240 General: Ignition problem

[Bob 1967]

Hi all. Been a while.#
Been driving fine for a good while .Last week took it for a spin with no issues. After parking up in a car park (about an hour later)it started having problems.
it kept cutting out on deceleration. Not fun. Wouldn't idle.
I decided to check static timing , it was about TDC. tried moving Distributor but it was as far as it could go.(Dwell and gap is correct.)

I did a while ago try a electronic points (hot spark) this was firing at 30btdc, so I removed it and went back to points.

I believe the distributor when "out of range" it can be pulled out and moved one tooth. Problem is I'm not sure which direction. Can anyone help.
B21A Pierburg Carb , Points ignition.

[Othen]

Originally Posted by Bob 1967

Hi all. Been a while.#
Been driving fine for a good while .Last week took it for a spin with no issues. After parking up in a car park (about an hour later)it started having problems.
it kept cutting out on deceleration. Not fun. Wouldn't idle.
I decided to check static timing , it was about TDC. tried moving Distributor but it was as far as it could go.(Dwell and gap is correct.)

I did a while ago try a electronic points (hot spark) this was firing at 30btdc, so I removed it and went back to points.

I believe the distributor when "out of range" it can be pulled out and moved one tooth. Problem is I'm not sure which direction. Can anyone help.
B21A Pierburg Carb , Points ignition.

Hi Bob,

If your motor car has been running well then it isn’t really possible for the orientation of the distributor on its splines to have suddenly changed, so check a few other things first. It would be really helpful to check the timing you have now using a strobe - they aren’t expensive, or perhaps you could borrow one. If that does indeed show the ignition timing is too retarded then it would be worth checking the camshaft timing belt to make sure the 3 marks still align at TDC on the first cylinder. It is more likely that the auxiliary shaft is one tooth (from memory 6 degrees) out than the distributor is on the wrong spline. It is quite easy to get the auxiliary shaft misaligned when changing the belt as the mark on the case is hard to see.

If that much checks out then it is possible to move the distributor body forward. I’m guessing you removed the distributor to fit an electronic ignition set up, so just do the same. It will have to go back with the distributor body turned anti-clockwise by one spline (so turned opposite to the rotor arm’s direction of rotation to advance the ignition). Mark the distributor’s current position with a couple of punch marks or some Tipex so you can check the alignment has moved in the right direction afterwards.

The RB has the same engine as your motor car (B21a) but has Bosch electronic ignition from a post 1984 model (fitted by a previous owner). I find this excellent in that once set up correctly it never needs any attention. I’m wondering whether it might be worth re-fitting your electronic ignition distributor, but on the correct spline so the dynamic advance is 15 degrees (from memory)?

Alan

[Stephen Edwin]

Originally Posted by Bob 1967

Hi all. Been a while.#
Been driving fine for a good while .Last week took it for a spin with no issues. After parking up in a car park (about an hour later)it started having problems .....

So. What can have "happened" during that time ?? Something that was on the verge of "failing" finally failed? It's a bit of a mystery but above all, keep checking the basics and assume nothing. Beware of changing or adjusting anything especially do not do multiple changes or adjustments ... therein lies confusion and expense.

Good luck.

EDIT Had you done something like filling up with different petrol? &c. &c. Some mysteries have simple answers ...

Stephen

.

[Clifford Pope]

If it's running on traditional points then the easiest way to check the timing is simply by watching the contacts as you turn the engine by hand. I find I can hear the spark, but otherwise just use a bulb and a bit of wire.

The usual cause of sudden poor running is a failed condenser. Is yours a new red one from the Distributor Doctor?

If it running before this happened then it can't be the distributor jumping - don't fiddle with it. But it could just possibly be that the clamp bolt isn't tight and the distributor has moved.

[Othen]

Originally Posted by Othen

Hi Bob,

If your motor car has been running well then it isn’t really possible for the orientation of the distributor on its splines to have suddenly changed, so check a few other things first. It would be really helpful to check the timing you have now using a strobe - they aren’t expensive, or perhaps you could borrow one. If that does indeed show the ignition timing is too retarded then it would be worth checking the camshaft timing belt to make sure the 3 marks still align at TDC on the first cylinder. It is more likely that the auxiliary shaft is one tooth (from memory 6 degrees) out than the distributor is on the wrong spline. It is quite easy to get the auxiliary shaft misaligned when changing the belt as the mark on the case is hard to see.

If that much checks out then it is possible to move the distributor body forward. I’m guessing you removed the distributor to fit an electronic ignition set up, so just do the same. It will have to go back with the distributor body turned anti-clockwise by one spline (so turned opposite to the rotor arm’s direction of rotation to advance the ignition). Mark the distributor’s current position with a couple of punch marks or some Tipex so you can check the alignment has moved in the right direction afterwards.

The RB has the same engine as your motor car (B21a) but has Bosch electronic ignition from a post 1984 model (fitted by a previous owner). I find this excellent in that once set up correctly it never needs any attention. I’m wondering whether it might be worth re-fitting your electronic ignition distributor, but on the correct spline so the dynamic advance is 15 degrees (from memory)?

