6 replies to this topic

[mbolt998]

Recently and gradually my car started doing something I have noticed before years ago, but when went away completely after I "recommissioned" it. What I'm talking about is how, when cold starting, it fires enough to disengage the inertia pinion starter, but then immediately dies. Not a huge problem. You try again a couple of times and off you go. Once it's running it seems fine.

 

Not sure what was causing this I thought I'd try one(ish) thing at a time. First I checked the timing, and it seemed about right, but I had forgotten to disconnect the vacuum pipe when I measured it, so I think actually it was a bit retarded (which I think would make sense if the points were closed up a bit-- they would open a bit later than they should). My theory is that might be the cause of the problem.

 

I cleaned the points, reset the gap, cleaned up the rotor arm a bit while I was there, and checked the timing. It was now somewhat advanced, so I set it to what it should be (I use 8° BTDC at 1000rpm vacuum pipe disconnected). Then it seemed to start fine the next morning without the firing-then-dying behaviour.

 

I also then checked the spark plugs, and they were fine. Cleaned them up a bit, checked the gap, and put them back.

 

Would a late spark cause that kind of starting behaviour? On vintage cars you actually retarded it to start them so from that point of view it seems the wrong way around. But I think you were usually using a hand-crank on those.

 

It's quite possible I'm completely wrong and am also interested in alternative theories :)

[unburntfuelinthemorning]

I found it a common occurrence with inertia starters.  The engine would fire briefly which sped the flywheel up and disengaged the starter.  More of an annoyance than anything particularly wrong.  I guess it happens when one cylinder fires but the other don't.  I have a pre-engaged motor now so it just cranks until the engine starts.

[Spider]

I can't see it being the vacuum advance (or lack thereof) as there is next to no vacuum on the post at cranking speeds.

 

Often what's needed is a good 'hot' spark. With all other standard parts, this is one place an electronic set up can shine. Points don't switch 'clean' as compared to an electronic set up, points switch slow and open a few times (bonce) when examined by an oscilloscope. Electronic sets up switch clean and instant, thus driving  the coil in a better manner. Certainly, the modules that replace points are an improvement however the likes of a CSI Distributor is night and day over points.

[alpder]

Could be that the starter is too weak to 'keep up' with the engine at its first splutter, so disengages early. Might be worth looking at brushes, free-ness (or otherwise) of the pinion on the shaft, battery, battery cables, solenoid, earth-strap.

[gazza82]

One simple mistake I've seen is the coil wired backwards. The spark isn't as strong.

Older coils are marked SW (switched-live) and CB (contact breakers) which work fine on positive earth cars. SW is actually the -ve side, CB is +ve. Can get confusing if used on a negative earth vehicle.

(I have a fried who owns that particular T-shirt!!)

[mbolt998]

I can't see it being the vacuum advance (or lack thereof) as there is next to no vacuum on the post at cranking speeds.

 

Often what's needed is a good 'hot' spark. With all other standard parts, this is one place an electronic set up can shine. Points don't switch 'clean' as compared to an electronic set up, points switch slow and open a few times (bonce) when examined by an oscilloscope. Electronic sets up switch clean and instant, thus driving  the coil in a better manner. Certainly, the modules that replace points are an improvement however the likes of a CSI Distributor is night and day over points.

Thanks. So that would imply that it was cleaning the points that made the difference, rather than resetting the timing.

[Spider]

Thanks. So that would imply that it was cleaning the points that made the difference, rather than resetting the timing.

 

Quite likely, though setting the timing would also help, if it was a fair way out.