40 replies to this topic

[dklawson]

I have limited documentation for the later cars (yes... a 78 is later to me) but the diagrams I have indicate your car should have a standard ignition system.  The coil and the wiring scheme you describe should work.

 

Miniman_78 said the two of you have set the ignition timing and firing order as I suggested and the engine won't fire.  Double check for spark by taking the plugs out and resting them (with plug wires attached) on the engine block.   Crank the engine on the starter while a friend watches the plugs.  If they are sparking, the ignition module is working.  If the timing and firing order is right, you might have a problem elsewhere.

 

You said the distributor was bought in the summer.  Was the engine running properly before the distributor swap?  If so... how long ago before the swap did it run correctly last time?  You mentioned that the engine backfires through the carb when it tries to fire.  If the timing is right and the plugs are firing, try tipping a thimble of gasoline down the carb throat.  After pouring the gasoline in turn the engine on the starter.  If the engine runs very briefly and then stops you have a fuel delivery issue to sort out.  Backfiring through the carb when the timing is right is a common symptom of fuel starvation.

[Dusky]

Is it a strong or weak spark by the way?
I can imagine that it wont spark if coil is starting to go bad orso? ( just a thought)

[dklawson]

Coils typically work or don't work.  Inside are a handful of windings of large diameter wire (the low-tension circuit) and a large number of windings of very fine wire (the high-tension circuit).  The ratio of the number of large to small wirings determines the voltage the coil is capable of producing while the actual voltage at the spark plug is determined by the fuel/air mixture and the gap of the spark plugs.  When a coil is failing, they do tend to produce a weaker spark once the coil is hot (such as once the car has been driven a while).  However, they are not likely to give non-start problems when cold unless they are totally dead.  On cars with points, if the condenser is bad, failing, or missing, you can easily get a weak spark that appears orangish in color.  However, cars with electronic ignitions do not use a condenser.

[freaker]

hi thanks for the reply.

 

 

spark plugs have been hold against the block, while turning over and trying to start. 

 

the coil is also a brand new one delivered with the distributor, 

 

it ran with is old distributor wich had a ducelier ? on it was a strange setup and not very mini like, but was electric. i then decided to pull the head off to make it unleaded, around 5 years ago :)... and put a different head on it a 295 that i had converted to unleaded it never ran on that. so i gave up 5 years ago. so i  got it to my house last year, and started working on it again. loom was a mess, so changed that, and a few other bits, then decided as i didn`t find any decent info on the distributor i would change it with a new one, i asked help on here for this issue. and kernowcooper pointed me in that direction. and bought one and installed it. miniman_78 came over to help as i couldn`t get here to run, tried everything and then decided to pull the head, we had a suspicion the head didn`t give enough compression as it wasn`t skimmed enough. so we pulled it off, and then i installed a stage 3 head for a 998, wich shouldn`t give a problem i think ? 

the fuel first wasn`t getting to the carb, pump was stuck, so installed a different one, will recheck if its functioning tomorrow or this week. also will do a compression check on the engine. 

 

freaker

[dklawson]

OK, are you saying there is spark on all the plugs and that the firing order and timing is set as described earlier?  

 

The engine really hasn't run in 5 years or more and the head has been off at least twice.  Don't take offense but please check the following.

1. Adjust the valves.  Even if you did them before, check them again.  It must be done anytime the head gasket is replaced.
2. Re-check all the intake manifold joints and vacuum hose connections.  Make sure all the gaskets are seated and bolts fully tightened to eliminate any possibility of there being a vacuum leak.  If you have a servo, temporarily remove its hose at the intake manifold and plug the manifold hole.
3. Try the thimble of gasoline test suggested earlier.  It is a quick screening test to see if you have a fuel deliver problem.
4. By all means do the compression check you were suggesting.

If the car was parked with fuel in the carb 5 years ago there is a very good chance that all your ignition adjustments are fine but you may have a carb with a stuck float valve (preventing fuel from getting in) or a jet that is blocked with fuel gum/varnish.  What carb is on the engine?

[Captain Mainwaring]

Powersparks very much like full voltage for correct operation - the timing flies all over the place if they get low voltage during cranking. Put a meter on the feed during cranking and see what you get

[freaker]

tomorrow i will have my hands on my compression meter again. and will try and do the test. 

 

the carb thats on there is a standard hs4 one, i have bought it from turner carbs, a well known rebuilder of carbs in the uk. 

so that should be ok. 

no servo on it so no problem there, the airfilter isn`t on there but i suppose that wouldn`t cause a problem ? 

