Thread: MIsfiring ,too rich mixture, Need help

Thanks Philip,I tested coolant temp sensor and it was 2740ohms which is within range. I am going to get another set of spark plugs and try again.if that doesnt stir anything then I will pull the dissy out and find someone to test and rebuild it.

Thanks Philip,I tested coolant temp sensor and it was 2740ohms which is within range

The important test of the coolant sensor is when the engine is at operating temp when it should be 200-400Ohms, but at least it isn't open circuit.
Regards Philip A

Have taken the dizzy down to AFI and they advised that given it is throwing a spark there is no point in checking it.
My dilemma I believe, is that when the rotor is pointed to the No1 cylinder post of the distributor the star gear is NOT aligned with the pickup. This also applies to the position of the star gear at all cylinder posts of the distributor as the rotor and star gear are on the same shaft. If I could work out how to post a picture I would. The only way to alter the position is by way of altering the base plate of the pickup which is held in a position determined by the arm of the vacuum advance. My vacuum advance unit is proably stuffed in that it will not easily move inwards. The inward movement will slide the base plate of the pickup anticlockwise and is the only way that the base plate will change its position relative to the star gear.
Rotating the dizzy does nothing in relation to the star gear and the pickup that I can detremine.

My theory is that when the star gear passes the pickup it generates a pulse thru the amp to the coil and back to the distributor via the rotor button to the repective cylinder post...lead and the plug.
If this is happening when it should then the fuel is ignited and away we go.
If as in my case the pulse is generated from star gear etc when the rotor button has actualy gone slightly past the distributor post then would that not then result in a weakish spark and fuel fouling of the plugs etc. Happens to be what I have.
If anyone knows or can see where the star gear is in relation to the pickup when the rotor is pointing to a distributor post, this may confirm or disprove my theory. In other words is the point of the star gear aligned with the pickup when the rotor is at a cylinder post. If not by how much is it away and is it before or after the pickup module ( anticlockwise or clockwise)
Happy to hear any other theories

Peter , I today pulled down my new dizzy to modify it for fitment.

I noticed that the chopper wheel should have a peak immediately adjacent to the protuberance on the sensor as the rotor points exactly at the contact for the spark plug wire which is entirely logical. This is when the vacuum advance is full retarded ie at rest. It moves with vacuum advance. I carefully marked everything so I am sure it is correct.

I cannot understand how it could be otherwise unless you have removed the chopper and put it back in the wrong place, which would involve a lot of force, as there are 4nylon lugs under it and one is wider than the others so that it only fits one way.

Maybe the sensor has been fitted in the wrong place as it has some adjustment or the vacuum advance is seized?.
From your photo , it looks like the vacuum advance is seized at maybe more than full vacuum advance. Try pushing the pin/ plate clockwise and see if it moves the plate .

Regards Philip A

Thanks for your response Philip,
As you stated the chopper wheel will only go on in one position given the plastic seat and I have stripped this down and redone it half a dozen times trying to assertain whether there is another way. By taking the vacuum advance off it does allow further adjustment of the sensor plate but as you know the whole plate holding that is retained in only one position by the three screws and it only goes on in the one position.
I am trying to arrange to get Rupert out to have a look at it and hopefully identify where the problem lays.
Should have his assessment by the end of the week.

I recall that when I turned your centrifugal advance to check it, it moved correctly then let go and moved a lot more with a clunk.
Have you taken off the top of the distributor shaft at any time. Could you have put it on 90% (well not exactly ) out?
Regards Philip A

as you know the whole plate holding that is retained in only one position by the three screws and it only goes on in the one position.

Well yes the entire plate does, but what about the sensor? Did you remove that? I didn't as I assumed the air gap is correct and I didn't want to change it. But there is another hole in the baseplate around 90 degrees . I do not know whether there are alternate holes under the sensor.
Regards Philip A

The sensor plate is also resticted to movement clockwise due to the wiring and a smalll metal stopper on the underside. At least it is on this one. I did not take the sensor off the pickup base plate in any event and its movement is normally determined by the vacuum advance arm location.