> Is anyone aware of the fact/myth that MGB engines should be
> run two quarts over full (oil level)?
It's somewhere between verifiable folklore and fact. The B Series
engine has always had a half-baked oiling system. Originally, it
was not meant to have a full-flow oiling system at all; the filter
would pick up some random portion of the oil in the sump and run
it through, figuring that eventually it would all get filtered, more
or less. (This was in the late Forties and early Fifties, when
50,000 miles was considered a long service life for an engine.)
Due largely to the fact that the newly founded British Motor Corp.
was planning to use this engine in their sports cars, it was decided
to spend the resources on running an external tube (like that on the
A Series) from the oil boss at the rear of the block to the filter
so that it would get a full-filtered system. The side benefit was
that this made it trivial for Abingdon to rig up an oil cooler.
Note that in its very first race outing, the MGB ran its bearings
in the 1963 Sebring 12-hour race and DNFed after something like
three hours. Talk about being part of a proud tradition... :-)
> I recently read an article
> written by drag racer Don Garlits where he answered technical
> questions concerning an MGB rebuild. Apparently he has owned
> several B's in the past, and said something to the effect of
> the engine cannot return oil fast enough to the sump, which
> results in fluctuating oil pressure while at highway speeds.
MGBs are known for being touchy in the oil level department. Running
low, when combined with high G-loadings (like, oh, Turn 2 at Sears
Point...) will definitely wear out your #2 rod bearing in seconds.
I'll send you the bearing shell if you'd like to see it...
> Does Big Daddy know what he is talking about? It seems I
> remember hearing something about the oil return problem being
> an inherent problem with MGB's, but I have never heard the cure
> of overfilling the engine.
Well, this is about half the reason that MGBs in the Olde Dayes and
vintage MGBs today run the factory competition deep sump oil pan.
It holds -- get this -- two quarts more than stock. (Coincidence or
CONSPIRACY???) It also has baffles that help keep the oil from
climbing up the side of the sump at 1.4 Gs (which is what modern
racing slicks will provide).
I'll bet that Eric Krueger's MGB runs a dry sump. This is a two-
pump system, one to suction the oil out of the pan and another to
pressurize the engine. Between these two pumps is a reservoir,
typically cylindrical and mounted vertically to minimize sloshing;
furthermore, you want to mount the dump tube at the top and the
pickup tube at the bottom, at tangents to the circle, so that the
centrifugal action of the oil keeps bubbles at the top and keeps
foam from getting into the pickup. If you don't do all these things,
you get to ride around the race track looking for pieces of your
motor, and eventually you end up doing something stupid like buying
a Z Car or an ITB Rabbit...
An intermediate system, and one I've given serious thought to, is an
Accusump. An Accusump is an oil reservoir that allows you to pressurize
the oil before starting. Also, if for some reason the oil sloshes away
from the pickup, the Accusump will kick in to make sure that oil stays
on the bearings till things settle down (or till you run out of oil in
the reservoir). It's particularly useful for starting your car, as it
lets you pressurize the bearings before they have to turn over. An
Accusump costs about $200 and is easily plumbed into an MGB's oiling
system, because of the external cooler lines.
> It does seem to make logical sense, but what about technical sense.
See above. This is a kind of shade-tree tip for MGB performance
that I've heard from other sources than Big Daddy. The worst problem
it might cause would be if the crankshaft slaps the surface of the
oil in the pan; this would sap a little of the power, but having
replaced worn bearings when my oil level got a little too low on the
track, I'll settle for durability next time so that I don't walk back
to the paddock 30 minutes into a 4-hour enduro.
> I have noticed my '77 B's oil pressure gauge will fluctuate
> sometimes at high speeds. I haven't noticed it in my '67 BGT's
> guage (since it hasn't been on the road enough!).
>
> Any comments on this subject would be welcome.
To recap:
- Yes, Bs are *very* prone to oiling system problems, though
usually when you run the kinds of G-forces that 1993 tires
can exert through a 1963 chassis on a 1953 engine oiling system
- Yes, I've heard it from other sources, including vintage race
engine builders, SCCA racers, and general M.G. mechanics
- The actual factory competition parts essentially do this, with a
few additional tweaks to make it even more effective
- The worst problem is that you might slosh up your existing oil
and maybe exert some additional parasitic drag on your crank,
in exchange for not having a rough copper bearing in your con rod
I intend to do something like this in my B when I get it fired up
again. I will definitely use a deep-sump oil pan on that car when
I rebuild its original motor as a vintage-race engine, whenever that
is. (When is La Carrera anyway, Daren?)
--Scott "Unless I really *do* build that hot-rod Volvo" Fisher
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