All the stuff after the engine that gets the V-8s power to the wheels
has to be upgraded for a high HP conversion to be successful. I nearly
did this conversion back in the '80s when you could get a Buick 215 for
$250, but sanity prevailed, and I passed after thoroughly researching
the issue.
The LBC rear end won't handle 250 HP. It will bust just when you are
trying to beat the pants off that Corvette or Z-3 driver at the green
light. That takes all the fun out of it!
Not only that, the ratio is too low at 3.9/1 for highway driving,
particularly without a five speed gearbox, and don't even think about
transferring 250 HP through your MGB gearbox. A 3.07/1 ratio is
recommended by one current expert, Roger Williams, who's 1995 book "How
to Give Your MGB V-8 Power" is the definitive book on the subject.
Unfortunately, he is in Britain, and he specs commonly available British
parts for the conversion, such as the Rover SDI rear axle and drive
shaft, which still needs expensive "narrowing" to fit the MGB.
I have a copy of a conversion guide titled "MGB Plus" written by someone
in 1985 located in Vancouver, WA. The author wouldn't put his name on
it, just a PO Box long ago canceled (probably afraid of being sued!),
but it covers the subject very well and uses American components, albeit
from '70s and '80s vintage cars. He likes the 5 speed Borg Warner T-50
transmission used by GM, and has recommendations on rear ends as well,
but they too need expensive narrowing to fit.
BTW, the MGC rear end is the correct 3.07/1 and a drop in fit, but just
try to find one of those!
This is not an easy conversion to do right, but if you keep the V-8 in
the 150 HP range you can probably get by with your LBC tranny
(preferably OD) and rear end, but forget about boosting the power any
higher, the other drive line bits just can't take it. This is the
simplest way to do the conversion. Who knows, someday I still may drop
in a modern (if you can call an engine designed in the '60s modern) Land
Rover fuel injected V-8 just for the heck of it, but they are a bit
pricey.
Also, brakes will need to be upgraded, as will your driving skills if
you pull this conversion off. Sign up for a Bondurant driving class
before you take this machine on the road!
Stuart MacMillan
Seattle
'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)
Assisting on Restoration (and spending OPM):
'72 MGB GT (Daughter's)
'64 MGB (Son's)
Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT
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