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MG MGB Technical - Carb Conversion

I have been reading the archives about converting the ZS carb in my 77b to dual SU's. I have an opportunity to pick up a set for $80 canadian, allthough they need a bit of work because they're sitting in a car that hasn't run since 1989. I was just wondering if the carbs from that car (1973 mgb) would work on my car, and if it is fairly straightforward to swap the intake/exauhst manifolds.
Kate

Yes, those carbs will work in your car. In fact, you'll find MANY threads in the archives about the conversion. You will need the exhaust and intake manifold along with the carbs, and a set of air filters and housings. Along with that, the front exhaust pipe too, or now would be a great time to add a header!
Good luck.
Jeff.

Jeff Schlemmer

Kate,
I agree with Jeff.
You probably won't be able to use the original type air filter housings as they would interfere with the brake booster. K&N and other aftermarket filter companies do have filters that will fit. If you use the stock exhaust manifold try and get one that has the same flange height as the intake manifold. Makes mounting to the head much easier.
As to using a header you'll get pros and cons on it. I used the stock exhaust manifold as the BMC engineers designed this part very well.

Mike
'79B
Mike Janacek

Kate-
Yes, swapping the intake/exhaust manifolds is a fairly sraightforward job. Since they're coming off of a 1973 car, we might presume that they're SU HIF4 carburetors, but let's play it safe and cover all of the bases- As Mike pointed out, be sure that the thicknesses of the flanges of the manifolds are the same, otherwise you'll find yourself fabricating custom half-moon shims. There are actually two different exhaust manifolds. The one used with SU HS4 carburetors has a flange thickness of 7/16" and the one used with the HIF4 carburetors has a flange thickness of 9/16". The intake manifold for the SU HS4 carburetors has no provision for a vacuum take-off for the distributor, while the intake manifold for the HIF4 carburetors does. Each intake manifold requires the use of a different distributor. If the seller is including both manifolds along with the carburetors, then $80 Canadian makes the deal a steal, even if the carburetors are bad!
Steve S.

Kate, Steve's advice, as usual, is precise and correct. He makes a very important point in the second to last sentence, which I hope you picked up on. Try to get the matching distributor off the '73 you are taking the carbs from, then you will have a complete conversion. I assume that the intake/ exhaust manifolds are either available or, hopefully, included in the deal, as you need them. Will the seller do the parts removal, or will you? DO you need help?
Ken R
Ken Rich

Steve,
I recently bought a new distributor for my 77b, and the carbs are HIF's, will these work together?
also, does anyone know of a website that has pictures/instructions of how to go about converting the carbs?
Kate

Ken, I will most likely be removing it myself, but I've got someone to come along and give me a hand.
Kate

This thread was discussed on 02/03/2002

MG MGB Technical index

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