G'day
Yes that's true. Austin had massively overestimated the success of the A90
in the US. In fact when you look at the export figures far more Austin A90
Atlantics came to Australia than any other country.
No doubt the first Healey 100 had an A90 engine, but the engine in the
production 100 was slightly different. Put an A90 engine next to a 100
engine and it's easy to see that at the bottom of the A90 head there is more
metal (vertical part of the casting) due to the larger combustion chambers.
Then look at the thermostat housing and you will see that it is smaller in
the A90 and the A70 (2.2 litre version of the engine). The Weslake patent
mark is on them both.
One of the differences with the block is that in the A90 there is just a
single bolt to hold the distributor in place while there are two in the 100.
However I suspect that when BMC issued a replacement block they sent out an
A90 which would explains the number of 100s running around with A90 engines
in them.
Many years ago I used an A70 engine in the 100 I had at the time. A lot less
power and it would start to valve bounce in top overdrive at around 80mph.
Hoo Roo
Patrick Quinn
Blue Mountains, Australia
-----Original Message-----
From: healeys-bounces@autox.team.net [mailto:healeys-bounces@autox.team.net]
On Behalf Of Simon Griffin
Sent: Monday, 8 July 2013 12:00 PM
To: healeys@autox.team.net
Subject: Re: [Healeys] BN1 Head
Thanks Patrick. From reading the book and other written sources I had the
distinct impression that the engine for the BN1 was exactly the same as the
A90, and that was one of the motivations for Leonard Lord to get rid of the
over supply of these engines? What had prompted the posting in the first
place was the Westlake patent casting on the head of my car. I had Googled
some A90 engine shots and it looks exactly the same as my car.
> From: p_cquinn@tpg.com.au
> To: simon_grif@msn.com; healeys@autox.team.net
> Subject: RE: [Healeys] BN1 Head
> Date: Mon, 8 Jul 2013 10:29:54 +1000
>
> G'day
>
> The cylinder head for the Austin A90 is different to that of the 100.
> So is the cylinder block.
>
> The 100 combustion chambers are far smaller and along with altered
> ports provide an improved gas flow, plus the thermostat housing is
> much bigger in the 100.
>
> Whether the A90 design was returned to Harry Weslake Engineering or
> not prior to casting is not known, but I would be surprised if it wasn't.
>
> Hoo Roo
>
> Patrick Quinn
> Blue Mountains, Australia
>
> -----Original Message-----
> From: healeys-bounces@autox.team.net
[mailto:healeys-bounces@autox.team.net]
> On Behalf Of Simon Griffin
> Sent: Monday, 8 July 2013 10:12 AM
> To: healeys@autox.team.net
> Subject: [Healeys] BN1 Head
>
> I have been reading Bill Piggott's book about the 100 and of course
> there are several references to Westlake being contracted to design
> the head for the 100M. However, is it not fair to say that Westlake
> designed the stock cast iron head on the BN1? Or I suppose if being
> honest he desinged it for the A90, not the AH. Poking around and
> photographing everything today, I note a Westlake patent number cast
> into the head just in front of the #1 spark plug.
>
> Simon
> Troy, Il
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