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MG Car Repair/74 MG carb follow up


hi Barrie - thx for the link on HIF, however my MGB was a conversion  to HS4 type SU's. on the HS4's is it possible that the jet needle is adjusted wrongly allowing gas to flow? Gas is immediately pooling and pouring from the intake ( but the bowls are not flooded, nor is gas flowing into the vapour hoses.)

Hi Paul.  No, the jet needle is only a metering device.  It should never touch the jet, not even when the engine is switched off.  The fuel level should be below the top of the jet, so fuel only flows when the engine sucks it out of the jet.  

If fuel is pouring from the inlets you have a real problem.  

Have you done ANYTHING else that might explain your symptoms?  For example, I recently diagnosed a problem where the timing chain had been replaced.  The camshaft was timed incorrectly, so instead of sucking fuel, the engine was blowing fuel out of the carburetters.  

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Barrie Jones


MG Sports Cars from 1949 to 1980 - Including MGB, MGBGT V8, TF1500, TF, TD and modern Midgets. I also specialise in SU carburettors, Lucas wiring, suspension, steering & brakes.


I have owned my 1955 TF1500 since 1966. Technical specialist for the TD and TF with the MG Car Club T Register. Also owned 20 MGBs and currently own an MGBGT V8. Written 3 books on MGs and produced a DVD on how to strip and rebuild the TD/TF gearbox.

MG Car Club.

Barrie's Notes on the 1953-55 MG TF (author). /=====/ Barrie's Notes on the MGB (author). /=====/ Barrie's Notes on the MGB GT V8 (author). /=====/ The Essential Buyer's Guide to the MG TD, TF and TF1500. (author)

M Phil, C Eng, BSc (Eng).

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