An M.G. Locost Build
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February 22, 2012
Donor Thoughts

So we overhauled the carburetors last week. The first one looked to be in pretty good shape, not much varnish and a fully-sealed float. The needle and seat of the fuel metering valve seemed to be fine, all bad news since we really needed these things to be the reason the car won't run. One bit of good news, the float height had been set by a complete amateur. Way too high, hopefully allowing the float bowls to flood and dump fuel into the air intakes with abandon.

  Of course there will be parts left over
click to enlarge

We replaced the needle and jet, not because we thought they were bad, but because we'd already bought new ones. We were a little worried that we weren't able to center the needle, presumably (and hopefully) because this is one of those later, floating needle type carburetors that we'd never actually heard of before, but certainly seemed like a logical next progression in needle technology. In any case we set the floats to the prescribed height, polished the piston cover (a.k.a. "dashpot"), and put everything back together pretty much the way we found it.

Everything we wanted to see in a carb and more  
click to enlarge

A look inside the second carburetor was far more encouraging. Not only was the float set way too high, but the entire float chamber was filled with crud. And this was not your ordinary, everyday crud, but a sophisticated mix of fuel, varnish, and some kind of thick gray goo. This carb was much more fun to rebuild. Everything had to be soaked in carb cleaner, scrubbed clean with steel wool, and blown out with an air compressor. We carefully reassembled the thing with all new and like-new parts, and stuck it back on the car with its twin.

After buttoning up everything under the hood, I climbed back in the car, and with expectations suitably lowered I grimly pulled out the choke and turned the key. The engine roared to life on the first revolution. Incredible. We let it warm up a bit before releasing the choke, then adjusted the mixture on both carbs using the traditional screwdiver-under-the-piston method. They both needed a couple of turns in the rich direction, which was pretty amazing right there.

  The MGB enjoying its day in the sun
click to enlarge

Naturally, a miracle of this magnitude called for a test drive. The engine cooperated beautifully, and for the first time since we took possession of the car, we had a running M.G. We motored smartly down the road to the local park, where I hopped out and took a photo of the car basking in its old-time glory. Everywhere we went the car drew looks of appreciation from passersby, particularly the older folks, possibly more for the fact that the car was passing through their neighborhood, and not breaking down in the middle of it.

After a 10-mile drive we parked the M.G. in the garage and changed the oil. The gunk that came out was a lot blacker than it had looked on the dipstick, so it felt good to get rid of it and put in four quarts of brand new Mobil One. We drove the car several more times over the next two days, including a few trips to the hardware and auto parts stores, and every time it started and ran like a champ. It definitely needed the choke when cold, but warmed up quickly once out of the driveway.

With all that driving, we were able to make several observations about the car. First of all, the radiator leaks, coolant seeping out of the upper tank as soon as it's up to temperature. We'll have to try swapping in the eBay radiator at some point to see if it's any better. Second, the engine runs hot, the water temp needle creeping well above the N mark and halfway to the H in normal driving. That's around 200-210o. Maybe it's related to the radiator problem. Let's hope so.

Most of the gauges seem a little vague. The speedometer wanders up and down the dial, giving only a rough indication of your speed. The tach seems a bit low, especially at the higher RPMs. Oil pressure reads 75 cold, 55 warm, which we hope is close to reality. And the fuel gauge reads exactly a quarter of a tank too high, as evidenced by the fact that it read a quarter tank when we ran out of gas on the way home from the hardware store.

Running out of gas is hardly a new experience for me, and almost a fond memory in the M.G. Unfortunately I had long forgotten the main symptom of impending fuel starvation in an M.G., so when the fuel pump started racing as we pulled out of the hardware store parking lot—a lot shared coincidentally with a Chevron station—I dismissed it as a minor issue with the new pump, and headed for home. We almost made it. A brisk walk to a local 76 station had us back on the road in less than an hour, with a new red plastic gas container to add to our growing collection.

More observations about the M.G. The brakes are getting better, no doubt due to the front pads machining a clean surface on the rusty rotors. Steering is heavier than I remembered. Not a problem at speed, but trying to toss the car into a turn was more exercise than I would've thought. I blame the tires, 185/70s being a lot bigger than what the car came with. Of course the Locost will have 185/60s, but it'll also be lighter up front and have less caster. So we'll see.

The car is torquey. Sports cars today all seem to have peak torque in the 4500-5000 RPM range and up. The M.G. peaks at 3000, and you can really feel it. Decent power even down at 2000 RPMs. I looked up horsepower and torque curves for the 1.8L B-series engine online, and plugged the numbers into a performance calculator along with the diff and gearbox ratios. According to the calculator, if we can keep the all-up weight below 1600 lbs. our Locost will see 0-60 times in the 5-second range. That may not be super fast by today's standards, but it'll still be loads of fun.

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