Distributor options for the
Gordon Hesketh-Jones (Harvest Gold 1907) from Cornwall uses his car
all the year round and with a total mileage now rapidly approaching
400,000 so has a great deal of experience of maintaining the model
from his regular servicing work and numerous rebuilds. One regular
service difficulty is with worn distributors, so he set about some
research into the options for the V8 which he reports on in this note.
efficient distributor is clearly at the very heart of an engine and
now that our cars are 30 or more years old, age will take its toll.
A further problem is that whilst I personally have two excellent distributors
both rebuilt by Holden (who purchased all of the rights, tools and
stocks of spares for the Lucas distributor range when Lucas dropped
out of that business), the quality of the contact sets and condensers
now sold - even if they have a famous name on the box - is abysmally
low. On my car over the past two years three different sets of contacts
have lasted less than 1,500 miles before either developing "pips"
or, in one case, the fixed contact stud "un-riveted" itself
leading to a very variable spark effect! It seems that, whether I
like the idea or not, I have to go for an electronic add-on to the
distributor in some form just to get away from the points and condensers.
So I set out to explore the market and look at the options.
Starting from basics, the distributor fitted to the MGBGTV8 is the
Lucas 35D8 to specification 41394 which is similar to that used on
the Range Rover, but with different (faster-acting) advance/retard
and bob-weights. A unit to an almost identical specification was also
used on the Rover 3500 and 3500S, but a very different specification
applies to the SD1. If your distributor has covered more than 100K
miles there will certainly be wear on the pinion, the shaft, or the
bearings. If any one of these is badly worn or if all three are slightly
worn, the result will be erratic firing of the plugs and this random
output from the distributor shows up very clearly on a Crypton or
similar engine analyser. Even on my current Holden distributor which
has done less than 34K miles since the rebuild, the outline of the
trace on the Crypton screen is fuzzy and slightly curved instead of
being sharp and straight, indicating that one of the three wear points
probably not replaced - the pinion, bearing or shaft. Note that
one of the most common problems with the 35D8 unit is that the advance/retard
capsule diaphragm degrades (hardens) over time due to the ingress
of petrol vapour so changing this is an easy and cheap action (costing
around £25) which you should undertake in any case before
looking at other options.
If you are fed up with the problems caused by poor-quality points
and the other difficulties, and the screen trace of your high-voltage
output is not perfect, the question therefore is whether to go for
one of the various contactless distributor arrangements, or to buy
a new distributor. It really depends on the mileage and amount of
wear on your existing unit. If the shaft and bearings are badly
worn, then it may mean that fitting a proprietary electronic kit
will not give you all of the benefits you had hoped for, so it is
worth looking at the output of your distributor on an engine analyser
screen before spending your money.
When fitting any form of electronic kit to your distributor (either
opto-electronic or Hall effect-magnetic) which does away with the
points, you need to be aware that this will change the character
of the advance curve of your distributor. This is because the curve
has been plotted with the points in place, so if you take them away
then the mechanical load on the shaft and cam is no longer there,
and the normal contact bounce no longer affects the movement of
the bob-weights. The change might be minor within the generous torque
curve of our V8 engines but will normally mean that there will be
less advance at lower revs, although in the end the total amount
of advance provided should be the same, but at higher revs.
Many suppliers of electronic-assisted distributor kits advocate
the fitting of high-voltage coils, but if you do this you will need
to change the wiring to your coil. Basically the standard coil is
a 6volt device fed during normal running via the ballast resistor;
the 12v supply to the coil only cuts in you're your starter motor
is engaged, in order to give an extra kick to the coil. There is
no doubt however that more than doubling the voltage to the plugs
by using one of these high-voltage coils, added to the longer dwell
(coil re-charging time) provided by the electronic kits will greatly
improve both starting and running.
on the various electronic ignition systems available for the MGBGTV8
On the face of it this London-based firm should be the obvious
first choice for an add-on system as they have 30+ years of experience
and half a dozen patents, however in the early 1980s I fitted one
and it - plus two replacements - and they all failed, so I am biased
against them. Their system comprises an infra-red generator (LED)
with a photocell receiver and an eight-lobe signal chopper, these
three items are located inside the distributor cap, then there is
an additional black box containing the electronics to be mounted in
the engine bay. The standard kit (which is not for high-performance
or racing applications) for an MGBGTV8 costs £168 plus postage
and VAT and can be bought from most MG accessory dealers. The high-performance
kit (for high-revving), which includes a new coil, costs £258
plus postage and VAT. There is a 12-month warranty on Lumenition products.
Incidentally the product name is derived from lumens. In the good
old days before the metric stuff came in, "lumens" were
the units for measuring the brightness of light so as the first ever
product of the company was the opto-electronic ignition. The company
name came from combining the unit of light measurement with "ignition".
