Tech Tips: MGB

As other classic ’60s and ’70s sports cars grow more and more expensive, MGBs are still a bargain at $5000-$20,000. It’s hard to beat their combination of classic, beautiful looks and exciting driving characteristics. Great support and parts availability also make these roadsters easy to own.–Steve Rollin

EXPERT:
Steve Rollin
Northwest Import Parts
10042 SW Balmer
Portland, OR 97219
(503) 245-3806

These cars can be divided into two main groups: years 1962- ’74 and years 1975-’80. Generally, we like to address reliability before performance. Early cars typically see the most improvement after receiving the following the upgrades.

The first is an electronic ignition conversion. Converting to a more modern system will eliminate points and condensers. At the same time, you can cut down on maintenance time and money. The stock exhaust systems are prone to rust, as many classic exhausts are. A good stainless-steel exhaust system won’t rust and will last a lifetime. This is one of the more popular upgrades.

Aluminum valve covers can help eliminate oil leaks. Bonus: They look fantastic under the hood. Early MGBs also came with a point-type fuel pump. Switching to a solid state fuel pump is more reliable.

Early cars, with their chrome bumpers and lower ride height, are typically more sought after. But the later cars really shouldn’t be discounted too much. If you have a 1975-’80 MGB, a 1-inch lowering kit will make the car handle and look better.

The 1975 and ’76 cars didn’t have a front anti-roll bar, and as a consequence they lean a lot in corners. With a few modifications, you can put on a 3/4-inch anti-roll bar to tighten up the handling.

The 1977-’80 cars had a distributor that was prone to leaving owners by the side of the road. Modern magnetic-pickup Pertronix distributors are reliable and have an advance curve suited to today’s fuels.

The stock Zenith-Stromberg carburetor and manifold were known to have problems, and many owners have replaced them with the twin SU carburetors from the early cars. Alternatively, a more modern Weber carburetor conversion works great and makes maintenance easier. Both swaps will result in more power and reliability.

If you rebuild your engine, be sure to use the earlier MGB’s cam and higher-compression pistons. If the cylinder head ever cracks, be sure to upgrade to an aluminum head for durability and performance.

EXPERT:
John Twist
University Motors
4571 Patterson Ave. SE
Grand Rapids, MI 49512
(616) 301-2888

There are five main factors that go into determining the health of an MGB engine: water leaks, compression, oil, oil use, and the condition of the camshaft.

Water leaks are usually traced to a bad gasket or bad plugs. If that’s the case, they are easily repaired in place unless the head or block is cracked.

Compression should be consistent over all cylinders. Faulty compression may be caused by a burned valve or perhaps by cracked rings. Both these issues are repairable in situ.

Oil pressure should be at about 60 psi when driving down the road. If pressure is low, it can be restored by adding a new filter and fresh oil, by working with the oil pressure relief valve, or by changing the rod and several of the main bearings. All of these fixes can be made with the engine in the car.

Oil use is almost always from faulty oil rings. Remove the head and sump, remove the pistons and rods, hone the cylinders, fit cast-iron rings, and you’re back on the road.

If you find that a lobe on the camshaft is worn away, it’s possible to change the cam without removing or disassembling much of the engine.

None of these conditions require an engine rebuild, but if your engine has several issues, then perhaps a rebuild is best.

The one big enemy of MGBs is rust. Having a new clutch put in can cost $1500. A new soft top costs $700. A complete lubrication costs $750. And a new engine costs $5000.

But these figures pale in comparison to the cost of heavy-duty bodywork. Rusted sills and associated oxidation damage can cost $1000 per side to weld, and that’s without paint! An excellent paint job requiring disassembly and reassembly of the body can easily cost $20,000. Keep that in mind when shopping for an MGB or just throughout ownership.

EXPERT:
Bill Shields
Carriage Craft
1615 Ridge Ave.
Reading, PA 19607
(610) 775-3228

When MGB owners find a worn camshaft, many like to search for performance replacements. However, our experience shows that this is often a mistake. The power gain is disappointing and drivability is lost. Much more power can be made with a cylinder head port cleanup and a valve job. These heads act like restrictor plates, so start there first.

If you do go for a cam upgrade, don’t go overboard. These engines like to run in the 2000-5000 rpm range. Changing the cam and moving it up to 3000-6000 rpm takes away the drivability and creates disappointing power gains.

Another common mistake made by MGB owners is over-stiffening the front suspension. These cars were built with a pretty soft front setup. Stiffening things up too much tends to ruin the drivability more than it helps handling.

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