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MG Midget and Sprite Technical - Non starter.


Back again gents.
New exhaust manifold fitted. Fuel there. Refuses to fire up. New electronic ign also just fitted. Had it running rough before new manifold. HIF44 on. Removed plug and cranked. Spark appears weak ?
Could this be an earth problem. Just got the std.body to belhousing lead - all clean.
Anybody had this ?
G Bewick

If it cranks readily the earth is probably OK. Did you take anything else apart to fit the manifold, if so start by checking that.

Otherwise go back to basics and check static timing, points gap if you still have points, plug lead order. Get a new set of spark plugs, connect and line them somewhere (I put them on top of the alternator to get an earth) and crank again, do you see a nice regular firing pattern? If not something is up.

At this point I checked compression on mine and found it was down in middle two cylinders, I hope that's not your problem. I will be lapping valves in at the weekend.


AdrianR

The thing that stands out to me is the fitting of a new electronic ignition, when was this fitted, when you had it running rough, after new manifold or both and did the car run well before it was fitted?

As Adrian's put checking or rechecking the basics is always good, below is what I usually put, yours would be igniter instead of points obviously -

• set up tappets, CB points, plugs, timing and mixture in that order, if you have to adjust any item in that chain then you’ll also need to check, and adjust if required, all the items that follow it in the chain
Nigel Atkins

If you have just fitted one of the little elec' ignition modules, do you need to reset the timing?

I can't remember for sure, but I thought that when installed they were typically about 20 degs or so out (just a function of the way the parts fit and are aligned inside the dizzy). So you need to reset the static timing.

Or maybe I dreamt that?

Malc.
Malcolm Le Chevalier

Echoing Malc, I also had to reset my timing when I added a pertronix module several years ago. Once that was done, it hasn't skipped a beat in a very long time.

-:G:-
Gryf Ketcherside

Leak at new exhaust manifold?
GN Rowles

What a half wit!
Had no. 2 and no. 3 leads wrong way. This weird side exit dizzy cap to blame. Fired up and runs sweet.

Thanks gents.
G Bewick

Not to worry at least you got it sorted, as usual checking and rechecking the basics is always good idea.

A mate has decades of car mechanics experience yet he still done the same as you once on my car (mind you I bolted one of his suspension arms above instead of below once too).

Would this have helped -


Nigel Atkins

Gary,
that is such a universal mistake to make the embarrasment is on the rest of us on the BBS not to mention it as a likely cause of the problem right from the very start!
Or should that be from the failure to start!
GuyW

Gents - problem resolved at the end of the day. Maybe sometimes we look too hard at concerns and should just stand back and have a damm good head scratch !

While i'm here - King Pin play.
If i replace KP and lower fulcrum with new - will i have to bother with this reamer thing as i have no idea WTF one of them is ?
G Bewick

Gary,
The reamer is needed to open out newly installed bushes in the swivel hub to the correct clearance for a king pin. If your swivel hub bushes are worn you have two options. One is to remove the old bushes, replace with new and then ream. The second is to buy a reconditioned swivel hub ready prepared to match a king pin, in which case you don't need a reamer.

But before that, you do need to be sure that these parts need replacing. And at the same time do check the other potential wear areas discussed. There is little point in repacing one part if others are also seriously worn.

Check again the wear at the top of the swivel hub, below that large upper trunnion bolt in your photo. When you felt for movement there, was it slack side to side, or vertically on the pin? (rotational movement is OK - that is what it is supposed to do!!)
You need to do this checking with the car jacked up and supported on the chassis, not on the lower wishbone.

If the slack is side to side, then the bushes are worn. But if it is vertical then first check that the nut at the top of the kingpin is good and tight. If it is, and there is still vertical movement then it may be possible to adjust this out by removing some shims from the top of the king pin.

Also, bear in mind that a little slack is normal and acceptable on older cars like these, though some MOT garages may pick up on it. It is worth making sure that the kingpins are properly greased before taking it for an MOT anyway.

The other common areas for wear are wheel bearings and the fulcrum pin / bottom wishbone bushes, so do check those too.
GuyW

This thread was discussed between 18/10/2017 and 22/10/2017

MG Midget and Sprite Technical index

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