Shutting it Off Before Getting it Going: Battery Cutoff Switch

It may seem counter intuitive at first, installing a shut off switch when my goal is to get things going. In my view its like working on your brakes before tuning the engine - make sure you can stop what you get started. Also, given my inexperience with wiring and the age of the car, the battery disconnect is a quick and easy modification that may some day save your bacon (or wire loom). It may also prevent the car from being stolen by a thief of less than average intelligence.

There are few materials to buy. I purchased a battery cutoff switch from Waytek wire for under $18.

Update December 2010:
This is the switch at Waytek: http://order.waytekwire.com/productdetail2/M37/44029/MASTER%20DISCONNECT%20SWITCH%20%20%203/8/
Price is now just over $21.00.

At that price I was was pleasantly surprised by the quality of the keyed switch. The face plate was around $1, with a minimum purchase quantity of five. My only complaint was the component was out of stock. Be careful when ordering and specify in the comments field on their web page to "ship together" you will get billed for separate shipping when parts are out of stock.

The grounding wire (red) is from my local Advance Autoparts and is for lawn mowers! Astley's 'MGB Electrical Systems" recommends a minimum of 6G, shorter than 18 inches. This one is 6G and 20 inches, so I'm pretty close. The grounding strap for a Harley Davidson would be ideal.

I located the switch on the bulkhead behind the passenger seat, an easy reach from the driver seat. Don't you just love how everything is "within reach" in these little cars! I drilled larger hole first, then used the face plate to orient the switch for the drilling of the second, smaller hole seen on the middle right. I consider this the primary use of the faceplate: solely as a locater for the smaller hole. Do I really want to shout to a potential thief : "Hey! Don't forget to turn is on if you want to steal the car!" Then again, who would want to steal this mingy thing anyway? Plus, it is keyed, so taking the key would then only indicate that they had to bypass the switch. Okay, I'm still debating the use of the face plate...
View from inside the battery well. Black wire on right goes to negative post on battery. My new red (lawn mower!) wire on left goes to ground (not shown).
Could they have made it a tighter fit? Battery in place, wires all over the place. That's the negative post on the left that loops around the compartment and to the switch. Positive on the right goes down the front of the battery and under the car to the starter in the front. All done! To the left of the key you can just make out the small post on the switch through from the back and helps anchor the switch in place. I will put a similar switch in the LE.

Carburetor Rebuild

The car would start easily, then falter as soon as the accelerator was depressed. It seemed like a carburetor problem. The GT has a 32/36 down draught Weber DGEV (electronic choke). Upon opening the bonnet the first question was: "WHY? Why did the previous owner paint the air filter with red primer???" Or is that just really bad red paint? I can understand wanting to pait the cover. Weber air filters are poorly chromed and tend to rust,...but why not some rattle-can silver or a gloss black?
There was also a small leak from where the carburetor mates to the manifold. Dripping fuel so close to the hot exhaust manifold is a GT-inferno waiting to happen. That gasket needed replacement before attempting to restart the car. With two good reasons to remove the unit it was time to get going. The bay looks ratty but we're not going for "pretty" at this stage of the game.
Sure enough! Lots of rust had made it past the fuel filter and into the float bowls. It was likely clogging the jets and who knows what else. That's not just "varnish" from stale fuel, but actual rust grit from the old tank.
It was time for a complete rebuild so I purchased a kit from Weber Carbs Direct . The full rebuild kit was just under $25 plus shipping. I also purchased the top filter housing, air filter, and cover for an additional $20.00. Painted cover be gone!!

With the help of the Haynes Weber carburetor manual the tear down and rebuild was straight forward. I took lots of pictures and placed all the pieces in labeled sandwich bags to keep everything separate.

Here is it after cleanup that included a soak in carb cleaner and polishing of the air intakes and float bowl. Reassembly is well underway in this picture.
Now the prettiest thing in the bay, the carburetor is installed back on the intake manifold. No connections yet - I still have some other fuel-related work to finish after reading an article in the latest issue of MGB Driver magazine where Dave Dubois has an excellent article on fuel system improvements.
Next up: Reconnecting the fuel, air, and electronics for the carburetor, plus my final improvements to the fuel line. More on that in a week or two!