faltering engine

[bmcecosse]

It's NEVER the coil -put the original one back on......

[eth]

You are indeed correct, my original coil was never removed from the car I only momentarily changed the wires over to another for the purpose of elimination. It was a simple thing given the number of spares available to hand.

[eth]

One thing I did notice when checking the spade connections to the coil was ht pulsing through the low tension terminals, no where near enough power to make me jump but still quite noticeable. Is this normal? And no bmc I'm not suggesting my coils faulty, its NEVER the coil.

[bmcecosse]

Ok - so start to investigate the HT side - rotor arm/dizzy cap/HT leads etc pretty much in that order.....

[liammonty]

With any luck, when your friend lends you his spare ignition bits on Tuesday, you'll discover what the problem is. All that stuff is cheap to buy, should you need to.

[bmcecosse]

Yes - there is a highish volts pulse through the LT as the points open and the coil energy discharges. But it may be an idea to check/change the capacitor in case it is down on 'capacity'....

[eth]

I like your optimism Liam, unfortunately I don't share the same. Forgive my ignorance if I'm wrong bmc, do you mean the points capacitor/condenser? If so it doesn't have one its on electronic points.

[JOWETTJAVELIN]

It would seem increasingly likely that the electric ignition is to blame...

[bmcecosse]

A complete spare dizzy is handy when this sort of thing happens...........

[eth]

Well I feel a little silly admitting this but the fault was simple and now so obvious (Hindsight and all that jazz).
I wanted to put my original carb back on but before doing so I gave it meticulous inspection strip and clean. In doing so I found the choke tube was stopping just less than a mm short of home. A bit more attention was paid to this area when cleaning, it still wasn't perfect so I gave up on perfection and fitted a spare throttle return spring. Stick now you swine!

Thanks all

Awaiting itys

[liammonty]

Woohoo! So my optimism wasn't misplaced then- only my idea of what the problem was! Well done for getting to the bottom of it, and enjoy the car!

[bmcecosse]

You said you had the problem with two different carbs - so a sticking choke on one of them is hardly the answer.... But as long as it runs - good luck !

[eth]

Believe me liam I will be enjoying moggs to the max! One day on public transport is enough to make anyone appreciate even a rubbish car on a whole new level and we're rolling in some of the best

Besides I can't complain I've done 6000mi in 6 months of ownership and this is the first time she hasn't been able to get me around. Thinking on it statistically this is the most reliable car I have ever owned!

[oldgranda]

Hi I had a similar problem with my MG Midget it turned out that the air breather connection at the manifold was loose simply jagged it up a little no problem since! Good luck.

[eth]

FURTHER FINDINGS: the throttle slide was picking up a bit of resistance at its lowest position. With a bit of fiddling I found this could be remedied by fitting only one screw to the dash pot cover, even the slightest pressure on the second screw caused the slide to become sticky. Shes now nicely tuned and happy again and so am I

SUMMARY: sticky choke piston and throttle slide.

Lame I know but its a big learning curve for me keeping this old girl on the road especially when the car is nearly three times my age

[bmcecosse]

It's NOT a 'throttle slide' - it is simply a method of adjusting the mixture according to the air flow - your 'one loose screw' is NOT the way to run the carb. Something is wrong - try rotating the bell 180 degrees -and fitting both screws firmly. When the 'choke' is pulled - does the piston rise and fall easily? Is it only sticky when the 'choke' is fully home? If so - there is a problem with the jet assembly - early H2 carb it needs centering (see the Manual), later HS2 carb the jet may be damaged and needing renewed. It's also entirely possible that the needle is damaged/bent - or is the stickiness there even when the 'choke' is pulled - then the problem will be in the piston/bell pairing - they are not interchangeable with other parts, and should be kept as a pair. Light cleaning with WD40 and Brasso in extremis is permitted. But the piston must slide easily in the bell - and of course there must be a light spring in place on top of the piston.

[eth]

Do you ever tire of being right? The jet needed centring.

When centring should the piston still hit the bridge with the jet fully home? On mine the jet always lifted the piston 10thou even with the lock nut loosened. Is this to allow for more accurate centring or that the needle or jet are damaged?

With the adjusting nut fitted and adjusted the piston now falls freely with a satisfying clunk and all screws are present and tight does this meet ones approval?

[bmcecosse]

Nice clunk is correct. Sorted! If you don't want me to answer your queries in future - just let me know...