435
Pertronix electronic
ignition queries
Pete
Thomas was having a V8 distributor serviced prior to installing a Pertronix electronic
ignition set up as a replacement for the original contact breakers. He had a few
queries and sought help from the V8 Register saying any guidance you can give
regarding this will help and Bob Grieves responded.
(Aug 11)
Bob
Grieves responded saying "I fitted the Pertronix II with a FlameThrower
coil in 2009. The unit failed last December and was replaced free of charge by
Pertronix, however as my car is running fine on the standard set up I have not
refitted the new unit". Bob's replies and later Pete's feedback are below:
Will the standard fit
V8 tachometer still work with the Pertronix system?
Pete has a ballasted
system fitted 1.5 ohm coil as I think all Factory MGBGTV8s were like this. Bob
replied that his tachometer worked fine with the Pertronix system. Pete subsequently
confirmed his tachometer worked fine with the Pertronix system installed.
Is the V8 tachometer a Current or Voltage sensing type on an MGBGTV8?
Pete has a ballasted system fitted 1.5 ohm coil as I think all Factory
MGBGTV8s were like this. Bob replied that his tachometer worked fine with the
Pertronix system. Pete subsequently confirmed his tachometer worked fine with
the Pertronix system installed.
As the system is ballasted will this
need re-wiring as well?
Yes, I ran a new cable from the ignition side
of the fuse box
Do I need to find the ballast resistor in the loom
and remove it as the Pertronix Ignitor will need a good 12volt supply?
Bob replied "No, leave the ballast feed intact, otherwise you cannot refit
the points and condenser set up. When my unit failed, I refitted them to see if
that was the problem and it took about 15 minutes. You will also need to remove
the small bolt that adjust the timing and store that with the spare set of points".
Following his installation Pete confirmed he also ran the red cable from the Pertronix
unit to the ignition side (white cable) on the fuse box. He left the ballast feed
intact as instructed by Bob Grieves.
Do I need a new coil?
Bob replied "Yes, you will need a 12v coil and I suggest you use the Pertronix
FlameThrower".
Bob Grieves then referred to some problems he had
when he first fitted the new Pertronix unit. It turned out to be because they
had sent me the wrong sensor for the 35D distributor on the MGBGTV8. Correct box,
wrong unit! You also need to ensure that you have a good earth from the distributor
to the battery, Bob attached (see below) some comments sent by to him |
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at that time by Carl Dudash
of Retro Rockets in the US which are useful.
Bob,
Just want to be sure you have a 35D8 distributor. You must turn the points adjust
screw about all the way in so that the module is about .020-.030 away from the
magnet sleeve. However, the module and sleeve should never touch. If you have
a ballast resistor to the coil, the red Pertronix Ignitor wire must be connected
to the 12v side of the resistor and not to the side going to the coil. The Ignitor
II likes a full 12v for best performance.
Finally be sure you have a good earth. If you don't, the Ignitor II will not fire.
Check the resistance between the breaker plate in the distributor and the battery
negative post. It must be less than 0.2 ohms. Anything
more than that indicates a bad earth. Check for corrosion or loose connections
in the earth circuit. It is a bit more complicated to test an Ignitor II because
the magnet sleeve must be rotating for it to fire. If the above suggestions still
do not result in spark you can send back the module and magnet sleeve to the warehouse
for testing. It is most unusual for an Ignitor II to be faulty right out of the
box since they receive 100% testing before shipping from the factory. Please let
me know how you make out. We want to be sure you are satisfied with the system.
Reliability of the Pertronix system
Bob also mentioned he had been
assured by Carl Dudash at RetroRocket that the failure of their Pertronix units
is very rare but Carl did say that if the unit is subjected to any voltage above
16v, then the unit could be damaged. This may occur by either a faulty alternator
or if a high boost charger is used to start a car with a flat battery. That type
of boost charger is used by the vehicle recovery companies and the booster can
put up to 24v through a system. This was not the case with the failure Bob had
experienced as the alternator is giving 14.5v as stated in the manual.
Intermittent misfire
Bob also felt the main problem with the intermittent
misfire he had was caused not by the distributor but by a bad earth from the engine
to the chassis. So far as Bob knew the engine in Bob's MGBGTV8 had not been removed
for a number of years, if ever, so the earth strap had almost certainly not been
disturbed, but on measuring the resistance stated in Carl's email Bob found it
was out of range. He also found the earth strap to be in poor condition, so he
added a second earth as the original was difficult to replace, and this bought
the resistance down to 0.01ohms. Carl also asked for the resistance to be measured
between the distributor plate and the earth post on the battery, as you will appreciate
not an easy task on an MGB of any type. So Bob measured it between the distributor
base plate and the oil filter housing. Since then the misfire has completely gone
- touch wood.
Pertronix installation instructions
Bob has
supplied copies of the installation instruction provided by RetroRocket and these
are available on the V8 website. More
See our earlier V8NOTES on Pertronix
systems for the MGBGTV8:
V8NOTE379 More on V8 distributors by
Gordon Hesketh-Jones. More
V8NOTE365
Distributor options for the MGBGTV8 by Gordon Hesketh-Jones. More
Pertronix Ignitor website
www.pertronix.com/prod/ig/default.aspx
See our Pertronix gateway webpage |
