> Function is more important than price, obviously, so is it worth
> spending the
> extra money, or is the solution of a plug with a 3/8th's hole as good or
> better to ensure proper engine cooling?
Terry, there are lots of opinions in this area, and very few hard facts.
Here are a few of each :
IMO, neither the sleeve nor Teri-Ann's fix are necessary for a cooling
system in good shape otherwise. There is evidence that even the factory
came around to this view eventually ... late TR4s were delivered with
non-sleeved thermostats and the bypass open.
When I was having chronic overheating problems with my 59 TR3A I
experimented with a open bypass, blocked bypass and restricted bypass. I
could discern no appreciable difference (except for how the blocked bypass
behaved at startup). I tried the same experiments again after fixing the
overheating problem (recored radiator), again no appreciable difference.
At this point I run a fully open bypass with a non-sleeved thermostat, and I
never have overheating problems even in extreme conditions (like over an
hour at 100+ mph in 100F temps on the way home from VTR 2001). I do have
some other mods, like a modern Modine core in my original radiator frame,
with no crank hole (didn't want to pay extra for the hole); but I do not
believe they are essential to avoid overheating at speed. The Hayden
electric fan does help a lot with overheating in stop-and-go traffic, but
here the issue is clearly airflow through the radiator, not water flow.
One of these days I'll borrow a multi-probe thermometer from work, and log
radiator entry and exit temps. If the outlet is appreciably cooler than the
inlet when the thermostat is fully open, then it's possible that blocking
off the bypass might increase cooling just a bit. However, I think the
difference in temp from inlet to outlet is going to be just a couple of
degrees, which means blocking the bypass can have only a tiny effect.
Be sure the cardboard air duct is in place, and in good condition. The
factory apparently did not install these on early 3A's, but I believe they
were an approved retrofit. Don't recall the change-over offhand, just that
TS39781LO is before. (And yes, it was made in late 58 but during the 1959
model year.)
Randall
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