team.net
Subject: Re: [Healeys] cylinder head questions
Hey Gary,
Factory alloy heads are all based on the AEC721 - the original 12 port
head - casting. Even Joe Armors BJ8 based 1965 Sebring car has a
factory alloy head based on the earlier AEC721 casting, not the later
3000 AEC960 casting.
Denis Welch wanted his head accepted by the FIA - it had to be a
replica of the factory alloy head. Hence AEC721
All the AEC 960 heads i have seen are wrongly machined. See
http://www.myaustinhealey.com/aec960-healey-cylinder-head.html
Chris
Sent from my iPhone
On 18/09/2011, at 1:15 AM, warthodson at aol.com wrote:
> A friend purchased a Healey 6 cylinder head at a swap meet recently.
> It has
> AEC721 cast into it. My BJ8 head has AEC960 cast into it.
> Interestingly, the
> Denis Welch aluminum cylinder head has AEC721 cast into it. How many
> different
> 6 cylinder heads were fitted to the big Healeys & what were the
> differences
> between them? Is there any reason you know for Denis Welch using
> the AEC721
> for the basis of their aluminum head? I did notice that the boss for
> the water
> temperature sensor is much more accessible (I.E. getting a wrench on
> the nut)
> on the AEC721 vs. the AEC960 which raises the question why did the
> factory
> change the design?
> Gary Hodson
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