77 MGB cutting out and backfiring

[waltmcc]

Had car 9 years but running poorly. Replaced points, cap, rotor and condensor. Now runs much better except engine cuts out, tach to zero, and occasional loud backfire. Once would not start at all - no spark at plugs, so restored original condensor and started OK, but now same problems again. Considering replacing coil. Help appreciated.

[glennet]

I would check the connectors of the high tension wires at the coil.
They are a spade type connector - and the wires can be loose or broken - but may not be visable because of the sheathing over the wire at the connector. Getting your hands and arms in positon to adjust the points - it's real easy to bump the coil wires. As a tip - next time you may want to just remove ditrbutor from car - and do your work on the bench - much easier - just remember to check the position of the rotor before removing the distributor. Good Luck ---

[Flash75]

How do the plugs look? You didn't say they were replaced. Lots of problems with condensers I would try another new condenser. Check the resistance of the plug and coil to distributor high tension wires, they should have around 5-6 k ohms resistance. Are you saying the car hasn't run well in 9 years? If that is the case you need to do a complete tune up to check the health of the engine.

Clifton

[waltmcc]

Thanks to Flash75 and Glennet. Since posting the problem, I discovered the high tension lead at the coil was not properly seated (self inflicted when replacing the dist cap), and car is now running better than for some time - still sluggish enough at low revs, but going well higher up. I'll replace the condensor again with the new one.

[Flash75]

If it's running OK now I wouldn't replace the condenser, sometimes new ones are bad. It would not be the reason your engine is sluggish.

Clifton

[Lyle Abel]

It sounds like you have the problem resolved, but will share my experience with you. Perhaps it will help someone in the future. For 20 years I have had a 79 MGB that has sailed through Cal smog tests. Recently I took the car for gas ( seldom driven ) and on the way I had serious back firing and the car did not want to run. I thought it was the hot water choke on my Zenith Stromber carb, so I removed it and reinstalled it..same problem.. I found that the choke body was loose from the Carb body ( 3 screws ). I tightened them and that solved most of the problem. Only problem now is that I can't get the car to SMOG. It is in the Jag dealers garage as I write this...Check for loose connections at those screw terminals, but do not overtighten them because they strip very easily...