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MG MGB Technical - Visible smoke

Thanks for the replies on my other threads about emissions. Some mentioned ther MGs were only tested for visible smoke. Now I looked through my previous MOTs and there are no emission checks. But this station did one.
Looking at the age qualifier, 75 and later need a test, mine is a 76. But the engine and carbs are out of a 74 can't see how this would make much difference but would it?
c cummins

This MOT info site http://www.motuk.co.uk/manual_730.htm does say that the test applied should be for whichever is older, car or engine, so yours should be tested as a 74.

It certainly can make a difference, even though it applied much more to the US the factory were chasing tightening emissions standards all the time. Whilst home market cars got HIFs for 1974 they had new heads and different spec carbs and needles for 75, the emissions limit checks started on cars registered on or after 1st August 75, before that it is 'visible smoke only'.

Have you registered the change of engine with the DVLA? "The onus is on the vehicle presenter to prove engine age". The only way I can see of doing this is to show the testing station the relevant section from Clausagers 'Original MGB' that gives the dates for each engine number prefix.
Paul Hunt

That's interesting, especially about the HIFs because I replaced mine with Hs4s because of overflow problems. With cars that are this age, proving things like this must be difficult.
Having said that thanks to advice from this Forum it flew through this morning, and it feels like it's going better than ever.
c cummins

I had repeated overflow problems on one HIF as well despite two changes of float valve. It was only then I discovered the float contained some fuel but was very difficult to see! Since replacing that they have been fine.
Paul Hunt

It was random on mine in spite of changing floats and needle valves, including grose jets. In the end I changed because it was an hour and a half to fix it on HIFs and minutes with HS4s. Having said that it as only happened once since.
As I've not got a lead free head, I suspected the LRP was causing the problem.
c cummins

"an hour and a half to fix it on HIFs and minutes with HS4s"

Absolutely! Which is why when people ask whether they should use HSs or HIFs when converting from the single Zenith I always say "HSs!". HIFs are a pain, for that and other 'features'.
Paul Hunt

This thread was discussed between 22/07/2009 and 24/07/2009

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