QuestionQUESTION: Kind Sir, I have a 79 mgb. recient purchase. Was running rough when I bought it. Did a full tune up, rotor, cap, wires, plugs, adjusted valves. I don't have any fire on #1 or #2 plugs. I have swaped the dist. and coil from a 1980 mgb that runs fine. and got the same results, I installed a new electronic dist. and still do not have fire on #1 or #2. I have maintained my cars for about 45 years and never have I had a problem like this before. Please help. Thank you. Walter
ANSWER: Hi Walter
When you say there is no fire on #1 and #2, how did you test this?
With heavily insulated pliers, hold #1 plug lead (wire) about 1mm away from the metal of the cylinder head. Can you see a spark? Do the same with #2. My guess is that you will see a spark, in which case you do not have an ignition problem at all.
I think your problem is more likely to be a burnt out head gasket between cylinders #1 and #2. To check my theory, I would do a compression test on all 4 cylinders. The actual readings do not matter, so long as they are all within 10 psi of each other.
If only one cylinder is down on pressure, it is a burnt out exhaust valve. These heads were slightly hardened using an induction process, but they really need hardened valve inserts for all 4 exhaust valves.
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QUESTION: Hi Barrie,
Thanks for the quick reply. I have tried all of the usual test. There is no spark on the plugs or plug wires. I removed the dist. turned the switch on and rotated the dist. shaft and could not hear a spark in the dist. on # 1 and # 2 terminals as the rotor passed the post in the cap. It is an electrical problem somewhere?? I just don't understand why the dist. is not providing fire on the 2 plug wires? I have tryed different plug wires all ohmed out good. I even run a hot wire to the coil to by pass the ignition switch and ballist reistor same results. I have been working on this problem for several weeks now. It is driving me nuts. Thanks for your help. Walter
ANSWER: My immediate reaction is a faulty distributor cap. Also the plug leads (wires) often give problems, and should be replaced. If you have points, they could be too tight, plus a worn distributor bearing could prevent a spark on one side of the distributor. Seems strange that it is happening on 2 cylinders. Trying a good dizzy from another car eliminates all the above, so it must be elsewhere.
Are you absolutely sure it is electrical? Cylinders #1 and #2 share the front carburetter. I would check that out next.
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QUESTION: Hi Barrie,
Yes! I am positive it is an electrical problem. No spark through the plug wires. I just don't understand it. If 3and 4 have fire, why doesn't #1 and #2. I also thought maybe the dist. shaft had play, but it is ok. I have tryed different rotors and different caps. I even tryed a 6 volt coil. I am out of trouble shooting ideas. I know that this is an unusual and difficult problem for you to troubleshoot over the internet. Maybe a little gas and a match will solve the problem? LOL. I do sincerely appreciate your help. Thanks, Walter
AnswerWould you mind telling me exactly how you are testing the wires for fire? It doesn't make sense. I am missing something here.
When you fitted the dizzy from the 1980 B did you also transfer the rotor arm, dizzy cap and the plug leads? I want you to replace EVERYTHING, right down to the spark plugs.
... and keep away from those matches.
