So again thank you all very much. Great information and I'm sure my friend
will be confused as I am. My thinking from everything I read is that an alloy
head is the way to go. Change out the pistons maybe, but it seems you get a
greater bit of reliability in this configuration and it will be well worth the
expense.
Again, thanks to the list! If and when my friend changes things over, I will
report the results and what he did.
Steveno;?
On Dec 05, 2014, at 02:00 PM, Andy Thorp <bce257@yahoo.co.nz> wrote:
> Hi Steven,
>
> I'm doing a little exercise on the early BN4 gallery head to see just how
"bad" it was compared to the later DMH designed one, and some of the things I
have discovered are very applicable to the four cylinder engine too.
>
> Despite the horrible intake gallery design of the early six cylinder head,
it actually flows no different to the later 3000 one when put on a flow bench.
The reason for this is because the majority of restriction to flow is the
inlet valve and combustion chamber area, rather than the actual intake tract.
The later head has bigger valves which for the intake gives better flow at
higher lift, and when a later intake valve is installed in the gallery head
plus grinding out metal around the valve, similar results are obtained to the
3000. The exhaust is marginally worse on the 3000 head than the early one
because the exhaust valves are bigger and get in the way of the flow out of
the combustion chamber. Attached are a couple of graphs comparing intake and
exhaust flow of the gallery head and stock 3000 head.
>
> So, to reiterate the well worn advice of anyone who has used a flow bench-
power comes from air flow and air flow comes from good shape around the valves
and into the chamber. Carbs and intake ports only make a difference if they
are the biggest restriction, and in the case of the Healey engine they are
not. You will make good power from a stock head with some time spent on
improving the air flow around the valves, plus raising the compression ratio
to a sensible level.
>
> Andy.
>
> --------------------------------------------
> On Sat, 6/12/14, Steven Kingsbury <airtightproductions@icloud.com> wrote:
>
> Subject: [Healeys] Increased Horsepower
> To: healeys@autox.team.net
> Received: Saturday, 6 December, 2014, 6:38 AM
>
> A short while ago, some listers were
> talking about getting increased
> horsepower in their AH 100's by just changing over to an
> alloy head with
> better breathing. Keeping stock carbs and still getting a
> great increase. Does
> anyone have any documentation as to the actual increase? The
> reason I ask is
> that I have a friend with another 100 and he's thinking of
> going with full M
> mods, (Cold air box, bigger 1-3/4" carbs, new manifold, new
> cam, valve
> springs, etc.) and keeping his iron head. I told him about
> the talk here about
> the alloy head and before he jumps in to the rebuild, I'd
> like to pass along
> some information before he gets too far in to his project.
> Thank you all in
> advance for your information.
> Steven Kingsbury
> BN1 #598o;?
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