Hi Gary,
I had the spark plug seats on my head machined in 1998.
No one I've spoken to since has said "oh yeah, knew about that" - most
Healey people had no idea until I discussed it here and put up that
webpage.
As for the excessive advance on a standard BJ8 - it's still a mystery.
As I've said before, I originally wrongly thought the 960 was specific
to the Bj8 - so that in some way explained the advance in my mind.
But the 960 head is not bj8 specific - so I still don't know why there
is so much advance in BJ8's.
Especially when a BJ8 has the 'hottest' cam of all stock C series
engines.
Best
Chris
Sent from my iPhone
On 21/09/2011, at 11:06 PM, warthodson at aol.com wrote:
> Chris & Mark,
> Thanks for the information. I checked my two 960 heads & they both
> have the plugs recessed in the combustion chamber as per Chris'
> information & photographs.
> If this is a machining mistake it is still a mystery why they never
> corrected it. And why the BJ8 is the only model a greater advance.
> Gary
>
>
>
> -----Original Message-----
> From: ardmorebusiness <ardmorebusiness at xtra.co.nz>
> To: 'Chris Dimmock' <austin.healey at gmail.com>; warthodson <warthodson at
> aol.com
> >
> Cc: healeys <healeys at autox.team.net>
> Sent: Tue, Sep 20, 2011 9:03 pm
> Subject: RE: [Healeys] cylinder head questions
>
> 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
> > _______________________________________________
> > Healeys at autox.team.net
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