1970 MGB coil gone bad?

SPELBYNDER

MEMBER
1970 MG MGB

Engine Performance problem
1970 MGB 4 cyl Two Wheel Drive Manual

I inherited the car from my dad several months ago with no info regarding it. Since I've had it, it has always had low acceleration and power and took several minutes to get to its top speed of about 50 mph, pedal to the metal (higher if going downhill!).
It would be a little difficult to start in the morning (I used starter in the single carb--the dual carbs had been replaced before I got it), but it would run much better when cold, and the performance would decrease the warmer the engine got.
A few days ago, it started slowing down (even more than usual) and I was only able to reach a top speed of 35 mph. I quit driving it and started researching what might be the problem.
I am an amateur mechanic and am able to do most maintenance and simple parts replacements myself but I'm not so good at diagnosing problems unless they're really obvious. Any help would be appreciated.

1 Reply

HMAC300

MECHANIC
48,601 POSTS

If this has a single carb then it's like a 75 up b. If it has a catalytic converter i'd check for a plugged exaust. A vacuum guage with a low vacuum reading will give you a tipoff. Of course i'd check the points first and the other tune up stuff- plugs, etc. Disconnect the coil wire and short it to the block while you turn the engine over, if you are getting a spark it should be ok. It also depends what ignition system you have as well. But I think i'd go for the exaust problem. YOu can always put a header or different carb system on it if that's the problem. It won't be cheap if you buy new but yo might find an older mgb that is being scrapped with what you need.