QuestionQUESTION: I am currently re-building a pair of SU's for an MGB. ON reinstalling the cold start spindle and cold start body I need to know how to align them with regard to each other and of course the carb body. None of the manuals to hand mention this important aspect. Yes, next time I'll mark the components before removing them! All guidance gratefully received.
ANSWER: Hi Anthony.
I assume that you have a UK specification car with twin HIF4s and no special auto-enrichment device?
The HIF4 carb has a separate cold start spindle, so it does not rely on the earlier method of enrichment (physically dropping the main jet).
If you look carefully at the cold start spindle, you will see that it has a groove in it that only fully lines up with a drilling in the main SU body when the choke is fully engaged. When the choke is not engaged, this drilling is closed off by the spindle, preventing the supply of additional fuel. That should give you a clue as to which way round it goes.
There is a good book covering your MGB, and it has a section on the HIF carburettors. It is called the "MGB Repair Operation Manual", and was published by British Leyland under part number AKM 4070. Copies should be available from the MG Owners Club or Moss. Another good book is the "MGB Workshop Manual" published by Unipart under part number GWM 9350.Looking at page 46 there is an exploded diagram of the cold start enrichment device which clearly shows how it fits together. I could photograph that page and send it to you if you would like that.
Get back to me if you need more help.
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QUESTION: Hi Barrie. Thank for the input. The carbs are FZX1001. The spindle carries two fairly wide grooves which are for the seals. Then there is a small hole drilled right through the spindle with the sides grooved out to regulate the amount of extra fuel to flow I assume. either of these hole align with the small hole drilled through the cold start body which in turn aligns with the drilling in the carb body. The cold start body has a circular ring where it fits to the carb body with a cut out which must align with the carb body. Unfortunately I cannot see any marking on the carb body to help align the cut out with. If you couls forward the relevant page It may help.
regards
Anthony
Answer
HIF choke diagram
Hi Anthony
Looking at the side of the carb, the cutout in the flange of the outer part goes at about 11 O'clock, which places the hole in the outer at about 4 O'clock. The hole in the inner goes at about 5 O'clock when shut and at 4 O'clock when fully open. Don't forget the paper gasket which also has a small cut-out in it.
Not sure how to attach a photo but I shall try.
