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MG Midget and Sprite Technical - su carb adjustment and choke

after rebuilding my 1275 71 midget got feed up trying to adjust my old su carbs and I broke down and bought new carbs. but I am having a hard time adjusting them. I followed instructions I have on adjusting but I cannot seem to get it to run unless I have it choked. It is up to temp then I unchoke it and it dies. I finally got it to run somewhat having it very rich (20 or so turns on the nut under the carb). I started at 12 turns and when I lift the piston the engine stalls so I keep turning rich until I get it to stay steady on the piston lift. I hope my description is not to bad. This is really the same thing that was going on with my old carbs. I took my car to a mg mechanic when I had the old carbs on and he said I had them adjusted about as good as could be done. He recommended a rebuild so I just bought new ones.
Makes me wonder if there is a engine issue? I have electonic ignition and I have check the timing a valves and checked for vacume issues also.
Ken Bargeron

Ken,

Hesitate to say, as you've shelled out for new carbs, but are you sure this is a carburation problem?

I spent a week trying to setup the SUs on my frogeye before I found the problem lay in the electronic ignition. At one stage I was almost 20 flats down on the jet-nut as well but the engine still wouldn't run properly at under about 1,800rpm.

In the end it turned out to be a duff electronic ignition unit. See threads "Frogeye won't idle" and "Frogeye won't idle (2)".

dennis
D Stanfield

just to clear up....

what did you do to the engine at rebuild....hotter cam, bigger valves, over-sized pistons...ect. ect.

did you check for vacume leaks around the carbs and intake manifold.

As stated above....make sure your ignition is clean and up to par

is the Su pump working properly....good fuel flow

is the heat shield installed at the carbs

are the wire bullet connectors in good shape...(no rust, moisture) on the bullets and sleeves in the wiring of the ignition system...(and to the fuel pump and tach.)

Have you screwed blindly and hit an ignition wire....fire wall, fender wells, radio consel area, ect.....what about a pinched wire in the same vain as screwing blindly...(Yeah I find screwing blind effects my eye sight also...lol)

everything okay inside the dist.

have you tried running the car in a dark shop and looking for an electrical blue light show.

Are you still running a generator or have you done the one best thing ever for your car and upgraded to an alt.


prop
Prop

This thread was discussed on 23/07/2008

MG Midget and Sprite Technical index

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