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MG MGB Technical - SU Conversion, Air Filters & Brake Servo.

Hello all; I have a 77 B that is currently in several pieces after an engine fire. I plan on putting all the pieces back together despite comments to the contrary from just about everyone I know! (My 6 year old is getting in on the act now!)
I have read & re-read the archives and current post's regarding the SU carb conversion for the RB cars. I have decided on a twin HIF4 setup together with the head work frequently discussed here.
As a result of the engine fire, I have to rework/replace most of the engine bay components including the master cylinder, brake piping & pedal box. Since I have to address these components anyway, I am leaning towards reverting to a non-servo assist brake system that will give me more room for different air filter set-ups, allowing better breathing to take advantage of the carbs & headwork.
My question is what year master cylinder / pedal box should I obtain to make this conversion?
Will I miss the servo-assist?
Am I crazy for going this route?
I have been to the Autoist site that describes the conversion process & it looks fairly straightforward.
Based on all I have read here, I think in my situation this is a good option vs. using the conical K&N's that reportedly offer marginal flow capabilities and are a tight fit at best..
Thanks for any and all feedback!
Pat

Pat,

You'll probably miss the servo assist somewhat (a bit more work in the cockpit). That having been said, were I in your position and looking to replace my MC anyhow, I'd probably go with the same unit used on the later non-servo-assisted cars. Others will tell you what, if anything, will need to be done to the lines to the existing MC. In my case, my conversion was accompanied by a custom air box, which allowed me to use the original stub stacks (with some nice flow work) and a very large K&N filter to at the front to more than handle the air flow requirements for both carbs. AND it allowed me to keep the servo-assisted brakes, which on my B have a very nice feel. I just installed this setup, so I'm still fine-tuning, but it really is effective (I had a custom single-carb setup previously, which is well documented in the archives, that already allowed for excellent flow...the twin SUs definately provide better low end grunt thus far...after I finish my tuning [tax time is currently distracting me] I'll be able to detail everything, including top-end gains, at least by "feel"). I've had the head work and other goodies...amazing what these little engines can do.

So, I don't think you're "crazy" for considering the course of action you describe. If I had to trade off brake pedal feel (remember, they'll still function as well, as long as you apply the additional pressure) for performance, I'd go with performance...as long as I didn't have any problems physically pushing the pedal (and I personally wouldn't, but everyone's different). That setup worked fine for a '73, and even with a couple hundred extra pounds of bumper, it should work well for you. Have you tried the brakes on an earlier model to see if this would be right for you. I'll tell you this...if I had a '73 I wouldn't install a servo assist.

Have fun,

Barry
Barry Kindig

Of course, if your steering wheel and pedals were on the correct side of the car, there's plenty of room for everything.
Mike (very tongue in cheek)

My 1971 car has no servo assist on the brakes and I like the feel (everything on home market cars was fitted later than on US models). The pedal is very firm with a short travel. OK, so you have to press a bit harder than in a modern car, but after a couple of miles you don't notice.
M
Mike Howlett

Just go for the early 70's set up - standard master cylinder and remote servo.

You can locate the servo on the other side of the bulkhead using the standard bracketry.

You can also choose the level of boost you want up to about 3 to 1!!

You will lose the twin circuit braking but if it was good enough for the early Bs, what the hell!!

Chris Betson

Pat-
If you go to http://theautoist.com/ You'll find an article about just what's involved in converting to the earlier non-servo-assisted system.
Steve S.

This thread was discussed on 09/04/2002

MG MGB Technical index

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