Alfa Romeo Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
107 Posts
Discussion Starter #1
I've posted this on the forum for my car but I thought I might try it on this forum as well.

I've replaced the Marrelli Plex distributor and module on my Giulia Sprint GT with a 123Ignition distributor.

I have selected curve A and have a MEC723 coil with a primary resistance over one.

I set the static timing according to the instructions and replaced the spark plugs.

The car initially started fairly easily and seemed to be running well as I warmed the motor up. Then it just stopped for no apparent reason and wouldn't re-start.

After checking that there was petrol in the tank and that it was getting to the carbutettors, It occurred to me that it might have floodded so took the cover off the air intake chamber. It was pretty wet inside so I left it to dry out.

I have since tried to re-start the car several times (after slow charging the battery) and nothing.

There is a good spark coming from alll the leads but the enging is not catching at all and there is a fair bit of backfiring happening through the exhast and perhapse some spitting back through the carburettors.

The spark plug leads are definitely in the right order 1,3,4,2 clockwise and the rotor button is pointing to No.1 when the static timing mark is aligned.

The car was running reasonably well with the Marrelli Plex, except for some pinging, and as I said it initally seemed to be running well with the 123Ignition.

I'm am at a complete loss as to what the problem could be.

Can anyone suggest anything?
 

·
Premium Member
Joined
·
14,996 Posts
Make sure that #1 cylinder is at TDC on the compression cycle when the rotor is pointed at #1. If you remove the spark plug and shine a flashlight down the hole, you should be able to see the valves lifting on the non-compression cycle.

Are you using the correct timing mark when you set the static timing? Curve "A" is the Bosch ..006 curve. I think that the static timing point for that is about 5 degrees BTDC.
 

·
Registered
Joined
·
4,316 Posts
There is a good spark coming from alll the leads but the enging is not catching at all and there is a fair bit of backfiring happening through the exhast and perhapse some spitting back through the carburettors.
From a distance, the backfiring and spitting back you describe is an indication that the timing may be 180 degrees out of phase (ask me how I know :)). Are you sure you were at TDC? To be sure you need to make sure the cam lobes are pointing outward when the pointer lines up with the TDC mark.

The best thing to do is simply start over. Pull the distributor, make sure you are at TDC and then carefully align the distrubutor keyway with the slot in the oil-pump drive. (NOTE: the key and slot are slightly offset and it's essential to insure that both are in alignment.) Sometimes the key in an improperly installed distributor will jump out of the slot or even break.

If you do this, are sure the mechanical connections are right, and your car still runs poorly then the problem may be with 123's electronics. Just to be sure, you might reinstall the Marelli Plex and see if the same problem appears.
 

·
Registered
Joined
·
4,316 Posts
I kinda thought the 123 w/ hot coil would be strong enough to fire fouled plugs, Richard. But then it may not be. Change the plugs. :)
 

·
Registered
Joined
·
107 Posts
Discussion Starter #6
Thanks 180Out, I thought I was beyond such a rookie mistake. I must have taken the distributor out at some stage and put it back the wrong way (the plugs are new by the way).

Ive 'taken the car for a run with the 123 and it seems to have more torque down low but I am still getting pinging just below 3,000 rpm under acceleration.

I'm thinking I might try another advance curve (I'm using 'A' at the moment). I haven't seen much on the different curves so I'm not sure what to try. Does any one have any suggestions.
 

·
Premium Member
Joined
·
14,996 Posts
Curve A is docile. If you set the static at 6 degrees it will give only 23 degrees at 3000 rpm. My current set up gives me 32 degrees at that rpm. I am surprised that you are getting enough advance to create pinging. Have you checked the timing at full advance ? I ran curve A up to 40 degrees full advance on mid grade fuel with no problems and I have a high compression engine.
 

·
Registered
Joined
·
107 Posts
Discussion Starter #8
I have 200 psi in each cylinder and the thickness of my head is between 110 and 111 mm (as near as I can tell measuring it in-situ).

Is there a chart I can get my hands on showing the figures for all the 123 curves?
 

·
Premium Member
Joined
·
14,996 Posts
I have posted some of them. Do a search on my name and 123ignition and you should find them.
 
1 - 9 of 9 Posts
Top