Friday, March 13, 2015

Cheap and Simple M.G.B. Modifications for Speed & Handling.

Mine was yellow, a bit more faded than this one.

Ian Cooper

When I bought a 1971 MGB roadster in about 1978, I was an eighteen year old kid. Lots of guys liked sports cars back then. There were a lot more of them, and even as fourteen and fifteen year-old kids, naturally we dreamed of the day we would turn 16 and get our beginner’s license.

Over the course of the seven or eight years I drove the car, I blew the engine, burned out a clutch, scored brake rotors when the brake pads wore down to the metal and I was a hundred and forty miles from home. I had all sorts of adventures in that car.

The car was modified to some degree by the time I was done with it.

The original motor had an air pump for pollution control. On someone’s suggestion, a guy with an M.G.B. G.T., I removed the air pump, the separate pulley belt for it and then used five-eighths national coarse pipe plugs to fill the holes in the head.

Purists hate to see you do that sort of thing. I wanted to race. It was my big dream in life. I read Road & Track, Rob Walker’s F-1 coverage and all the road tests—we read tests of cars we could never hope to own, but guys of a certain age drool over a red Countach.

By the time I was done, the car had an aluminum hood. Once you’ve taken the motor out once or twice, you quickly realize that the sealed and bonded ends of the oil cooler hoses are a pain in the butt because the hoses go through flared or rubber-ringed holes in the radiator cross-piece. You had to take it out sometimes In the M.G. it's easily removable with a few bolts. The solution to this was to cut the metal part of the pipes, and then substitute Aeroquip hoses. The oil pressure in that car was good, fifty to seventy pounds per square inch depending on engine speed. Not knowing all that much about such things, I used double hose clamps. I used a fairly big clamp which meant that it had a fairly big screw to tighten it. I could use a fairly big screwdriver to tighten it properly.

Another modification happened by accident. I was in Delhi, working at the News-Record, and the car had charging problems. The alternator was shot. I needed it for work, M.G. parts were expensive. A guy at the Canadian Tire store in Delhi suggested changing it for a Chrysler alternator. I thought he was nuts until he took me out in the parking lot and showed me how he had done it to his red Triumph Spitfire. It took a piece of flat-bar, a couple of holes, used the same belt, and now produced seventy amps where the little M.G. unit would do thirty-five.

On that car I put Hooker tube headers. I had a Supersprint free-flow exhaust. When you look at the ads in magazines, (online nowadays), they make claims. Guaranteed increase in horsepower, anything from ten to thirty-five percent. It’s probably best to assume lower numbers. You’ll talk about it and your friends will try and shoot you down. It’s best not to make extravagant claims. The combination sounded good and the engine probably did rev higher and produce more power. The engine blew one day at over a hundred miles an hour, and that’s how I ended up with an engine from a 1968 M.G.B. that I pulled out of a back yard on Pine Street and we towed home on the end of a rope.

What I did next, before sticking that old motor in my car, was to pay a guy just down off Vidal Street to rebuild the block properly. Then I did a little porting and polishing on the cylinder head.

I had never done it before and I’ve never done it since. I didn’t go too insane. Going mad in there will create thin spots. Coolant flows through the heads and uneven thicknesses in port walls leads to uneven cooling and heating cycles. This will result in hairline fracture and eventual failure. I just tried to match up the profiles where the exhaust ports met the manifold. I smoothed it up, not to a mirror-like shine, but matte. I did a similar process on the intakes, which were round—the exhaust ports were little rectangular holes inside the larger round tube of the header.

When doing the cylinder head, we milled her down about 0.030”, something rational like that. That was three passes of ten thou each.

I took the heavy and boxy old M.G. air cleaners off and made my own. There are small, flat but cylindrical filter elements. I took two round plates of sixteenth hard aluminum. The outer plate needs a couple of holes for the bolts, and the inner plate had the hole to match the carb plus the same two holes for bolts.

The other thing with the M.G. or any small car is weight. On a roadster, the roof comes right off along with a little folding frame-work—the stays. You can leave that at home. The bumpers were easy to remove. That saved some weight. The air pump weighed a few pounds. When the rug was shot, I took it out. A rotten old rug weighed something. I switched from two six-volt batteries to one twelve-volt. I got rid of the original three-blade wipers and used a two-blade system from the ’68. 

The triple wiper system was in response to improved safety regulations of the era, something to do with having ‘a minimum of 100 square inches of swept area’ or whatever it was back then.

The M.G. was a fun car for a young guy. You could look up under the dashboard and find the four bolts. You could remove the windshield. I took the front fenders off. I propped her up on an angle of forty-five degrees once to do some work to the chassis, which had some rot when I got it.

I took the engine and transmission out, changed the clutch plate and then put it back in the car again. I was alone, just me, a set of chain-falls and the car.

Throw in a little bit of aggression, and that was a pretty quick little car for its time, its place, and its budget.


Note. By removing ten percent of the weight of a car, you get ten percent more power for free. It will accelerate ten percent faster, go ten percent faster, and use ten percent less fuel. Not only that, but the tires have to pull ten percent less vehicle through a turn, as well as under braking. Also, by extension, the spings are now ten percent harder (relatively speaking) and the shocks ten percent more capable of damping out major wheel movements. Braking distance will be reduced by ten percent. This is not an extravagant claim but the result of simple physics.

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