V8 -> Ignition Problems

Jorgenson

Member
I have a P6 v8 Mk1 with a 5 gang r380 installed.
no matter what ignition system I had installed in recent years (mallory unilite, sd1 or contacts) it worked badly! after a few minutes the car begins to jerky. the ignition partly partially altogether and then comes again. I have EVERYTHING (sparks, cables, distributors,
ignition coil, balast-resistor, tachometer, ....) exchanged. how can I find the error?
best regards from germany
jorgen
 
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that would lead me to believe its something like a faulty ignition switch so you are randomly getting a low voltage to the ignition system or the fault is nothing to do with ignition, maybe you have a carb flooding or iffy fuel pump maybe a part blocked fuel pick up
 
I changed the ignition switch, but the problem is still there :-( how can I measure this? how high does it have to be voltage on the ignition coil (+) which comes from the ignition switch?
 
it might be worth checking the voltage present at the coil with the ignition on, a ballasted system will have about 9volt at the coil +
 
there are much more, there are 12.15 volts. is that a problem?
I have a ballast of mallory when i send + over the resistor to the coil this changes the the 12.15 v at the coil not
 
the purpose of a ballast resistor is to avoid volt drop causing a weak spark when cranking the engine.

what you do is have a 9 volt coil which when the ignition is on is feed via the ballast to cut the ignition voltage down to 9v, when you crank the engine over the ballast is bypassed so the coil still gets 9v when the starter works.

if you have a 9v coil and are feeding it with full battery voltage all the time you can overheat it, not to mention burn out points and condensers and possibly even overload electronic ignitions
 
the purpose of a ballast resistor is to avoid volt drop causing a weak spark when cranking the engine.

what you do is have a 9 volt coil which when the ignition is on is feed via the ballast to cut the ignition voltage down to 9v, when you crank the engine over the ballast is bypassed so the coil still gets 9v when the starter works.

When the starter is cranked you get a 12v supply to the 9v coil.
 
When the starter is cranked you get a 12v supply to the 9v coil.


in theory yes, but volt drop caused by the starter means the coil often wont see full battery voltage, but it means whatever it drops to the coil will see enough to give a big fat spark
 
I have the coil installed quickly and drived 2 kilometer (ah sorry 1.3 miles ;-)). mutch better ! no jerks anymore.
tomorrow I make a longer ride. thanx and good night


ps: the car is an auto to manual conversion. and i found a workaround cable from the ignition switch to the magnetic switch of the starter motor. perhabs it could be also a part of my problem :-(
 
years ago one would have had system checked on a 'sun testing/tuning' station that nearly all major garages had. this could pick up many faults such as wrong voltages. plug issues.leads etc a sit was designed to do so.
todays modern electronic cars use a plug in computer ( not 100% fault finder -still need a good technician) is dizzy ok? timing will make a difference as would cap tracking out etc. are we sure we don't have a fuel issue here too?
 
the problems seem to be solved & what i have do:
-change ignition switch ...now the car has 3 keys :-(
-change distributor to sd 1 type
-change coil to mallory promaster 30440
-install an additional ballast resitor ( is that required ????)
-fix cable problem ( ignitionswitch - starter motor )
 
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