MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Rough Running Cured -TWICE

Regular readers may remember I was having real problems with the TF running rough, spitting through the carbs and backfiring. After literally weeks of working on the car, a partial engine strip down and replacement of all the serviceable ignition parts I changed one of the carb jet tubes for one I had left over from a rebuild of my 1932 MG. Immediately the engine ran like an Omega watch. I have now replaced jet tubes an needles and today went to a MG Car Show about 50 miles away and the MG ran smoother than my 2016 Mercedes! But, very interestingly, a friend who lives close by was having similar problems with his rebuilt TD engine. After checking timing, mixture, plugs, distributor cap etc. we tried the jet tube from my old pre war MG in one of the carbs. Again a huge improvement! New jet tubes and needles are now fitted and the engine now runs superbly. I have been messing with SUs for 40 years and must admit I have never bothered to replace jet tubes or needles but you learn something every day.

Jan T
J Targosz

Very interesting Jan. What was wrong with the jet tube that you replaced. General wear on the bore or something else?
Dave H
Dave Hill

I am the friend that Jan refers to in his post,and can confirm what he says. My engine was running a bit rough and was reluctant to pick up from tickover. I fitted new jets and needles and now it runs without any hesitancy. I am now waiting for a break in the weather to do a road test.!
So, what was wrong with the jets and needles? Impossible to say, they looked exactly the same as the new ones and the needles even measured the same with a micrometer.
Obviously there must have been wear in the jet bore. I accompanied Jan to the car show today and his TF is running beautifully.
IW Martin

Hi Dave,

The only comonality between Bill's car and mine, apart from the misfire and spitting, is both cars have recently undergone a restoration. The fuel tanks have been empty for some time and despite filters behind the float banjos the chambers did have silt and water in them. I wonder if some of this has entered the jet tubes and scored them? I know the tolerances are very fine. My advice is if anyone is having problems with backfiring and spitting don't ignore the jets and needles.

Jan T
J Targosz

20/25 years ago somebody in the UK was re-manufacturing jets.
His method was to solder a thin brass washer to the head and re-drilled to 090". as you can imagine they wrecked the atomisation and wore out quickly.
They appeared at autojumbles and caused chaos.
Ray TF 2884
Ray Lee

Hi

Just rebuilt my carbs using the Burlen rebuild kit which is very comprehesive with bushes and jets. The difference is quite remarkable both in starting and running, so I can echo Jan's comments.

Barry
B Bridgens

This thread was discussed between 25/09/2016 and 26/09/2016

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now