This is a list of technical responses to the questions asked over
the past week.
WHEEL SPLINES: When the splines are new, they're sharp; when
they're worn, they're rounded; when they're REALLY shot, they're sharp
again. Measure the spline diameter to find 2.450" NEW, and 2.400 ABSOLUTE
minimum for safety. Have an associate stand on the brake pedal and attempt
to rotate all four tires BEFORE you tighten the spinners. There should be
NO freeplay. Both the hubs and the wheel splines wear; check the wheel
splines by sliding your finger, from the outside, in along the splines.
You will feel a reduced diameter at the inside lip. Make a value judgement
based on the five wheels you check.
STEERING WHEEL NUT: MGAs and early MGBs, as well as early Midgets
use 1 5/16". I tighten them by feel but guess its about 30 lb-ft. To
remove a steering wheel, back the nut off to the end of the treads. Person
#1 sits in the vehicle with a double faced hammer in his left hand, head on
the nut while gripping the hammer and the wheel at about 8:00. He also
grips the wheel at 12:00 with the right hand; and he jams his knees under
the wheel at 6:00. At all three positions he tries to pull the wheel off.
Person #2 has a LARGE hammer (3lb eg) and strikes #1's hammer. Never hit
#1's hammer until Person #1 says "Again." The wheel will pop loose after
several solids hits. Hello Ed!
CHOKE CABLE ABUTMENT: As odd as it may seem to the novice, the MGB
and MGC choke cables are held fixed at their ends. It is the outer
housing, the sheath, which moves against the choke cable abutment.
Throttle linkages are arranged as this in at least some Morgans.
CYLINDER HEAD AIR INJECTION PORTS: This is a 7/16-20 UNF or SAE
thread into the cylinder head. You can use hex driven allen screws, grub
or set screws, 1/2" long to give the cylinder head a finished look after
removing the air injection manifold.
MGB EARTH STRAP: A fixture at the left front motor mount from 1956
thru 1974, it was moved to the RH gearbox mount in 1974/2 to 1979, then it
moved to the firewall to the rear engine bearing plate in 1980.
IGNITION WARNING LIGHT: This lamp indicates the difference in
voltage between the battery and the generator/dynamo. It should illuminate
when the ignition is turned on, and should be completely extinguished over
1000 rpm. In the case of glowing more and more brightly then "winking
out," the problem is the voltage regulator or the regulator's ground
connexion. In the case of an alternator (68->) a dimly illuminated
ignition light at higher speed indicates a faulty diode in the rectifier.
COMPRESSION: Do not trust your compression gauge for accuracy, but
only for precision. Look for a range of no greater than 10%. If an engine
has lain fallow for more than several months, always run the engine for ten
minutes or so BEFORE judging the compression.
BALANCING ENGINES: I have rebuilt hundreds of MGA and MGB engines
and have never concerning myself with balancing. Never have I seen an
engine failure that I would attribute to lack of balance.
RAISING COMPRESSION: There is a balance between engine compression
and octane requirements. I have found that 8:0 : 1 is the best all round
ratio to achieve. If the engine has a higher compression than the gasoline
octane can support, more heat is created, and less power.
TD CORE PLUG: Remember that this entire engine is built in metric
form, hence the plugs are metric also. However, a 1 3/8 freeze plug works
perfectly! Clean out the hole into which the plug will fit, scraping every
last bit of old crust and goo. Place the plug into the hole DRY and use a
pair of hammers (qv steering wheels) to begin to flatten it, hence
expanding it.
LATE MODEL MGB FUEL HOSES: Change them to modern American fuel
line BEFORE you drive your car again! These old lines not only develop pin
holes, but rupture along their length! VERY VERY DANGEROUS. Also, plumb
out the "roll over valve" as these are now all leaking (some safety device!).
TOP COLUMN BUSHING: Especially on the 1970 -> 1976 MGBs, these
come loose, wear out, and need grease. Remove the steering wheel, remove
the column covers and switches, remove the "C" clip on the column within
the bushing recess, remove the screws that hold the bushing to the top of
the column and withdraw the bushing. Peen the aluminium housing around the
ball bearing race, liberally (I use that word with great caution) grease
the bearing, reduce the diameter of the end of the column with large
pliers, and reassemble. You will have eliminated that nasty movement.
MGA CLUTCH: Remove the engine only, NOT the whole works. To re-
install you DO need the alignment tool to properly centralise the disc. If
you remove the engine/gearbox assy, you may not need the tool, but I would
use it in the interest of time. If you have the gearbox out, be certain to
change the rear gearbox bushing -- it presses in and out from the RIGHT!
The TD/TD/A used the ten spline first motion shaft. The latest As and all
the Bs use the 23 involute spline ( a superior piece ). It is possible to
fit the MGB clutch assy to the MGA.
T SERIES RESTORATION BOOKS: Malcolm Green's, Horst Schach's, the
New England MG T Series Restoration Guide by CHIP OLD, edited by RL Knudson
John Twist's Technical Book for the XPAG Engine, and, of course, the
factory workshop manual.
HOSES - TUBES - LINES for the 77 -> 80 MGB: Hose from the radiator
diaphragm to the bottom side of the anti run-on valve. Hose from the anti
run-on valve to the charcoal ADsorption canister. Hose from the canister to
the valve cover. Hose from the front tappet inspection cover to the rear of
the Stromberg carb. Hose from the canister to the fuel tank purge line
(steel - right there). Hose from the canister to a steel line across the
alve cover, to the vent fitting on the rear of the Stromberg. Hose from
the intake manifold directly to the anti run-on valve. Hose from the
intake manifold to a "T" to the gulp valve. From the T a hose goes to the
TCSA switch on the brake master cylinder housing, and from that
transmission controlled spark advance switch to the distributor. Hose from
the small fitting on the top of the carb to the EGR valve just to its rear.
HISTORY of the MG Sports Car in Eight Chapters by Mike Allison.
Blair, can you E-mail your address so I can contact you on this one?
FAST FORWARD! John Twist, University Motors, VRHS43A@PRODIGY.COM
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