<<What do you recommend for competition purposes in a hot climate? I mean how
many row cooler and anything else special besides the cooler? I was
considering fitting a 16 row cooler and a temp gauge but I know there are 19
row coolers available - worthwhile Bill?>>
First, to the guy that caught the fact in a previous post that the fellow was
measuring _after_ the cooler - well done, I missed that when I responded that
his temps seemed fine.
For the record, the best place to measure oil is in the sump itself, which can
be done by brazing a fitting onto the side of the sump after drilling a
suitable hole for the temp sender nose. The other easy way, is by installing
a 1/2" pipe thread plumbing 'T' fitting on the fitting that comes out of the
block from the pump on the right side, with the sender straight up, and the
other leg of the T pointing somewhere toward the filter head, i.e. down at an
angle that lets you screw the hose onto it. With this set up you are taking
the reading immediately after the oil comes out of the pump.
By the way, if you are doing this on an MGB, install it before you put on the
rear engine plate, or notch the rear plate to allow the T to turn until it is
tight. Earlier rear plates that don't extend past the bellhousing area are no
problem.
I have done it both ways in various cars, and have a preference for the T set
up. Any time you have anything going through the sump, there is a chance of
leakage, that it could get caught and ripped off, or both. I do continue to
use a bulkhead fitting through the sump on my daily driver (Fiero) for the oil
return from the turbo bearing, but it seals by tightening on itself, rather
than relying on a braze joint that can crack or become porous.
Now, back to your question.
The factory stock oil cooler on a late MGA, is one that mounts from the under
side of the panel in front of the radiator (no, I don't know why they did it
that way, but their logic sometimes defied sense - look at the factory MGA
front sway bar that installs above the bumper extensions instead of below,
where you could change it without ripping half the face of the car off, or the
Twincam engine that they fitted on the assembly line before the body, leaving
access to the distributor a lengthy "pull the wheel and inner panel"
exercise). That cooler is 11 rows.
The factory MGB cooler, and I believe the MGC as well, but my C is in storage
so I can't check it, is 13 rows. This functions very well for street driving,
even in fairly hot climates.
The older factory competition cooler is a 16 row. This is pretty good for most
racing use, although for really hot cars or really hot climates, the later 19
row is available. I use a 19 row in the TVR and a modified Mazda rotary that
probably has at least twice the cooling capacity of the 19 row, in the
Twincam.
It is _very_ important with the bigger coolers, to properly warm up the oil
before using maximum rpms. With the street cooler, things warm up reasonably
quickly, but with the competition sized ones, it takes 10 minutes idling in
the pits and one or two warm up laps to get up to temp. In cooler weather I
tape over a portion of my cooler so that it runs at the right temp when fully
warmed, and could probably get away with a 19 row in 80% of my races. It is in
the other 20%, when it is over 100 deg. out and everyone else is slowing down
(temperature rises sharply with increase in redline), that the big cooler
lets me continue unabated.
It is a mistake to run to big a cooler or to incorrectly warm up the engine,
if you do. I got stuck in one race a few years ago having spent every second
up to the race working on the car, and thus without a chance to warm it up.
What I _should_ have done, of course, was run the first few laps at reduced
rpm to get things circulating. What I _did_ was get into an almost immediate
battle with an old rival (Goddam Alfas), and ran to red line too soon. The
tremendous shear forces involved between cold oil and the bearing shell took
the centre main and spun it right around, flattening the locating tabs out. I
think that the bearings spun a few times, but the pressure only dropped about
15 pounds (suddenly, when it first spun) and I figured it was an ex-engine
anyway, so I finished the race (came second, I think, and not to the Alfa).
But I never made that mistake again. It trashed the block and crank.
I have little experience with the oil thermostats that can be used, but my
friend with the other TVR race car has used them and they seem to work
properly, so this might be a useful combination if you want a larger cooler
but also want to be sure that it warms up quickly.
A final note on coolers - the passages are fairly small and can trap bearing
material that passes through them when an engine blows. They absolutely must
be cleaned out before reusing them because the flakes of material, small as
they are, can float through the system in the new engine. They tend to collect
in the crank itself, in the crossdriilings and whatnot, preventing flow ant
trashing another engine. For those that don't know, the 3 main cranks, and all
5 main competition cranks are cross-drilled to allow flow to the inside of the
throws on number 2 and 3 to supply enough oil at higher RPM. The stock 5 main
MGB crank is pretty useless above about 6500 RPM unless it is crossdrilled.
The 3 main version are fine for oiling, but less longitudinally stiff, which
results in worn centre mains at high RPM, rather than thrown rods from lack of
oiling, as would be the case with an unmodified 5 main. Hobson's choice.
Bill Spohn
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