9 replies to this topic

[Tomm]

Hello TMF,

 

I am hoping someone can help me out with an electronic dizzy problem I have found myself with. I recently bought a car with a 1275 motor, the engine does start and run but it is giving me a few problems which I am hoping someone can help me with.

 

I believe that the problem I have is that the timing on the dizzy is out, and I am ideally looking for some help as to how to correct this. I will detail my problem below and hopefully someone will be able to help me out.

 

The engine starts relatively well I would say and idles quite well, how ever as soon as you give the motor a bit of throttle it goes very lumpy, erratic and unresponsive, if you continue to give it the faintest bit of throttle the engine backfires through the carb which is how I have come to the conclusion that the problem is due to timing (sparking with the inlet valve still open?).

 

If this was a mechanical dizzy then I would start by twisting the dizzy cap until this problem stopped but I have no experience with Electronic Dizzys and am reluctant to touch anything just yet in case I do more damage than good.

 

Could anyone give me any advice as to where I should start, What the problem could be and how I could get rid of it? I could be completely off the mark with my diagnosis of the fault so any sort of pointers would be fantastic.

 

Thanks in advance for any help, Tomm

[Yoda]

You time an electronic dizzy the same as the old type. but first whip the top off to make sure nothing is loose. also worth checking the dashpot for oil. I would have thought if it was that far out of time to fire through the inlet, it probably wouldn't idle too well, but stranger things have happened!

[grumpy dad]

try to pull the choke out a bit as you rev it

you will get spitting back through the carb 

with weak mixture 

[Yoda]

Tis why i suggested checking the dashpot as this will give a very weak mix when you try to rev it, but will be ok on idle.

[Tomm]

I've popped out to the garage and can possibly post a bit of an update.

Dashpot oil seems to be present, I'm unsure on how to check the level but when I remove the screw you can see it and there is resistance when you screw it back in.

When I removed the screw it was not screwed in all the way flush? Is this correct?

I went to start the car and it won't idle at all now. Looking back the car would only idle with the choke all the way out, no mater how long the engine was running for as soon as you released the choke the car would stall.

The engine only started once I had manually primed it and would then not idle but die pretty much instantly.

Would this help indicate the problem?

[Tomm]

My dizzy cap is a fixed item unlike the other caps I have worked with.

 

Should I adjust the dizzy positioning by loosening the mounting bracket and turning it from here?

 

How would I know if I should advance or retard the ignition, is it a matter of turn it and find out?

[KernowCooper]

You need a timing light to set the ignition timing correctly,I'd be looking at why the car needs full choke to run indication a severe weak mixture.

 

If this is a car you've just bought I would start with the basics, engine tune and tappets and a compression check to see if its head gasket related and then start looking at the carb and manifold gaskets, you have to rule out the basic stuff first

Edited by KernowCooper, 17 November 2013 - 06:13 PM.

[dklawson]

Do not do anything until you give this some thought and answer a few questions.

 

When did the problem start?

Did the engine run properly before or is this engine/car new to you?

What has been worked on recently (no matter how seemingly unrelated)?

 

IF the engine ran well prior to this problem and you have not adjusted anything it is very, very, unlikely to be timing related.  Timing does not change or accidentally, suddenly get out of adjustment.  What does/can happen is that a car that sits for a long while or one without fuel filters can have fueling related problems.

 

As noted above by Grumpy Dad, a weak mixture can and will backfire out the carb when you put any load on an engine or try to rev it.  While sitting, carbs can gum up and the carb float valves can hang shut.  Either can cause the fuel level to be low in the bowl.  If you have an HS series carb you can easily check the fuel level by revving the engine until the backfires start, then immediately turn the ignition off and stalling the engine.  Remove the three screws holding the float lid onto the bowl, remove the lid and look at the fuel level.  

 

Normally you go through a complete electrical tune up before touching fuel adjustments.  However, if you have done nothing to alter this engine's timing, and if it ran properly until just recently, take a look at your fuel delivery into the carb first.

[Tomm]

You need a timing light to set the ignition timing correctly,I'd be looking at why the car needs full choke to run indication a severe weak mixture.

 

If this is a car you've just bought I would start with the basics, engine tune and tappets and a compression check to see if its head gasket related and then start looking at the carb and manifold gaskets, you have to rule out the basic stuff first

 

Thanks for the reply.

 

A compression test was carried out when I first got the car home, all results were in the same sort of area from what I can remember and seemed to be no cause for concern. I will how ever give this a second check.

 

 

Do not do anything until you give this some thought and answer a few questions.

 

When did the problem start? I bought the car running like this.

 

Did the engine run properly before or is this engine/car new to you? As above

 

What has been worked on recently (no matter how seemingly unrelated)? The rad hose blew the day I bought the car when it was idling. A new thermostat was fitted along with new hoses. The car continued to run in the same pattern once this was completed.

 

IF the engine ran well prior to this problem and you have not adjusted anything it is very, very, unlikely to be timing related.  Timing does not change or accidentally, suddenly get out of adjustment.  What does/can happen is that a car that sits for a long while or one without fuel filters can have fueling related problems.

 

As noted above by Grumpy Dad, a weak mixture can and will backfire out the carb when you put any load on an engine or try to rev it.  While sitting, carbs can gum up and the carb float valves can hang shut.  Either can cause the fuel level to be low in the bowl.  If you have an HS series carb you can easily check the fuel level by revving the engine until the backfires start, then immediately turn the ignition off and stalling the engine.  Remove the three screws holding the float lid onto the bowl, remove the lid and look at the fuel level.  

 

Normally you go through a complete electrical tune up before touching fuel adjustments.  However, if you have done nothing to alter this engine's timing, and if it ran properly until just recently, take a look at your fuel delivery into the carb first.

 

Thanks for the reply and for your help. I have answered the questions in your above quote.

 

Going from what I was told by the previous owner was he replaced the mechanical dizzy with an electronic one some time ago, he fiddled with it until he reached a stage where the engine started, a point to work from as such. Time ran short, priorities got in the way and the car was sold. I then bought the car with the problem.
 

Glad I left it as it was now!

[dklawson]

You said you did a compression test.  If the numbers were relatively even and "reasonable" then that is a good start.  However, did the radiator hose blow because it was old, brittle and cracked or did it look "OK"?  If the hose looked OK, even though you have done a compression check... borrow the tools necessary to do a leak-down test.  The leak down test will tell you if there is a leak into the water jacket that would explain the blown hose and that could very well be part of the running problem.

 

If you can contact the former owner, I suggest calling him and asking why he changed the distributor.  If he changed the distributor to address a running problem and the engine still runs poorly that suggests that it is a problem other than the distributor.  If on the other hand the engine ran OK but the previous owner simply wanted to change to electronic ignition... the problem could be timing or the advance mechanism in the new distributor.  It is also worth noting that the factory electronic ignition uses its own special coil that is neither ballast, nor non-ballast.  Others will have to tell you specifics about the coil required.

 

If this is an aftermarket electronic ignition, how is it wired (where do its wires connect)?  Also, what wires (all the wires) are on the ignition coil terminals?