It is worth noting Lumenition now also manufacture Hall-effect distributor
kits, but not for our 35D8 unit.
This successful company started making electronic ignition kits for
racing motor-cycles in 1969 and most of their business is still in
motorcycles plus F3 and classic racing cars, however they make a cheap
and simple kit for classic cars which retains the contacts. The unit
uses the points to switch the electronics which is in a small box
external to the distributor. As the points no longer switch any serious
voltage or current their life becomes infinite, and the exact points
gap is no longer important. The company is based at Maidstone in Kent,
(Tel 01622 730939) and their Contact Assistance Kit costs £29.93
including postage and VAT.
Based in Dudley (Tel 01384 572553) this firm manufactures a wide range
of engine tuning kits - much of it aimed at Fast Fords etc but they
also are a major supplier and tuner for Caterham Cars and have two
rolling road dynamometers for engine tuning. Their "Ignitor"
kit fits entirely inside the distributor cap with no external electronics
box and is said to give 26K to 27K volts to the plugs with a standard
coil, or 30K to 35K volts when used in conjunction with their oil-filled
coils. For reference the standard set-up on the MGBGTV8 gives 18Kv.
Their system relies on Hall-effect (magnetic) sensors rather than
the opto-electronic sensors used by Lumenition. Apparently two types
of base plate were fitted into the 35D8 distributor; for the round
base-plate the price is £65 plus postage and VAT, and for the
triangular base plate £70 plus postage and VAT. Their kits come
with a 30 month warranty.
The OPUS unit was fitted to the SD1 from 1976 to 1984 in various forms
as they tried to achieve reliability and the final version 35DLM8
with the chip mounted on a heat-sink on the side of the distributor
is currently being advertised by Rimmer Bros (Tel 01522 568000) at
£235 plus VAT. The Rimmer website makes it clear that these
did not come from the vast stocks of SD1 parts which they found in
India and recently repatriated, but unfortunately the nickname of
OPELESS applied by the trade to these units was well deserved and
it should be noted that for reliability reasons the Range Rovers stuck
to a version of the 35D8 with conventional points right through to
This is an American kit using the Hall effect principle that has been
in production for a wide range of vehicles for nearly twenty years.
Information on their website is a bit sparse but as I understand it
they provide a circular plate into which they have mounted eight magnets,
with the Hall effect device contained in an epoxy moulding which also
fits inside the distributor cap - so no external box is needed. Their
early products were for use on VW's then on Porsches so it is no surprise
to find that their UK distributor is Maxted-Page & Prill Ltd of
Halstead some 17 to 18 miles from Chelmsford, tel 01787 476338 who
are Porsche specialists - including racing success at the Le Mans
Classic event. Their model number for our car is LU181, price £79.95
+postage plus VAT. Their high-voltage coils work out to £66
plus postage plus VAT.
This firm, based near Malvern (Tel 01886 880101) specialises in the
manufacture, overhaul and repair of all types of distributor for UK,
European or American vehicles. They can machine up new parts for the
Lucas 35D8 etc but their recommendation for all old distributors is
to fit their Hall effect magnetic unit which fits entirely inside
the distributor cap - no external electronics box is needed but as
with all electronic units, there is a two-wire connection to the coil
instead of the standard single wire. The standard rotor arm is retained
as the "chopper". The unit for the 35D8 costs £93.90
plus £6.00 postage and VAT, and they are prepared fit their
kit and also to overhaul your unit if required. They give a two-year
warranty on their kits and I like the fact that they do much work
for the military, where the requirements for reliability are high.
This was another early pioneer in the transistor-assisted ignition
market but they went into liquidation in March 2006 and their assets
and designs were bought by Autocar Equipment Ltd
make the Lumenition range. The Piranha units are now marketed under
the name NEWTRONICS; their TO5A kit for our cars costs £66.49
plus postage and VAT and has a 12 month in-car warranty. I understand
that in future the Newtronics range will focus on motorcycles leaving
Lumenition to cover the car market.
Based in Holland this company has for many years produced new distributors
for a wide range of continental classic and vintage cars, then some
years ago started to make counter-clockwise kits for UK cars. Their
approach however is quite different from the firms listed above
in that they dispense with the points-operating cam, the bob-weights
and the points box and also the (worn) top bearing. Their view is
that it makes no sense to fit fancy electronics which would be triggered
by the old cam, which with worn bearings and old bob-weight springs,
could have differing moments of velocity at various points in the
rotation. They provide two small strong magnets which slip onto
the drive pins which previously held the advance weights, and then
their ignition kit is simply bolted on. This is a very logical approach,
and although the basic system is Hall effect, an LED is also fitted
to allow simple static timing. Their kit for the MGBGTV8 will cost
£213.00 including VAT and postage. At the moment their kits
for the MGB and the TR6 have been on sale for some years and there
have been very favourable reports. The V8 version incorporates as
standard 16 different advance/retard curves (you can choose which
to use using the rotary dial on the base of the unit) and also variable
dwell control so that you can vary the voltage developed by the
coil. The electronics is also said to incorporate "spark balancing"
to equalise the performance between different cylinders. These units
are now available from SC Parts on tel 01278 457372.
