Morris Minor Owners Club

Hi I need some HELP !!!!!!!!!!!!!!

Recently got 1962 traveller (very cheap) great overall condition but it doesn't run well.... It starts an ticks over great, fires first time every time BUT as soon as you push the throttle more that just a little the engine cuts out completely - if you push the throttle a very little it will rev up well.

I've stripped and cleaned carb, adjusted the needle centering so the needle drops great, the mixture seems fine as if you push the bottom lever to raise the pin the revs don't change.

It sounds like a no fuel mixture when the throttle flap opens, just enough for the tickover?? The float level is fine, needle doesn't appear to be bent and no dirt/water in the fuel.

Also don't know if its relevent but there is no vacuum advance unit on the distributer?? as shown in the haynes manual?? I've blocked the hose that would go to the advance unit as that was open. I've adjusted the timing a couple of degrees A + R whilst running and it didn't help so it's back to where it was and I don't think thats the problem.

Any ideas?? Anyone in the worcester area good with carbs??

Really appreciate any suggestions

Thanks
Nugget

It sounds like a weak mixture, but could be a few other things.

If you have access to a Gunson Colortune, you can check to see what the combustion chamber mixture is like under idle and quick throttle. It's a cheapish tool to buy, and great for setting up carbs or finding faults in the fuel or ignition system

You need to check.

Mixture at various throttle settings (Colortune)
Fuel delivery from the fuel pump (Per manual)
Float level in the float chamber
Spark intensity/Plug condition
Dizzy Condensor
ignition coil

Plus a common carb needle problem. Make sure the shoulder of the needle is flush with the bottom of the carb piston. If the needle isn't seated correctly, the mixture will be miles out.

As the car is new to you, I would start with a full service and engine diagnostics. Points/plugs, oil and filter change, clean check crankcase ventilation system, air cleaner. Do a compression test.

Re the Dizzy, older units did not have a vacuum advance unit, but if your dizzy has the fittings for one, it should be fitted, but the lack of one won't cause the problems you are having, it only advances the igntion a couple of degrees under no load (over-run mainly)

You will also need to check the assembly of the carb jet and choke linkages.

have you got the wright oil in the dashpot on the carb.i had too thick oil in mine.it would tick over but would not rev.you need an oil of 20 rating,3in 1 is fine.also check the filter in the fuel pump this might be full of rubbish,mine was blocked,cleaned out with petrol runs like a watch now,only a five minute job,will save you a lot of grief

The vacuum advance would not cause your problems but,as a matter of interest, it advances the ignition ONLY under no load conditions, i.e. when the engine is not under any strain. Since you seem to have done the usual checks re the carb piston and needle etc I would suggest that you remove the jet assembly and check that there is not a partial blockage which prevents the normal flow of fuel from the bottom of the float chamber to the jet. In other words there is enough to give a great tickover but not enough to allow anything more. I have had this twice on an SU equiped car and each time it was a tiny particle which did the damage.

Colour tune is a waste of time and money - the lift pin will tell all on an SU car. But i wonder about your phrase - 'pushing the bottom lever to lift the pin' - are you moving the choke ? The lift pin is just that - a little pin at the side of the carb that you lift with a finger - and in turn it lifts the piston inside the carb. Check this is what you have/are doing. And also - put some engine oil in the dashpot. The dizzy - MUST have a vacuum advance unit - all A series Minors had these - important for engine pick-up and for economy - and obviously it used to have one if the vac line was there! However - I don't think it's anything to do with this problem, which just sounds like a very weak mixture. Richen it up until it picks up ok - then try the lift pin test. Could also be taht the ignition timing is miles out - try advancing/retarding it to get the fastest/smoothest idle - then road test to listen for any 'pinking' - if there, retard slightly until pinking disappears!