Hi
I thought I would follow up my previous postings about cooling an MGB now
that I have made some corrective efforts.
My major problem was returning home in traffic. (that is, when I manage to
return home before dark). I have an approx 1000 ft rise in the approx
10 miles from work to home. Another possible factor is the high elevation
(5-6K ft) in Albuquerque. Both built 69 and mostly-stock 68 MGBs show
similar overheating symptoms, particularly in the recent record-setting
heat wave.
For MGBs, both 16 row and 19 row oil coolers are available (stock is 14).
16 row ones are rather widely available. I have only seen the 19 row one
from Moss. While the 16 row one is labelled, I believe they are both by
Mocal.
These are normally mounted in front of the radiator and, particularly the
19 row cooler, obstruct air flow through the radiator. This is borne out
by experimentation in which the cooler is mounted below, rather than above
the flat front panel. This panel (in front of the radiator) has a box-section
member under it which is of structural importance. It is a relatively easy
change to invert the cooler and mount it to the same tapped holes from
underneath the box member. I just had to drill small notches for bolt
clearance and use longer bolts to mount it. The oil hoses therefore also
attach upsidedown. The hoses are long enough and can be arranged so that
they are not severely twisted to reach their new position. The hoses can be
covered with abrasion protection and routed under the alternator and
radiator. This implementation indeed does show improved cooling at speed,
whereby the temperature falls faster and farther when moving at a good rate.
A drawback is that the oil cooler fittings are now quite low (watch those
speed bumps!), being about the level of the front cross-member. I investigated
what it would take to turn the cooler over, still mounting below, but having
small access holes in the top panel to attach the hose fittings. Unfortunately
the bend of the hose fittings allows approx 2" and the thickness from the
top panel to the bottom (of the box member) is just greater than that. It is
certainly possible to make up hoses with longer/different fittings (and
to reduce residual twisting strain) but its pretty expensive for high
quality ones. In this case one could consider non-BSP fittings and other
types of oil coolers.
The next step is to fit electric fans. I checked out the available fans
from local parts places (eg Hayden fans) but they have few options appropriate
for the small (approx 19"x10") MGB radiator faces. They are also pretty
expensive. I took the helpful suggestion of Matt Silveira on this list and
obtained fans from Scotts in Ventura CA (805-295-9340). They offer a dual
fan kit with thermostat, switches, etc and seem pretty good. Total about
$140. The "swirl" fans supposedly draw only 4 A each and have a
relatively high flow rate. I use two of the their 9.25" fans which mount
behind the radiator (pullers). Bolted together, they span from side to side
and it was relatively easy to make mounting brackets to the radiator support
bolts. I use one of the provided through-radiator attachments to secure the
middle. Wiring them up took awhile to make it clean and switchable from the
dash. The only other trick is to use a short spindle water pump with a single
pulley so there is enough clearance for the approx 2.25 wide fans. I believe
the puller arrangement is more effective. It is close, with a half inch to
spare, so I will be looking to install the late model trans mount/engine
stay-rod (as already changed on the 69) to limit engine front movement
under heavy braking. The result is that the car is much cooler, but still
more than I would prefer. During stop and go it is up to halfway between
"N" and "death zone", which is better than the previous justabout "death zone".
It does come down to "N" at speed. Note that the early pulley (without the
air pump belt track) is larger so the pump does not spin as fast. The only
drawback at present is that I need to improve the vibration isolation of the
fans. I used some rubber in the mounts but was not sure of the final
clearances. The dual fans eventually hit a mutal beat frequency that is
noticable at idle. My next step is to try and isolate them.
I'm satisfied enough with these fans that I will install another set on the
69. I will spend more effort refining the oil cooler installation. On the
68, the holes in the front valance provide lots of air flow to the cooler -
and everywhere else under the car. I have the ST air dam on the 69 to limit
undercar air pressure (surprisingly noticable difference) and need to fix up
some ducting to feed only the cooler.
Fr completeness I should mention that the radiator cores are the best and
thickest I could get that would fit the top and bottom tanks. This was last
summer's line of inquiry but I concluded that going custom with crossflow
designs etc were not necessarily going to be better and would require lots
of effort in radiator shroud fabrication, hose fittings etc. I might go back
to this in the unlikely event of having spare time and money. One thing to
note is that in the later Bs, the radiator inlet and exit are on the same side,
encouraging coolant to take the shortest and quickest path through the radiator.
When the header tank is off of the core, have the shop braze in a panel that
channels the incoming coolant across the tank to the other side.
John Sanders
|