No Power under load and backfiring out of carb

[Dumbledorbin]

Hello all.

Finally got my engine in my 1300 and its running. it seems fine once warmed up stationary. revs freely. but the second you try and drive there is no power and a bit of coughing and spluttering out of the carb and wants to cut out. anyone have any ideas?

P.S im a clueless 20 year old thats just trying his best to keep an old car on the road and i have no idea what im doing. learning as i go along. any help will be appreciated.

Thanks in advance

[AndyJ]

It sounds like a weak fuel air mixture and/or ignition timing issues. The weak mixture can be due to carb set up or air leaks into the manifold. You need an engine tune and to check the manifold for leaks. You should also be aware that an engine running with those symptoms can cause damage so I wouldn't delay it drive any distance just to be sure. The question then is whether you want to take it on yourself or if you'd rather get someone else to do it for you.
Andy.

[GTS290N]

Once it's running you could try pulling the choke out and see what happens - if it runs it could mean a weak mixture.
Do you have or can you borrow a strobe light to check the timing?

[tractor boy]

Sounds like condenser is breaking down to me . Tractor boy

[Mahesh]

Check if anything has come loose, fuel pipes, breather hose,
(an old fuel pipe may have split), also check carb dash pot oil level and that the piston assy inside the dash pot is not stuck.

[Toledo Man]

You will need to start with the ignition (congrats for getting it running). Make sure you're getting a healthy spark. There are some poor quality ignition parts out there. Have the ignition timing set to the book figures and have it running on super unleaded (worth the extra it costs). Electronic ignition is worth fitting. Once you know the ignition is 100% you can then move on to the carbs. The first thing you need to do it to pull out the spark plugs and the colour of the electrodes will give you an idea of what the mixture is like. If the mixture is fine then it should be a light brown colour. If the idle is uneven then you probably have air leak somewhere.

[MIG Wielder]

Its probably worth checking the valve clearances as well since its a 1300 OHV engine. That would also reveal any sticky valves as well particularly if the engine hasn't been run for a while. I find the OHV clearances on the MGB do move around a bit.
Tony.

[Dumbledorbin]

I am going to check cam timing today. it was an old engine lying around that nobody knew the history of. bores seemed okay no scoring etc etc. all work done on the vehicle will be completed by myself. it was a struggle fitting the engine myself with no engine crane but i somehow managed it. someone mentioned electronic ignition ive got one sat there i tried fitting but would not fire up at all with that fitted so whacked the points back in. and it starts first turn of the key. when pulling the choke out it seems to run a little bit better than with the choke pushed in but only marginally. less coughing and spluttering out of the carb.

[GTS290N]

Get it running reliably on points before fitting electronic ignition. Ignore electronic ignition for now.

[Toledo Man]

I second that. When I fitted electronic ignition, I made sure it was running fine on points first.

[xvivalve]

This could be any manner of things from simple matters like crossed HT leads, or in a worse case scenario that I suffered on my Interceptor, that of a worn cam lobe on an exhaust valve. You need to start from first principles and systematically check everything is correct: plugs, leads, gaps, points, static timing, mixture etc etc

[Magenta Auto Sprint]

I had similar problem on my 1385 min many years ago, points gap was wrong, almost non existant due to heel on the points wearing excessivley and another time it was a crack in the distributor cap which caused tracking.

My MoT man also told me that he had spent hours trying to get a mini running well after the owner had been playing with it and fitting new parts, firstly he found a bent SU needle and the new condensor (as mentioned previoulsy) was defective.

Hope it is soon sorted.

Malcolm

[SprintMWU773V]

There's far too many scenarios here. Keep it simple and start with the basics first and if you've done any work in the area look at those bits first. If I were a betting man I'd personally go fuel or HT leads as to me the big clue is it doesn't work under load. I've had both on cars before once was fuel related due to an air leak and the other was a set of HT leads breaking down but only when it got hot.

More than likely it's fuel for you. You can tell a weak mixture by the exhaust smell as much as it being too rich. Mixture may be weak for all manner of reasons from inlet air leaks, sticky floats, crud in the fuel line to name but a few.

[Dumbledorbin]

seems it was ignition timing. thanks all for you suggestions. oil light wont go off now. i dont think it has an oil pressure relief valve would this cause this. if so does anyone have a part number so i can get one ordered?

[Triumph1300]

DON@T RUN IT< I told you when you took the block it didn't have a pressure releif valve in it.

Take the PRV out of your old block, it's behind the big hex nut that screws into the block below the distributor.

It's basically a spring, and rod affair.