 

hopefully the compression test, will give any more information... 

 

will try and and measure the cranking voltage of the wire... 

 

freaker

[freaker]

if the cranking feed of the wire isn`t good, what would be the solution to that ? 

could that cause my not running issue ?

 

freaker

[Powerspark]

Hello to everyone.

I hope you don't mind me dropping in to try and help.

I have had a quick read through this thread so forgive me if I have missed anything but when we see this it is most likely one of about three things.

 

Voltage feed to the coil = is it a good feed from the battery i.e 12 volts etc..

Is there a ballast fitted but no ballast coil fitted = this can cause issues with the supply to the coil
Do you have the correct coil fitted = incorrect resistance can cause erratic spark (not so common) 3Ohms ideal for standard electronic less than 1.4 Ohms for High Energy

 

So please can you contact me on our email and I will try to locate your order and help from there but also if you can measure the voltage at the coil when cranking and see if you have a ballast or which coil is fitted form the markings if there are any.

 

I hope this helps and sorry for sticking my nose in.

 

Simon

[dklawson]

Hello and welcome!  It will be nice to have your input on the ignition system.  While it is great to help the OP offline by PM, posting your findings here will help others in the future.

 

In post #1 the OP said that he has a new DLB105 coil which is a "standard" 3 Ohm type.  In post #14 he said that the loom is new and is for a '78 which would be wiring for a standard ignition system (if the online documentation is to be believed).  So the ignition module should be powered by a full 12V.  In post #19 they confirmed that they have checked for spark at the plugs and if I am reading their post correctly... they have spark.

[freaker]

hi,

sorry for bit late reply,

the input is very much appreciated. we can all learn from this.

so a little update. i charged the batteryfull on saturday. the charger said it was full so i unplugged it.
yesterday evening i measured the cranking voltage at the white wire. with the ignition on. i had 12.34V.
but when i started cranking it dropped to 9.5 and 8.6v.

a new battery is already on its way. as i was thinking i would need 12v while cranking.

freaker

[dklawson]

Yes and no.  The coil voltage IS going to drop while cranking on the starter.  It is NOT going to stay at 12V.  It simply cannot stay that high when the starter motor is drawing a huge amount of current. 

 

People on many forums flame the ballast ignition system because of two things:  1) Lucas (in some applications) used the dreaded pink resistance wire instead of an external ballast resistor, and 2) Ballast ignition systems are harder to troubleshoot if you don't understand what they do and how they are supposed to work.  Regardless, the ballast ignition system was developed to address the lower voltage that is seen on the coil during starter motor operation. 

 

In your case, your car does not have a ballast ignition system but that should not matter.  Didn't you say you tested for spark by putting the plugs against the block and cranked the engine on the starter?  If you saw a spark under those test conditions... your problem is not with the ignition module or coil voltage.

[freaker]

yes we saw a spark,

but i disconnected the white wire from the coil. and measured between there and the body so ther was no coil inbetween them. that cable comes straight from the fusebox if i'm not mistaken. its there that i measured those voltages

yes we held the plug against the block and saw a spark.

freaker

[freaker]

i emailed simon and he is telling me as when i switch on my ignition and have 12v on the coil and while cranking it drops.
i have a resistor wire in my loom.

and that a wire running from my fusebox straigh to the coil would solve the issue.

the only thing strange is that i have a spark even with this....

freaker

[dklawson]

Again, yes and no.

 

Voltage measurements on coil (+) while cranking are not going to tell you what type of ignition wiring your car has and that is what Simon is eluding to.  If you want to really figure out if you have ballast wiring, do  the following.

1. Connect a jumper wire from the coil (-) terminal to earth. 
2. Switch on the ignition and measure the voltage from coil (+) to earth.

(NOTE:  That is jumper on the low side of the coil to earth, voltage measurement between the high side of the coil and earth).

If you measure 12V, you have a standard ignition system.

If you measure 6V to 9V, you have a ballast ignition system.

 

Do not forget to remove the jumper after these tests. 

 

You are always going to see voltage changes/drops on coil (+) when cranking.  Always.  It is just the way it is.  The test I just gave you will determine if there is a ballast reistor (or resistor wire) in the ignition system.  Since the test is performed without using the starter motor it will indicate what your car's wiring really is.

 

If you find you have 12V on coil (+) during the test above, you do not need to make a direct connection between the fuse box and the ignition module as Simon suggested.  If you find 6V to 9V on coil (+) in the test above then by all means connect your coil and the power wire from the ignition module to a switched terminal on the fuse box as he suggests.