Re: Cooling system mods

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

Bob Ducker wrote:
> 
> Mike Wattam wrote:
> 
> > <snip> in other words, if your Stag is overheating, there IS a reason
> > -finding it might be more difficult!  My guess is if all else fails,
> > suspect head gasket weep into the cooling system.  This aids steam
> > pockets and stops circulation sometimes.  A Stag foible is that if
> > there is air/steam, it will 'rattle' audibly through the heater matrix
> > if the water valve is partially open.
> 
> Greetings...
> 
> My last comments about Stag cooling were based on what I thought was a
> general consensus on the inadequacy of the basic design. Based on the
> response, that really doesn't seem to be the case, so now I've had to
> rethink my overheating Stag! The motor was extensively rebuilt right
> after I bought it, including a new crankshaft (one of the thrust
> bearings was missing), a new rh cylinder head, new pistons and all the
> other usual rebuild items. A couple of somewhat more unusual items, done
> in order to keep the original block with the car,  was the installation
> of jackshaft bushings and steel sleeves on all 8 cylinders to bring them
> back to standard size from a large overbore. The overheating is not
> really bad, but I can't use the air conditioning over about 95 degrees
> F. I may be missing something simple, but I'm also wondering if the
> sleeves may be a source of excessive friction, especially after warm-up.
> Has anyone had experience with sleeving a Stag motor after having used
> +.030 pistons? My version of the shop manual does not recommend more
> than +.020, but the pistons were made by AE, so I assumed they were
> (are?) commonly used.
> 

Hello Bob,
	Follows are a fairly comprehensive list of what some of those "other
things going wrong" might be.  You should agree that most are routine
maintenance.  I'd check most of them before you panic.  
	Some of the basics are:  Is the timing correct? Retarded spark causes
over heating, as well if your spark advance is not functioning. You are
using unleaded fuel (burns hotter), are there any vacuum leaks or are
the carbs leaned out to pass emissions, as both cause lean buring and a
hot engine condition.  If you can get away with it, adjust the carbs to
mid specification on the CO.  What mix is your antifreeze?  The best
heat exchanger is pure water, for the increase of boiling point and
lowering of freezing, we add antifreeze.  30/70 antifreeze to water
ratio is a good mix if you are not in a real cold climate, 40/60
somewhat better, 50/50 optimum for good hot/cold climate combinations. 
Here in Colorado, it goes over 100 degrees F in summer and below -20
degrees F in winter, with 10% humidity, plus being over 5000 feet
altitude, and sometimes driving over 10,000 feet altitude, water boils
at a lower temperatures here, as low as 180 degrees F at high
altitude.   This is one reason why a lot of Stags here have engine work,
or conversions.
	First, when was the last time you had the radiator rodded?  The "stock"
radiator, if 100% clean with 100% of the tubes and fins intact and
straight should perform okay for some climates, but not best for
climates in the Western/Southern US.  Which leads to the next question,
what radiator is in the car now?  Original was a staggered two row, or
as some call it, a two row "D", or a 3/2 row.  For your area of the
country, I'd have the radiator recored with a 3 or 4 row core.  My
recore job cost about $260 for a 16 fin per inch 4 row core.  Third,
when do things begin to heat up, running hard under load or in idle?  If
it is running hard under load, then the radiator is not doing it's job. 
If it is during idle, then it is the fan and/or radiator not
performing.  Chances are, if at idle, it is the fan/torquatrol unit. 
I'd had owners tell me that addition of the cowl, even in the UK, solved
their heating at idle problem. Contradictory to some claims, I know
several folks that had installed fan cowls and replaced or modified the
torquatrol unit and have stable idle temperatures.  It also appears that
the best solution for idle cooling may be addition of an electric
thermostatic controlled fan if you have the space.  Another option is
modifying the A/C fans to be thermostatic controlled, will help the idle
cooling.  Also, checkthe A/C fans to make sure that they blow through
the radiator towards the engine.  A swapped pair of wires will cause
them to reverse.
	I would also check real temperatures in your coolant with a real
thermometer, that is, one with numbers, and check the temperature
sending unit to verify if it is the right one matched to the Stag
temperature gauge. I do not mean to stomp anyone on their advice, but
there have been many offers of engine running temperatures from various
Stag owners, but with no numbers on the gauge, nor knowledge of the
ambient and engine loading, these are only a guess at best.   One
modification I've seen for real data is a capillary temperature bulb
mounted, and attached temperature gauge, in the radiator location where
the Thermostatic Vacuum Switch (PN611428) is located in the radiator. 
If you can get the vacuum switch removed without destroying the radiator
(it unscrews), most auto parts houses sell a full sweep temperature
gauge with numbers and capillary bulb that will screw right into that
spot, or with use of an adapter, for about $50.  Then you can see what
the real engine coolant temperature is.  You might be surprised to see
that what you thought was a hot/overheating indication on your Stag
gauge is only 195-200 degrees F.  The Stag engine just is a hot runner,
and it cranks off quite a lot of heat into the engine compartment. 
Heavy, thick Cast Iron exhaust manifolds sitting right under the
cylinder heads do not help matters much.
	So, before you panic, check out the other stuff first while enjoying
your Stag.

Regards,
Glenn Merrell
'73 Mark II Stag