See sequel on 123 Ignition system (Oct 07)
This company acquired all of the old stocks of distributors and
parts when Lucas withdrew from manufacturing. In the case of our
Specification 41394 their stock of parts is low so they will not
sell spares for you to do the rebuild yourself - you have to send
your unit to Bromyard in Hereford (Tel 01885 488488) for them to
rebuild it in their workshops. The current price is £181.56
plus postage and VAT and the workshop time is quoted as being 3
to 4 weeks, although they rebuilt one of mine in ten days when I
was in a hurry in 2003.
This Norwich company (Tel 01603 891209) has built up an excellent
reputation for their work on Rover V8s, many of which are used in
racing or for extremely fast road use. They offer brand-new Mallory
(American) distributors and you have to remember that even today
in this oil-starved world, more than half of all the cars sold in
America are V8s, so Mallory are in a very competitive market. RPi
have already sold over 1,000 Mallory units in the UK and they come
in two forms:
argument for these is that the voltage is shared equally between
the two sets of points and they suggest on their website that
a mileage of up to 20K miles is quite normal, but I have also
heard of various V8 owners having problems with these units.
On these units you can adjust the advance/retard curve and
the twin-point system provides an extra 10° of dwell time
which gives the coil a longer charge leading to a higher voltage
to the plugs. Currently this distributor is priced at £245
plus postage and VAT - this price including a high-voltage
coil and ballast resistor.
Unalite or Magnetic - these are complete electronic distributors,
ideal for racing and similar applications but rather expensive
at £375 plus carriage and VAT.
RPi recognised that many customers wanted to have brand new electronic
distributors but would try to avoid spending nearly £450 on
the Mallory Unalite, so they have just introduced their own range
(based on the Hall effect principal) to fit any Rover V8 engine
at £175 plus carriage and VAT. This new unit is not yet on
their website but has a heat-sink etc on the outside just like the
Group - the final solution
These people have also come up with a totally different way of solving
distributor problems - keep the thing there for the sake of appearance
and originality but take away most of its functions. This might
sound expensive and complex but the benefits in terms of the engine
always staying in tune, of better starting and running and of improved
economy mean that this "final solution" should not be
ruled out! Basically you would fit an ECU (electronic control unit
- a totally normal part on all modern cars) - together with sensors
for crankshaft position, throttle position, water temperature, and
air intake temperature together with lambda sensors in each exhaust
manifold at the point from each bank where the four pipes have joined
into one. These lambda sensors detect the amount of oxygen and other
gases in the exhaust so helping you to tune the mixture very accurately,
whilst tuning the ECU allows you to adjust your advance/retard curve
for maximum torque or for maximum power etc. Assuming that the distributor
is retained just for sending the voltage (as controlled by the ECU)
to the plugs and that the standard coil is also kept in service,
then the cost of the parts will be around £700 plus VAT, however
fitting the various sensors will for most of us require professional
help, followed by a rolling road session to map the ECU properly
so the total cost will probably be near to £1,500. For more
information contact SC Parts on tel 01278 457372.
initial posting on the V8BB from Gordon Hesketh-Jones brought a large
response from fellow members including:
Chris Armitage: For anyone pondering this I would refer them
to my V8NOTE316. In my view the way forward is the Mallory dual point
distributor. I fitted it a few years ago, immediately noticed a massive
improvement in running quality, and have literally not touched it
since! It is a wholly more substantial and better engineered item,
but in character with the rest of the car in that there's nothing
electronic involved, i.e. if it should ever fail the chances are you'll
be able to fettle it by the roadside.
Gordon Hesketh-Jones replied: Yes I did read your V8NOTE316,
but the trouble is, there are two separate MGBGTV8s here in West Cornwall
whose consistent misfire problems were only cured once they got rid
of the Mallory Twin-Contact distributors, so I am not keen to go down
that route I would class you as one of the lucky ones.
Mike Russell: I ran a BGT for 10 years with relatively little
trouble with points other than a general reluctance to start but I've
found that goes with the territory. I bought my current MGBGTV8 in
1997 with a Lumenition unit fitted, but the records I inherited do
not include a receipt or date when it was fitted. However it has performed
faultlessly for 10 years and I have never had occasion to 'fiddle'
with it. Turn the key and off you go. Mind you I do not clock up the
kind of mileage Gordon does, but if I bought a car without electronic
ignition it would my very first purchase closely followed by halogen
headlights and then a battery conditioner unit.
