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Do I need carburetor work?

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gfaubus

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My 69 MGB runs fine (after about 10 minutes warm-up)on the open road, but after 30 miles or so of cruising and re-entering the city it gets all finicky spits, sputters, backfires. Do I need to adjust/rebuild the carbs? /ubbthreads/images/graemlins/confused.gif
 
I'd be lookin' at the choke, and the jet mixture settings. It ~sounds~ like it's runnin' rich.
 
90% of all carb problems are electrical. Check your ignition system. Are the points pitted? Is the coil too hot to touch? How do the plugs look? Try a new rotor cap and condenser. Both are of very low quality these days and can cause running problems.
 
Could also be a float problem. If there's a leaky one and it is half sunk, it'd allow fuel past the needle in larger quantities... Just ask BoneIdle... he had it happen a week or so ago.
 
Amen to that, Doc! In fact it was passing substantial quantities of fuel past the carbs! Initially, it would run fine while choked and get a little odd when at normal temp, but at the last there, it would only run while fully choked.
Now to drain the tranny and OD...wish me luck everyone!
 
You might need to twiddle the carbs, but as Steve says, most carb problems aren't (carb problems, that is). Check ALL the other stuff first -- valve adjustment, ignition system condition, points gap, timing (in that order) -- and verify that it's all correct. Only then should you touch the carbs.

HTH!
 
yep, I agree with Doc. Oh yea, I mostly agree with Doc. But darn he is mostly correct. Got to be choke I should think.
 
OK, thanks. I think I'll start with the points and valve timing stuff, I'm a lot more familiar with those things anyway. Also, sometimes after a longer drive it tends to 'run-on' a bit after shut down and a couple of times I've had a shotgun loud backfire after shutting the engine down.
 
Over-rich, and a timing problem... and do you run the highest octane fuel you can find? You should.
 
Sounds like it could be a timing problem to me too: if you have too much advance, it will cause overheating and that can cause the run-on problem as well.
 
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