Ignition problem....what have I done?

[berni29]

Hi There

My plus 2 was running with Lumenition on the correct distributor (41189) D4. I thought that the advance was coming in a bit early (weak springs?) so I swapped it for another distributor that I bought new from a very well known Lotus parts supplier. This was fitted to my previous plus 2 and had only done a few miles. It is a Lucas L1 (or so I was told, not sure about that though) and was one of a batch that the supplier had made up.

It has a few differences to the standard unit but is very similar. I have fitted the Lumenition but no spark from the plugs. I get one from the coil. With it all wired up and the distributor off the engine I can hear a click from the distributor whan I turn the gear and at the same time I get a shock through the gear. If I earth the distributor then nothing, no clicks nowt.

I cannot work out where the spark is leaving the system. How can it possibly get to the shaft of the distributor? The only possibility is that it is going straight through the rotor arm. That looks fine though. There is a small possibility that the rotor arm is not lining up with the contacts in the cap though when the spark is triggered. Would that cause the spark to leak to the shaft in the abscence of having anywhere else to go?

This is driving me nuts. Any help appreciated. Like so many before me, I now wish that I had left the damn thing alone!

Berni

[rgh0]

Berni

From your description it sounds like the lumenition is working and the coil is working but there is something wrong between the lead going into the distributor from the coil and the leads out to the plugs.

I suspect you may be correct and the rotor is not aligned with the terminals when the lumenition is triggered. Check the lumeniton trigger mounting holes have the same locations in the new versus the old distributor base plate. If the new distributor used a different points set from the old one then the lumenition trigger may be in a different location and you will need a different trigger.

If its not that the things to check if you have a mutlimeter

1. Check continuity with the omhmeter between the lead ends and the terminal inside the cap to ensure they are all in place properly.

2. Check resistance between the centre terminal on the rotor and the end it should be zero or about 5k Ohm if its a resistance style rotor

3. Check resistance to earth from the rotor centre teminal and ground. It should be very high in the mutli meg Ohm range

4. Check the centre carbon terminal is actually contacting the rotor properly

Rohan

[berni29]

Hi Rohan

Thanks for your help. I replaced the cap and rotor, and it seems to wrk fine now. One strange (to me) thing is that I get a small spark at the plug on each firing of the coil, and then a big one when I should do.

Also, it is spitting back through the carbs on gentle low rev constant throttle and on overrun. Its fine when driving up through the gears. I have it set at 10 deg BTC, and wonder if I should advance it a bit. I can hear no pinking. Before I had a timing light I used to advance till I could hear pinking under full load and then back off a bit. Maybe that method is better?

All the best

Berni

[type26owner]

If the spark plug wires are tied together they will tend to share the spark. It does this because with the flow of electrons there is a magnetic field generated also. When the field changes strenght either by growing or shrinking it tries to induce a current to flow in any other close proximity conductor. Best to keep the wires at least 1/4" apart from each other to prevent this effect.

The higher the intial voltage to jump the spark plug gap the worst this sharing effect gets. Best to also set the sprak plug gap to the recommended value which is 0.5mm (.020"). Only problem is none of the spark plug manufacturers offer a plug gapped to that size anymore. Smallest one is now .025".

The spitting is caused from the timing being too retarded or the mixture is too lean or both. If you've installed a 4" OD steel crankshaft pulley then be aware the timing mark is in the wrong place (retarded) by just about 8 degrees. This stupid pulley problem will cause it to spit everytime. I suspect this pulley comes from a Cossie and it's markings on the cover are in a different place by about with a wild guess about 8 degrees more advanced.

[type26owner]

Oh yeah, check to make sure the rotor is not rubbing against the cap. The plastic boss that the carbon wiper resides in is only about 0.5mm away from the rotor normally. If you add a magnet carrier or light beam splitter under the rotor it can displace it up enough so that gap is completely closed. One major clue that it is rubbing is if you can see the cap moving slightly sideways while the engine is running and also the spring clamps are hard to fasten on the cap! When that happens the rotor will short out through the plastic to the mainshaft in matter of hours or days.

Another problem is the electrical resistance of the aluminum posts in the dizzy cap goes up as they oxidize from the ozone. IIRC, aluminum oxide is an insulator and it will standoff about 1000 volts per .001" thickness of oxide layer. About on an interval of several hundred hours of usage you should scrap that crud off.

