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MG MGB Technical - boosted brakes


I would like to covert the braking system from my 75 MGB to the US spec boosted master cilinder.

Aditional to the master cilinder, I know that I need the pedal box and pedals, and I have to cut a bigger hole in the panel where the pedal box is mounted.

But...since my car is equiped with dual SU carbs, I'm not sure that there is enough space between carb/aircleaner (K&N) and servo/mastercilinder.

Can anyone clear this question?



Hi Gil,

air cleaners and emulsion blocks have to be modyfied.
You can have the emulsion blocks machined and shorter studs set to the manifold. Take care that there is still a gap to the heatshield.
Air cleaners have to be changed to the conical offset type. I took the K&N ones, but there are also other brands on the market.
I converted my 1975 California B this way and it worked, although space is very tight between the servo and the rear air cleaner.
Do not try to run the carbs without a heat shield, HIF carbs are wery sensible to fuel bowl temperature and change mixture automatically, HS carbs can suffer from air locks without protection.

Good luck


Gil - I did this on my '69. Not too dificult to do. the pedal box had to be redrilled on two or three of the six bolts.

In my case the only problem was the clutch pedal on the later box would hit the rear of the firewall before releasing. Had to re-profile the curvature of the pedal at a machine shop.

If you use the conical K & N filters there is just enough clearance. Didn't have to cut the spacers and I used HS-4's.


Luigi, what were the part numbers on those conical K&N's? I have those oval foam filters that Moss sells turned vertical and they clear, but it's time to go to the good stuff. Thanks in advance.

Sorry - Haven't had time to get on here sooner. They are Moss #222-985, about $66 each. I know, kind of pricey but considering I haven't had to change them ount in the years I've owned them, they've actually saved me money. K & N asks that you clean them about once a year, respray w/ their oil spray and reinstall. Supposed to work better as it gets dirtier.

This thread was discussed between 06/03/2006 and 09/03/2006

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.