Graham Cornford: My MGBGTV8 has the original Lucas distributor.
I have a Pertronics electronic ignition system that fits totally within
the distributor cap with the exception of a lead to the coil which
has been changed to a Pertronics flame thrower coil. I never touch
the distributor. It always starts well even after a long layup. The
only problem was that at first there was a problem with the tacho.
It read backwards. That was solved by Speedy Cables. I know of another
later unit that has been fitted to a V8 and that one had no trouble
at all. It was realistically priced, about £50, unobtrusive
and works well. It came from the USA but I believe that Pertronix
have an agency in the UK. It is thoroughly recommended. The plug points
gap though has been increased to 45 though to make the spark really
Tim Edmonds: I have had a Lumenition system fitted for over
15 years to my MGBGTV8 as I also got sick of replacing the points
and the plastic adaptor had failed.
Hesketh-Jones responded to Mike Russell and Tim Edmonds: My problem
with the Lumention unit is the THREE of them have failed on me and
I really don't want to try "fourth time lucky"!
I would like to confirm Graham's comments as I also run a Factory
MGBGTV8 with a Pertronix Ignitor 2 electronic ignition coupled with
their Flame Thower 40,000 volt coil having removed the Luminition
unit. Currently it has covered 10,000 miles without a hiccup, starts
first time every time no matter what the condition. I had the earlier
unit fitted to an 1800 Roadster which covered more than 30,000 miles
without the distributor cap ever being removed. I think that this
is one of the best and neatest units on the market and at approx £50
to £60 is excellent value for money with a two year guarantee.
I have the original publicity blurb if anyone is interested. I purchased
both items through www.lbcarco.com/
Armitage returned with additional information regarding his
advocation of the Mallory distributor I have to confess that I have
mine set up in single point mode rather than dual point! I bought
the Mallory unit from RPM in Norwich, who have detailed instructions
on how to set it up on their website. Lacking a dwell meter, I found
this a bit daunting so disconnected one point and set up the other
as per a standard distributor. When I have more time and a dwell
meter I will set it up 'properly'. But even with the single point,
the size of the contact set is at least double that of the flimsy
Lucas item, and is clearly much better made, and the condenser is
again at least twice the size of the Lucas equivalent. Everything
is engineered on a grander scale, there is no slack in the mechanism
and the amount of advance is adjustable.
If the examples Gordon has quoted suffered from miss-fire I would
venture to suggest that maybe the dwell of the 2 point system was
not set up properly. If you operate in single point mode then there
is no feasible difference to the Lucas set up, except that the spark
happens at exactly the right point in time rather than scattering
all over the place. This was first apparent to me when the strobe
light indicated a rock steady setting rather than the blurr previously,
and this was reflected in the running quality. Get a Lucas distributor
in one hand and a Mallory in the other and you will never want to
put the Lucas one back!!
Chris then added he has no connection with Mallory or RPi and the
distributor is the only non-standard bit of the car. He used to
have an optical Luminition system on the previous Lucas distributor
but it suffered from misfire which went away when I replaced the
manual points. Finally, replacing the points with electronic ignition
on the Lucas distributor is only solving half the problem, as you
still have all the slop in the mechanical advance mechanism and
have to keep replacing the vacuum advance unit frequently - or at
least I did.
James Heaton added some comments: I have done about 60,000m
in my MGBGTV8 in the last two and a half years. The car came with
Piranha which died after about 25,000 miles on a wet, dark, wintery
night - as they do. I fitted a Lucas Opus 35DLM8 bought from Rimmers
and as I was away abroad on business, took the opportunity to upgrade
the oil pump to increase its capacity and pressure. I have run with
the Lucas Opus for about 35-40,000 miles without a problem. Having
said that the first unit received from Rimmers was faulty but they
happily changed this. I know that Clive Wheatley sell these and
know he would not do so if he had doubts about them. My previous
car was a Rover P6B, 3500S fitted with Lumenition and this worked
faultlessly for three years and 90,000miles.
Ph-A Kaplan from Antwerp in Belgium added: I have been on
the side of the road on Saturday night so I changed to Lumenition.
It works faultlessly. Done 6,000 miles since with a mixture of weekends
and mixed urban/highway motoring. He added a comment on the oil
pump: I am quite interested in supersizing the oil pump. I do not
know what the exact pressure should be, but as I have a heavy right
foot and my V8 is quite willing to perform, I would like to go for
a larger pressure/ flow, so as not to harm her. Could you advise
me what/where to buy from?
Hesketh-Jones responded: Reference the query from Ph-A Kaplan
about oil pressure and whether to change the oil pump, the V8 engine
will only have had a pressure of 42psi when brand new. If your engine
is showing better than 39psi at say 3,000rpm when hot, then it is
OK. Fitting a high-pressure oil pump will not help the bearings.
To be continued . . . See V8NOTE379