The August issue of ACtion, the AC Owners Club (ACOC) newsletter, had a
couple of interesting items in it. A photograph of the stylish new AC
Ace prototype appeared on the cover. It's a "roadster" and looks like a
cross between a Miata and a Viper. Very nice lines. According to an
article by ACtion editor Colin Dunn, Ford will provide their MT75, 5
speed, four wheel drive transmission for the new Ace. Ford recently
relinquished its 50% share of A.C. Cars but cooperation between the two
companies will continue on the development of the Ace. The plan is for
a European version powered by a V6 Cosworth engine and a U.S. version
mated to the Yamaha Ford SHO/V6. No introduction date was mentioned.
It really is a nice looking car. I hope AC can pull it off.
There was also an interesting article written by a member entitled "The
Saga of a 100 D2 Bristol Engine". It describes the trial and
tribulations encountered during the rebuilding of a 6-cylinder 2 litre
Bristol AC Ace engine. Most of the problems centered around the rings
not lapping in properly. The initial plan was to have the cylinders
bored out and fitting oversized pistons. But the only suitable
replacements were much heavier than the original forged pistons so it
was decided to resleeve instead and go with the original pistons. This
was done and the new liners were honed to the proper dimensions and new
rings were fitted to the pistons.
After 500 "gentle" miles, oil consumption was very excessive so the
owner started checking with Bristol "experts" as to whether or not this
was normal. Some said yes, just keep pouring in oil and everything
would be hunky dory by 10 kmiles or so. Others suggested that the
modern oil he was using was too slippery for initial break-in and also
that he should have been driving a bit more vigorously. So the oil was
switched to a lower specification grade and "the throttle was opened
wider". After a couple of thousand miles, things hadn't changed much so
the oil was downgraded again. Things did improve slightly but no
dramatic progress was noted so it was decided to dismantle things and
have a look.
Sure enough, the bores had glazed. They were de-glazed and some
machining work was attempted on the rings. Unfortunately one ring broke
during the process and a new set had to be ordered. The new set turned
out to already be close to the desired thickness so no machine work was
done on them. After verifying that everything else was okay, the engine
was reassembled and SC spec 20/50 oil was added. This did make a an
improvement after a reasonable length of time but #3 and #4 plugs were
still fouling excessively. Faced with the prospect of yet another
dismantling, the author cast about for alternative remedies. One such
remedy was to feed various fine abrasive into the air-intakes of the
offending cylinders. One suggestion was finely ground glass but he
rejected that idea. "So, throwing caution to the wind, a very small
quantity of jewellers rouge was introduce to cylinders 3 and 4". I'm
sure I winced noticeably while reading this.
The author claims that a noticeable improvement has taken place in both
the compression and oil consumption of number 3 and 4 cylinders though
he admits that he's not convinced that the problem will ultimately be
cured when the break-in period has ended.
Roland
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