Alan

I've been thinking about this problem Bob. It would certainly be worth checking your ignition timing with a strobe, and then making sure you are turning the distributor the right way to advance the ignition.

If the ignition is indeed too retarded, and you have run out of adjustment to advance the distributor any further, then it would be a pretty simple matter to correct. If you removed the distributor to swap to the electronic ignition system then it is possible that you have put it back one spline out of alignment, but that is somewhat unlikely. The splines on the bottom of the rotor arm shaft are quite coarse (from memory there are only about a dozen - so each would correspond to about 30 degrees of arc), it is unlikely that you got the timing 30 degrees out and the engine still ran.

I think it more likely that the auxiliary shaft sprocket is one tooth out. Has the cam belt been changed recently? As you may see from this photo, it is easy to miss the alignment mark on the can belt cover:



... and that sprocket has many more teeth (perhaps 40, so each would be something like 9 degrees), it sounds much more plausible that the distributor could be 9 degrees out than 30.

There could be other reasons for the poor running of course, which is why I think it would be best to test the timing with a strobe first to make sure it really does have no advance.

I hope this helps.

Alan

[Bob 1967]

Thanks to all for replies
Hi I never removed the distributor, the electronic was a straight swap for points.
The alignment marks on the pulley lines up with notch on top of engine
( removed silver cover for access)
Condenser is fairly new (less than a year) Bosh.
The distributor body needs to rotate anti clockwise but is at max .
I have a strobe light .
Its just very strange , will run on choke but tick over is too fast.


Alan , is there a mark on bottom pulley too?
If so I'll check it tomorrow. Too bloody cold out now. Brrrrr.
It could really be anything stopping it idling but I want to make sure timing is done first.
Then Ill try check vacuum hoses.

[Bob 1967]

Like Solomon Grundy Did the left side , Right side is not bad , but Ill do it next spring.

[Othen]

Originally Posted by Bob 1967

Thanks to all for replies
Hi I never removed the distributor, the electronic was a straight swap for points.
The alignment marks on the pulley lines up with notch on top of engine
( removed silver cover for access)
Condenser is fairly new (less than a year) Bosh.
The distributor body needs to rotate anti clockwise but is at max .
I have a strobe light .
Its just very strange , will run on choke but tick over is too fast.


Alan , is there a mark on bottom pulley too?
If so I'll check it tomorrow. Too bloody cold out now. Brrrrr.
It could really be anything stopping it idling but I want to make sure timing is done first.
Then Ill try check vacuum hoses.

Hi Bob,

If the distributor hasn't been removed then the splines can't really be out of synchronisation - if it had been 30 degrees out the motor would never have run in the past. If you did want to check that installation the procedure is pretty simple though:



... I don't think that is the problem though.

Regardless of the rough running, the ignition advance should not be zero, so that needs checking first. A strobe is easiest and best - the mark on the bottom pulley is a notch on the pulley - it is best to highlight it with some Tipex or white paint - you will see it next to the timing scale:



That is also the TBC mark you will need to check the cam belt alignment later... but the first thing to do is to check the timing with your strobe light. The TBC mark should be at 15 degrees BTDC with the vacuum advance disconnected. If the distributor doesn't have enough travel to achieve that then the cam belt alignment is probably wrong.



Checking the cam belt alignment only takes a few minutes - all three of the marks - bottom pulley at TDC, camshaft pulley next to the mark on the cover:



... and auxiliary shaft next to the mark:



From memory I think you have to remove the plastic cam belt cover for access, then temporarily re-fit it to ensure the bottom pulley is at TDC, then take it off again to check the other two marks.

If the auxiliary sprocket isn't right then you will have to slacken the tensioner, slide the belt off, put it on the right place and so on. This only takes a few minutes. Once you are sure the belt is set up correctly the distributor should sit roughly in the middle of its adjustment range.

Check the timing again with your strobe at this stage - you should be able to achieve 15 degrees BTDC without the distributor adjustment being against its stops.

There could of course be other reasons for the poor running - but if you aren't sure about the timing I'd make sure that is spot on first and so eliminate that as a suspect.

The first inch (or there about) of the choke cable's stroke doesn't operate the choke at all, it just opens the throttle a little bit to increase the tick-over speed. Once you have checked, and if need be adjusted the timing, distributor/cam belt then if the motor still isn't running properly we'll start looking for some other problem (other ignition parts or the carburettor).

I hope it warms up enough to have another look at the motor car soon (it is pretty warm (for December) here in England).

Alan

[Bob 1967]

I checked the points with a meter , its an old model but it works.

[Bob 1967]

Thanks again Alan.
I suspect it is the Auxiliary Belt , It's the one thing( Ignition wise) I haven't checked. it was sunny and 5 degrees ,with a bit of wind chill for good measure.
When its warmer , it's usually raining!
Bob.