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MG MGB Technical - PLEASE!!! Help get BGT started

recently bought a '68 BGT. It has not been started in about three years. The work I have done so far is as follows.
Rebuilt carbs (HS4's) and mounted back on engine. Installed new throttle cables and fuel lines. Put in new fuel and got pump working. Floats get fuel just fine, and jets are clear.
All that really doesn't matter because I'm not getting a spark. Was just showing that I got the fuel side working.
I got a new battery and went to start it. The engine turns over slowly, has if the battery was almost dead. So I took out the plugs and cranked the engine to get some oil up in it. It did crank a little faster but still not like my dad's MGA cranks. I took the battery out and put it in my Accord to test it and it starts it without a problem. So back into the MG it goes.
Since I new it had fuel (carbs seemed to be working just fine, plus I put a few drops of fuel into the cylinders), I checked to see if it had a spark...NONE :(
With the ignition on, I checked to see if any voltage was getting to the coil, and got about 10 volts at the leads to the coil. Next I checked the main lead coming out of the coil that goes to the distributor and got about 12 volts. This seemed odd because coils are supposed to make lots of volts to generate the spark. After talking to my dad I found that you can't test a coil that way due to some reason that went over my head (I'm just a pilot not an electrical engineer)
Next I checked to see if anything was getting to the ends of the ignition leads and got nothing. Not knowing if this was a viable test I went back to the trusty Accord. I got 12 volts at the coil and a pulsing 12 volts at the ignition lead ends as I was expecting.
This leads me to believe that there is something wrong with the distributor, but my dad thinks that the starter is taking all the power and not leaving enough for the ignition system to make a spark.
This not getting the car to start is making me frustrated and sad, and I even thought about selling her and buying one that is running. Please help me stop this sinful thought and get her running again!!!

Sorry for the novel.
-Steve
Steven J. Korotky

Steven: This BBS is a font of knowledge. Rather than try to duplicate what has been described by others much better, I suggest you study this:http://www.mgcars.org.uk/electrical/start_fault.html, and systematically follow the diagnostic procedures.
Andrew Blackley

Sorry, that link didnt seem to work, try this:http://www.mgcars.org.uk/electrical/starter.html
Andrew Blackley

Andrew of course the ansewer is somewhere else but what fun is that?
Steven, take the distributor cap off, tap the key until the distributor shaft moves to close the points. With the key on,and the car in neutral, stick a clean spark plug with a wide gap 40-50 ths. in the distriputor end of the secondary wire coming from the coil, ground the plug to the cylinder head. With a little screwdriver open and close the points a little [10-15 ths] while watching the gap end of the spark plug you should see a blue spark if not try scraping the points back and forth while they are closed while watching for a spark, if you get a spark now, clean/replace the points if not write back and I'm sure we can get it running one step at a time RIC
R E L Lloyd

If you haven't already, it would be a good idea to remove all of the spark plugs and squirt a couple of shots of oil into the cylinders. This will help since the engine hasn't been started in three years.

Also recharge the battery and check the cables, terminals, and ends. I ran a piece of welding cable directly from the negative post to the block on mine. It may not be necessary, but makes good connection and eliminates dependence on the block-to-frame ground cable.

Once you get it to crank, it wouldn't hurt to crank it a little with the coil wire grounded. You should see an oil pressure reading on the gauge. That'll pre-lube it a little and put some oil on the bearings before the initial start up.

Have you checked the plug wires with an ohmmeter?

Good luck.
Glenn

Try swapping the distributor rotor of a new one.

Some Lucas rotors develope an internal short
and grounds the sparking current through the
distributor spindle shaft. This is not visible
nor can it be easily tested with a multitester.

This one happened to me and left me scratching
my head on the side of the road for hours.

Pep Boys carry distributor cap & rotor for the MGB
made by Borg-Warner.
Daniel Wong

With 12v on the coil +ve and the points open you *will* see the same 12v on the coil -ve and the HT connection. This is because when the HT lead is connected to the distributor cap there is an air-gap at the rotor i.e. to low voltage DC it is open circuit, and the other end of the HT winding is connected internally to the coil -ve. You will only get the very high HT voltage at the instant the points open, and it wouldn't register on a typical multi-meter anyway, you would need a scope or similar to see it.

Turn the engine, plugs out, by hand and monitor the coil +ve with a meter connected to ground. On a CB car you should see a constant 12v, maybe a small drop and rise as the points close and open (an RB is different). No 12v on the coil +ve, or seeing it drop more than a few tenths of a volt when the points are closed, indicates a disconnection or bad connection in the white back to the fusebox or ignition switch. Still turning the engine monitor the voltage on the coil -ve with the meter, and it should switch between 12v and ground as the points open and close. As the points open (cap off) you should see a small spark. If you see all that you should be getting a spark if you have the HT lead connected to a plug laying on the block. If not I'd change the coil. A permanent 12v on the coil -ve means a disconnection towards the points. A permanent ground on the coil -ve indicates the points are closed up or shorted out, this can be from a faulty capacitor or incorrect assembly of the condenser wire, coil wire and points.
Paul Hunt

Thanks for all your help guys!!!

I got her to run today, even if it was only for about 10 seconds on starter fluid (the fuel pump wasn't happy today and therefore couldn't refill the bowls)

I think the problem was that the distributor points had a 0.050" gap rather then the 0.014 - 0.016 it should be.

-Steve
Steven J. Korotky

Steve, if you suspect foreign matter in the fuel line and if you have an air compressor you may want to disconnect the fuel line at the pump (filter side) and filter (pump side) and blow the line out at about 20psi. If you do, blow from front to rear.

While set up for that, it'd be a good idea to also disconnect and blow out the fuel bowl overflow lines.

I'm not too smooth at setting points with a feeler gauge, so I always use a dwell meter to verify things.

Glad you made progress.

Glenn

This thread was discussed between 06/09/2003 and 08/09/2003

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