MG Car Club of South Australia
MGC NEWS
MGC conversations with Richard Mixture, September 2019
Having a light head
ello, it’s Richard here again. Now
if you’re sitting back in your old
wing-back having a cup of English
Breakfast and pondering how you can
slim down your wallet and give your be-
loved ‘C’ a treat, give a thought to an
alloy head.
H
In the MGC’s nascent home father and
son duo Shaun and Conner Holmes
started racing MGCs after dipping their
feet into track-days which after a while,
they thought became a little mundane.
Speed being of the essence, develop-
ment work began and they thought a
nice light alloy head would be a good
idea. The search for a lightweight head
began in 2010 and after finding one
Shaun asked Peter Burgess to prepare it
to race spec using a new Maniflow mani-
fold which has straighter inlets. This
head was a success after the first race in
2013.
Never satisfied Shaun then decided to
cast his own alloy head and while the
first attempt worked well there were ob-
vious improvements that could be made.
Shaun says, “The MGC alloy head up-
dated casting has now been heat treated
and is on its way to the machine shop to
be finished on a new CNC unit which
should be the final form for all following
heads.
The main problem was wall thickness
around the plug. The walls are thin even
on the cast Iron head so for the first test
head I used a 10mm plug. We have in-
creased the wall thickness to the maxi-
mum without spoiling cooling round the
plug. We intend to continue to use the
10mm plugs which come in all heat
ranges. I am sure that someone in the
12
future will over torque a plug and the
head will need to be repaired and the
extra meat around the plug will allow for
this. The pattern has been adjusted to
allow some more material in certain
areas that we thought was needed.
A new set of valves has been made for
us to use which will be a nice improve-
ment in flow. The head has been fitted
with no issues, great work from the ma-
chine shop to scan the head and ma-
chine it to such tolerances that every
bolt fitted first time. The alloy head is
running well with no issues and over
2,000 miles now.
Of the six first production alloy heads,
two are off to Hawaii and California.
One is going on a race ‘C’ for vintage
racing. It will be interesting to see dif-
ference between the alloy head and the
cast iron head and we expect an in-
crease of 20 bhp.
We now have a reliable manufacturing
line, although only 6 heads at a time will
be cast. By years end we hope to have
14 Alloy heads done.
The amount of effort involved in bring-
ing an alloy head to the C community
has been huge on all parties from Steve
and I, to our caster, machinist and fin-
isher. In taking our time to get it right we
will ensure that the ‘C’ will have a re-
placement cylinder head for many years
to come.”
Shaun says, “I have always tried to sell
what I make for my own cars as a way
of offsetting development but now the
time has come to make a real business
of it.
MGC spares is run by Steve Curtis who
is a partner in our business and can