The original Lucas caps with brass posts are still available as NOS but are at least five times more expensive then the inferior aluminum ones.

[berni29]

Hi Keith

Many thanks for your comprehensive reply. You are 100% right about the rotor not seating fully with the lumenition splitter. That was happening with the first cap and rotor, but the replacement ones (slightly different type) are OK in this respect. I had the distributor out with the cap on and then off, and there was no difference in turning resistance. Also I set the plug gaps to .8mm earlier today. I will close them back up a bit

I will give the car another 8 degrees of advance and go for a spin!

Thanks again for taking the time to reply and sharing your expertise.

[berni29]

Hi

Back from the spin, showing 18 degrees now at idle, and things are much improved. Nearly all of the spitting has stopped the engine is less sluggish, but I still cannot provoke any pinking. By the way, I am defining pinking as the tinkling noise you get in top gear labouring the engine at 30 mph or so. I might try a bit more advance........

Thanks again

Berni

[type26owner]

You need to establish where TDC really is relative to your timing marks and be absolutely certain. This requires either a long reach 2" dial indicator or a piston travel stop which threads into the spark plug hole. Most parts vendors sell a cheap travel stop made for doing this test.

If you need further assistance just ask and I'll detail how by either technique it's done.

[berni29]

Hi Keith

Great idea for using a dial indicator. I did exactly that, and stopped at the highest reading on the indicator, having gone backwards and forwards a few times. Much better than my screwdriver down the plug hole method. My marks line pretty much up. I say pretty much, because there is no indentation on the pulley that I can see, only my white (paper corrector) mark. So the pulley may well be non - standard. There are four timing marks on the crankcase, and someone has put a white blob in between the third and fourth ones. I am not sure if that is significant! It is definately a lotus block.

Now that I know that my mark lines up with the first (lowest) mark on the block, does it matter about the pulley diameter? It covers some of the marks on the block.

What is wrong with the advance till it pinks method? Is it possible that the engine will pink on a motorway where I will not hear it, or is the test at low revs under load a good indication?

Many thanks again

Berni

[type26owner]

Berni,
You have the later series timing chain cover that was changed from three marks separated by 10 degree to the four marks like you have which spans 30 degrees total. The most clockwise mark is suppose to be TDC and align with an indentation on the pulley.

The pulley diameter does not affect this angular measurement. The original cast iron pulley is 5" in diameter so it's easy to tell one apart from the other. The 4" steel pulley just spins the waterpump and alternator/generator over faster by 20%.

Nothing is wrong with the 'power timing' method. You can find hidden hp if the timing is too retarded or advanced. Another 10 degrees total advance if it's retarded is good for about another 20 hp. The goal is to get the peak combustion pressure to happen right around 15 degrees ATDC.

[berni29]

Hi Keith

Well, after a bit more experimenting the engine wants to be at about 22 deg BTDC. That corresponds with the white blob on the timing cover, so someone has been there before me. Wonder why it is so far of standard? The engine is running really well now, so that is where it will be staying I guess. I did double check the setting by turning the engine by hand until I got a spark on No 1 in case my timing light was telling porkies.

Thanks again for the help.

Berni

[type26owner]

Berni,
Come to think of it maybe I'm wrong about the TDC marking on your cover. If you stick a pocket mirror down and have a closer look there is raised lettering cast into the cover just above the marks. Perhaps the second mark from fully clockwise one is actually the TDC marker. If that were the case then the paint blob on the cover would align to the correct idling timing. Don't assume all is okay!

I drove my car for years before I discovered the problem with the timing mark on the replacement 4" OD steel crankshaft pulley. 'Finding' another 20 hp was a delight and getting rid of the spitting to was a sweet bonus. That's what I get for assuming all was okay and not thoroughly checking the seemingly obvious stuff out too.

[mikefromengland]

my car is a +2 130.i use a 43d4 dizzy the timing is 12 degrees btdc.i i was using the aldon ignitor with it .what a load of pap that thing is.it gave me heaps of trouble.the ignitor in the same plane as the magnet on the cam is a dreadful idea.i got rid of it.i now use a standard coil with points and all problems have gone my car has never ran so well.so much for technology eh.