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MG MGB Technical - Weber conversion

When converting from the zs carb to a weber on a 77B, what does one do with the brake servo hose that runs to the existing manifold as well as the anti run hose? Can the existing heater pipe still be used and run along side the header as well?
JCH Hibbard

Depending on which brand of intake manifold you have, there will either be a hole drilled and tapped for the fitting that is between the factory manifold and the flex hose to the brake booster or there will be just a raised boss that requires drilling and tapping.

How to handle the water plumbing is a personal preference item. My intake manifold is water heated and I run a line from the rear of the cylinder head to a T fitting. One end of the T fitting goes to the line coming from the heater, the second goes to the intake manifold. From the front of the intake manifold, there is a line that is plumbed into the lower radiator hose.

The rear water outlet on the late model cylinder head can be, if one desires, covered off using a blanking plate and a gasket. A reasonable solution if one does not have one of the water heated intake manifolds. I wrote up how to make a blanking plate some years ago using the original water take off as a pattern and a piece of 1/8"-3/16" steel flat stock. I think Moss has now had the design replicated for a reasonable amount of money.

If you blank off the rear water port, you would simply run the hose forwards to connect to the lower radiator hose. This can be done either by simply running a long length of hose or by using the copper bridging pipe used on some of the earlier engines. A length of copper pipe having a 1/2" outer diameter, along with a couple of sheet clamps to hold it in place would work well for this. I simply run a long piece of hose myself and have not had any problems when setting up that form of conversion.

Make sure you connect the front tappet chest cover to the 90 degree "elbow" pipe at the bottom of the air cleaner.

Les
Les Bengtson

Yea as Les shows its pretty straighforward. Not too much of a hassle. Just have a hole tapped into the manifold for the brake servo.

Do you know what jets you are using for your weber? If not there are some good recommended settings on the BBS ARCHIVE and also on the internet. Just curious, are you using manual, electric choke etc? If you are having trouble finding the jet size for an mgb please feel free to email me. Now is obviously the optimal time to be switching out jets etc while the carb is not mounted. It is the most important and potenially frustrating part of setting up your car. Its good to have all the info infront of you and jets installed ahead of time to get your car running in your desired target area with minimal time swapping out jets if it in fact needed. You will be pleased with the results and maintain some sanity. Not sure how much knowledge you have but an uprated fuel pump may be required.

Thank You,
James
James

This is how I did mine. I drilled a hole for the brakes servo and also some holes for the smog equipment. It works fine with no ill effects and it passes California smog with no problem.
JC Nelson

This thread was discussed between 15/07/2008 and 24/07/2008

MG MGB Technical index

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