Early BL workshop manuals for the V8 engine used to advise that leads 5 and 7 should not run next to each other because it can induce misfires. This may not apply with modern HT leads.
Nov 98
I have a 4 year old 4.0 Chim. And have also recently cut down on the milage that I have been doing. I have had it for a year and had little
to no trouble.
Apr 97
My car is a standard Chimaera 4.0 which was built in June 1996
and which I have owned from new. I seem to have had my fair share
of minor niggles which have mostly been quickly rectified by Broughtons
at Cheltenham. The one disturbing problem was during the 1000
mile service. When changing the plugs, 3 out of 4 NGK plugs on
one side sheared off just below the hexagon, leaving the threaded
and cylindrical part of the plug stuck in the head. TVR's solution
was to send a replacement head and they claimed to have received
a faulty batch of NGK plugs. Incidentally, Broughtons have had
the same happen on a Rolls Royce which they put down to the use
of counterfeit NGK plugs at a previous service (not by them I
hasten to add).
Steve Cooper
However, we are increasingly desperate to get hold of tuning specs
for the car, namely the tuning at idle, and other rpms other than
the 28deg @ 3750rpm. I would appreciate if you could help me obtain
this information or direct me to a person who could and their
contact numbers. I hope you can understand as we are quite far
away here in Singapore. Even though TVR Malaysia is nearby, they
are not familiar with the 5.0HC engine.
Kenny Heng
Oct 96
I have had a telephone conversation with TVR Power about ignition
timing and the answer may surprise you. The distributor used on
all TVR engines is a completely standard Range Rover unit. Because
it is a standard part, TVR have never felt it necessary to hold
information on the exact characteristics of the advance curve,
so they can't tell me anything. Any Range Rover dealer should
be able to find out for you, if you give them the number on the
distributor body. Apparently the different advance figures given
on the engine spec sheets I was sent are purely down to different
static advance settings. All current cars (400s and 500s) are
being delivered with this set to give 28 degrees at 3750 rpm so
the figures in my table [above] are out of date. I think you will
get 28 degrees at 3750 by setting the static advance to about
2 or 3 degrees, but a Range Rover dealer should be able to confirm
this.
I have, by the way, also spoken to JE Engineering in Coventry.
As well as producing performance conversions and big V8s for Range
Rovers, JE also do engine development work for the Range Rover
factory. They have a policy of not fitting aftermarket chips or
modified distributors because of the problems customers have had
getting their cars serviced at main dealers once this has been
done. They guessed that this was why TVR had stuck with a standard
distributor.
Peter Beech
Oct 96
We found the tuning specs from a Land Rover manual and for all
their V8 engines, the static timing is 8 deg @ 700rpm. We took
the car to a garage here, who specializes in British cars, to
have it adjusted. Here's what we found;
1. It was difficult to make any absolute readings because of the pulleys and the position of the marker and its access with the strobe and viewing angle. However, we could make out that it was retarded rather than advanced! We could see the marker on the "AFTER" side of TDC.
2. We proceeded to advance it by rotating the distributor clockwise a fraction at a time until we were sure it was advanced (on "other side" of TDC ie BEFORE). Since we couldn't see any markings for position of distributor, this was done with eye-ball guesstimation and feel.
3. Further fine tuning was done by advancing further in minute increments, then driving the car repeatedly, to the point the engine began to knock. At that point we retarded by rotating anti-clockwise. We have no access to a rolling road, which would otherwise be ideal for this. Un-scientific as this was, it seemed to do the trick for now. The engine idled even better, and was able to pull much better (in terms of absolute acceleration and smoothness) from lower rpms. How much this is due to tuning, and how much attributed to Superchips is unknown. Sometime later, we will re-fit the original TVR chip and make a better comparative assessment. The car nonetheless is running better now than it ever did.
I still find it difficult to comprehend that a Griff 500 engine is still very much stock Land Rover. I would like to get hold of a book which describes the Land Rover V8s well. Do you know of any?
One other interesting observation was that after advancing to
the point mentioned above, the engine seem to run about 2 degs
cooler at 89 degs. Does advancing ignition timing usually result
in lower engine temperatures?
Kenny Heng
Oct 96
Pleased to hear you've had some success. There are two books about
Rover V8s that I think are very good, both written by David Hardcastle
and published by Haynes (they cost about £15-20 each):
The Rover V8 Engine, 1990, ISBN 0-85429-629-1.
Tuning Rover V8 Engines, 1993, ISBN 0-85429-933-5.
Obviously they are a little out of date as far as the latest versions of the engine are concerned, but interesting reading all the same. Incidentally, neither of the above books have much to say about ignition timing, which rather suggests that engines in various stages of tune are pretty happy with the standard advance curve.
I believe very retarded ignition does cause overheating. If you
think about it, the fuel is igniting later than it should and
probably still burning when the piston has finished its combustion
stroke and is on its way back up the cylinder on the exhaust stroke,
thus some of the energy from each combustion is actually trying
to make the engine go backwards! Another nasty effect is that
the exhaust valves are partly open while the fuel is still burning,
which can eventually burn the valves out.
Peter Beech