Re: Radiator Options

["Glenn A. Merrell" <gmerrel@domain.elided>]

John R Dombey wrote:
>  I'm not sure
> if the fan clutch allowed the fan to wobble enough to catch the radiator
> strap (mine has vertical metal straps, I'm not sure why) or if maybe one
> of the engine mounts allowed things to move too much.  Either way, the
> rad is trash.  On to the query:
> 
> I know this has been beaten to death on these pages, but before I shell
> out my hard-earned cash, what's the optimal radiator configuration?  I
> seem to recall reading that a 5-row core was not great, but that some
> form or other of 4-row was better?  Or maybe modified flow?  (BTW, what
> exactly does that mean?).
> 
> The fan is toast too (and I suspect that the clutch isn't too happy
> either, although I haven't had a chance to disassemble things yet), so
> I'll probably just replace them with an electric fan with thermostatic
> control.  Any comments?
> 
Hello John,
	I hope your e-mail box is quite large in order to accept all the good
advice you are going to get!
	Lets start with how the Stag was cooling with the existing
configuration.  
1.  What type of radiator is in the car now?  If it was being held in
with straps, I suspect that it was an oversized core like a 5 row high
effenciency, which is too thick to be installed properly without cutting
sheet metal, so it was strapped in place.  A thinner radiator will most
likely perform adequately.
2a.  Was the existing system performing adequately?  If so, duplicate
the system, but using no more than a 4 row high effenciency.  The core
should fit between the thickness of the side tanks, thinner by about 1/4
inch on both sides.
2b.  If the system was not performing up to your expectations, and you
do not care about originality, then delete the existing fan and clutch,
recore the radiator with a 3 or 4 row high effenciency, and install a
good quality 16 inch cowled electric fan with a thermostat.  If you
install it on the engine side of the radiator, it will have less bug
guts to deal with, but either side is fine, unless you have A/C.  This
configuration will net you a quieter cooling system and slightly more
horse power.

some Radiator configurations (end view of core):

Standard     Uprated         Uprated        Uprated
2 row        4 row "D"Type   3 row"D"type   3 row hi-eff
|--|          |-- |          |- -|          |---|
|--|          | --|          | - |          |---|
|--|          |-- |          |- -|          |---|
|--|          | --|          | - |          |---|

Uprated       Uprated
4 row hi-eff  5 row "D"type
|----|        |- - -|
|----|        | - - |
|----|        |- - -|
|----|        | - - |

High effenciency radiators have both a higher "fins per inch" than the
standard Stag radiator, giving more cooling surface area, usually about
16 fins per inch, and a more dense exchange mass.  The standard
radiators now-a-days are about 12-13 fins per inch.  The core rows have
the fins attached to them in a zig-zag between the adjacent rows.  The
standard Stag radiator had "gills" that ran the vertical length of the
core in a single metal sheet, which is much more expensive to
manufacture.  "Modified Flow" is any staggering of the rows, not in one
plane, like the "D" Types.
	The arguments abound for and against radiator types, expensive
incomplete and inclusive testing, fan configurations, etc.  Experience
dictates that the original Stag cooling was not sufficient to cool in
some climates at idle, and the same system being quite sufficient in
other climates.  If this is your experience, addition of a good quality
electric fan is the best choice with any of the uprated radiators.  If
the system was performing adequately and you want an original Stag,
replace it to its originality, fan, torquatrol(clutch) and
radiator...with fan cowls.
	In the end evaluation, it depends on whether your Stag is a concours
class, or daily driver, and how deep your pockets are!  

	It sounds to me like you are on the right track for a daily driver,
uprated radiator, electric fan, remove old fan and torquatrol unit.

Regards,
Glenn Merrell
'73 Mark II Stag, USA Model, LE23398U