QuestionQUESTION: When it started it would run great for a 10 minute drive or so then loose power and literally not be able to make it up a small hill. a friend suggested it might be the fuel pump so my local Napa guy said he had one to fit. It is not like the original but I put it on and it seemed allot better but eventually ( 30 minutes) the same thing happened. So I thought is might be the points...I pulled the distributor, marked the rotor direction position of the distributor. My MGB has a distributor with points. Now wont start at all...no spark at the plug when I pulled it, put the wire back on and cranked the engine. Would timing cause no spark? How do I check the coil? What else should i look for? When I changed the points the new ones were slightly different with a u shaped insulator. I tried the condenser wire and internal wire on the points spring and also above the u shaped insulator and no difference. Really puzzled. Thanks for reading all this, Bob
ANSWER: Hi Bob,
It sounds like you put the points in wrong. The points came with an insulator in two halves connected by a small string of plastic. The way you were suppose to install the points is to place the points in place and put the screw in just snug, then put half of the insulator on the threaded stud with the small part up. Then put the spring on and the condenser wire and pig tail wire both against the spring and then put the second half of the insulator INTO the two wire ends and into the spring so that the spring nor the two wire ends make contact with the threaded stud. Then you can install the washer and nut. The objective is to have the condenser wire and the pig tail wire ends make contact with the spring but NONE must make contact with the threaded stud they are mounted on.
To test it, set the points gap on a point of the cam at .015" and then turn on the ignition and check the coil wire with a test light. The test light must light up. Then turn the engine until the points are closed and check it again and this time the light must not light up.
No! timing can not make the ignition not fire, it can only make it fire at the wrong time.
As for the original problem, it sounds like either a partially stopped up exhaust system or a fuel supply problem.
let me know when you get ignition again and I will go over the test procedures for fuel supply or a stopped up exhaust system.
Howard
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QUESTION: Thanks Howard the points did the trick.....for the fuel and exhaust I would appreciate the answer as well. A couple of years ago chipmunks filled my muffler with acorns ( we live in the woods) and it took allot to figure it out so if there is an easy test that would be great!Bob
AnswerAn easy test for a stopped up exhaust is first the symptoms are that it may run at idle or low RPM and low loads but as soon as high RPM or high loads are applied it tends to just level off with no power. Then a preliminary test is to check manifold vacuum as the RPM is slowly advanced. It is normal for vacuum to go down as RPM and load go up but even under full throttle, full load the vacuum should not go below 5 in hg.
All that only points toward a partially stopped up exhaust. A final 100% test is to either drop the exhaust from the headers or drill a hole in the pipe close to the front just a little smaller than the diameter of a piece of brake line. Then cut a short piece of brake line about an inch or two long and drive it into the drilled hole and put a low pressure gauge on the piece of line. (most vacuum gauges have a fuel pressure section that can be used) Then run the RPM up until it goes flat and read the gauge. I have tested many different British cars and found that none could stand more than 1.5 PSI back pressure. At the time the engine goes flat or loosed power the gauge will go up very high if the exhaust is stopped up at all.
Howard
