jerking under load

[xpress]

Car started jerking under load.

First a little now quite a lot. Grr could it be points, condenser? Fuel? Please advise.

[katy]

First guess would be spark plugs, second would be condenser.

[chrisryder]

try those, then my third guess would be coil...

even if it is supposedly never the coil...

[minor65]

my first guess would be the points

[xpress]

Lol I regapped the plugs, slight improve but the jerking reappeared. Could fuel pump points do it? I can't find the red spring bit of my replacement ignition points! Would fuel filter be so intermittent as jerking seems? Or could it be timing, what bolt do I undo to move the distributor timing? I checked spark It's healthy not too sparky. I just put new condenser on there, will go back to old see if it improves!

[bmcecosse]

It's 'never' the coil. But it could be loose connections...... Sticky piston in the carb??

[xpress]

How do I sort that, shall I take the metal bottle off and clean it up with a clean rag and metal polish?

[les]

You seem to be having some real bad luck with this car, personally in view of the ongoing problems, have you given any thought to renewing the critical service parts one by one, and start fresh? There are not too many. Points , condenser, plugs, ht leads, pump points, carb jet and needle, maybe float etc. This way you needn't keep going back over things and with the correct adjustments you should have many trouble free miles ahead.

[xpress]

Sounds like a good idea, I can keep the rest as spares. What do I need to replace on the float?

[Neil MG]

Sounds like it may be the distributer not advancing properly.

[Dryad]

Try reading this thread, it worked for me; http://www.mmoc.org.uk/viewtopic.php?f=4&t=36816

[xpress]

Burn mark on right edge of rotor arm. Do you need to unclamp the two big bolts holding dizzy down and turn it clockwise by the same amount of area measured from the edge of rotor arm to the middle? If you retime the engine doesn't it put the contacts within good range of the rotor arm anyway?

[LouiseM]

Do you need to unclamp the two big bolts holding dizzy down and turn it clockwise by the same amount of area measured from the edge of rotor arm to the middle?

Sorry but don't understand what you mean by this Are you talking about how to set the timing?

You mentioned before that you had a Haynes manual. Have you looked at it as it has a handy 'trouble shooting guide' at the end of each chapter which lists symptoms, likely causes, and explains how to fix them. It explains clearly how to replace points, condensor, low tension lead and rotor arm and also how to set the timing. As Les has already mentioned, best to work through one thing at a time to eliminate the causes of your problem - perhaps start by replacing the rotor arm? If you start undoing bolts that you don't need to you could just end up with another problem!

[Dryad]

The bit I was referring to in the thread I suggested was this;

"In despiration I took the cap off, and had another look. . . . The braded earth lead (replaced last year) that goes from the terminal to the points is slightly longer than the original and the loop of cable slightly sticks up. I re routed the wire, tucking it behind the condenser cable which I avoided innitally as I wanted to keep all the wires separated and not risk chafing the cloth brade on the advance mechnism' which was what happened to the original......Hey presto problem solved!!!! The spark for cylinder 1 was earthing to the cloth brade of the cable when under the load of accelleration! Hence loosing a cylinder. Not sure why it wasn't doing it at tick over???"

It worked for me too!

[Declan_Burns]

Check the static timing as described in your Haynes manual-page 81-it doesn't take long. I have had the pinch bolt on the distributor come loose and the symptoms match your problem-as mentioned above advanced timing.
Regards
Declan

[xpress]

Filed the points a couple times. Tucked the little l t lead out of the way it looked frayed. Gapped the slugs. Hey presto better pickup, acceleration and puffy missing under load gone. Loosened up two clamp bolts will mark position with tipp ex. Will.get another little pig lead, it looks frayed.

Thanks all.

[xpress]

set points gap after more jerking then misfiring! still misfiring. changed condenser back to old known one. cured.

what is it about new condensers? intermittent fault with a new one?!

at least It's ok now, points gap and plugs set.

[les]

Now leave it alone!!!!

[xpress]

lol until the next time something plays up!

ps. its advised to change the condenser with a points change and the new condenser hasn't lasted that long!

[bmcecosse]

Thank goodness it wasn't the coil........