The Lotus twincam can take a lot of temperature before anything
bad happens to it.
For reference, the Ford Cortina Modified By Lotus that I
used to run had a very similar setup -- 1558cc, twin 40DCOEs,
Sprint header and D-type cams, Corsair V4GT gearbox, but
that extra-sexy body and a good, reliable solid axle with
leaf springs :-). I also had a dry sump, and acquired a
rebuilt bottom end after I learned about oil systems without
bypasses. I also learned what rod knock sounded like...
Anyway, this car had had an electric fan installed at some
time, and since the Lucas stuff was the most reliable on this
particular car, the fan switch and thermostat went out on a
semi-regular basis. No problem as long as you kept moving.
One night I started the 17-mile commute home and noted that
the traffic was worse than usual. As in dead stopped all the
way home. (It turned out later that a tomato truck had
overturned at the intersection of the 101 and 405 freeways,
which any southern Californians know as the second-busiest
interchange in the country; there were apparently 40,000
tomatoes covering something like 18 lanes of freeway in four
different directions.)
Well, my progress in the Dagenham Dustbin was to creep along
in first gear for ten minutes or so, till the water temperature
pegged the gauge -- I think it was 240 F but I can't recall
now. Then I'd stop the car, raise the hood, and wait ten minutes
for it to cool down. When it got under 180 I'd start again and
repeat for three hours, or till I got home.
I took the car in to Lotus John in Canoga Park the next
day. There was no damage to the engine from the constant
near-overheating (I never let it boil) and John said that
the engines were surprisingly tough. We did $300 worth of
rewiring on that visit, if I recall, including installing
a manual override switch for the electric fan.
As for why the car is getting hotter, try cleaning out
the radiator -- that is, cleaning the cooling fins as well
as flushing the coolant. (You can also try using a higher
percentage of water to antifreeze if you're concerned about
heat dissipation; we've covered that recently but I'll
recap if you don't recall.) My mom had a problem with a
280SL that was overheating badly, and since this car also
had an aluminum twincam head (it's not the SL you think it is)
we were concerned. Turned out that the radiator was externally
blocked with bees, and no air was passing over the core.
Good luck, both with the car problem and in Kansas!
--Scott "who now dreams of Atlanta instead of Salina" Fisher
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