At 01:56 AM 29/10/2010, you wrote:>Most seem to agree that a temp sender on both banks will give a more accurate reading of the overall operating temp of the engine (makes sense).
Pardon my ignorance, but what’s the reasoning behind placing the sender inside the thermostat housing?
With consideration to Normans mod, given your druthers, ideally, where should the temp senders be placed?
A.J.
The reason, A.J., is that Jaguar put tapped holes near the thermostats
for sensors.
You could put sensors at the back of the head, if you had a place to put them.
Well, that might just happen.
I have got a stepper motor AAV rigged up on the coupe V12.
Under manual control it can give 2000 RPM at 18 deg C coolant
temperature when fully open.
We are into spring weather so there will be no chance to test it at,
say, 0 deg C.
However, if it can do 2000 RPM at 18 deg C there should be a good
chance it will do at least 1000 RPM at 0 deg C.
I have made a controller for it which needs a temperature sensor
mounted on the engine.
For starters the sensor can be put on the blanking plate which sits
over the hole vacated by the OEM AAV.
Then I will be able to also read temps at the back of the head.
Richard Dowling, Melbourne, Australia.
1979 XJ-S coupe + HE V12 + 5 speed, 1988 XJ-S V12 convertible, 2003 XJ350
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In reply to a message from gregory wilkinson-riddle sent Wed 27 Oct 2010:
I can tell you why silicone hoses get a reputation…
It’s installation quality… You need good clamps to hold silicone
hoses… reusing greasy old ones is prone to failure…
Second… use care installing them. Tighten them down well and then
drive the car long enough to get it completely warm.
Now let it cool down and once cold retighten…
Feel that? Yep! They’d loosened up some…
Don’t over tighten them though… do it as suggested… tighten
heat up/ cool down and then retighten…
Also many hoses aren’t exactly right for Jaguar… a little
trimming might be called for and in at least one location you have
to be creative because they wind up being too short…
One other trick?
Eliminate hoses where ever possible. Use tubing! I roll a bead
around the end of aluminum tubing and simply use silicone hose to
make the corners. Very tidy looking and least likely to fail!–
MGuar
Wayzata Minnesota, United States
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In reply to a message from Dick Maury sent Mon 25 Oct 2010:
the early ones that have enough aluminum left
to roll over the seats
Dick - I am interested in the method used to roll material over the seats. Have you
fabricated a special tool to achieve this? Is it something that locates in place of the
valve or valve guide? Any idea of where I could get hold of a ready-made tool that could
do this or is it a special tool you have had made up?
Alternatively, do you think that careful peening - carried out in four places before the
head is finally skimmed - could be just as successful? Is there a danger the seat could be
displaced or loosened during peening?
Of course, the best approach is to try to prevent overheating in the first place and I
plan to tie the seats down in conjunction with Norman’s cooling mods. Perhaps tying the
seats down is a bit of ‘‘belt and braces’’ but I want the extra feeling of security this
gives.– http://www.XJ13.eu, C-Type, XJ13 in-progress
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In reply to a message from Ronbros sent Wed 27 Oct 2010:
Actually if you read about the creation of the V12 a great deal of
engineering and testing went into the heads there are several well
written papers on the subject and what they actually found out will
change your mind…
For example the 4 valve heads don’t really make any more power
than the 2 valve heads untill you get to RPM ranges that simply
aren’t used on the street…
It’s relatively simple to put the inline six head with 4 valves
per cyl. on it on each bank. (same bore spacing and was designed
at nearly the same time. That six cylinder engine is used as an
option in later XJ-S). However it doesn’t yield any real power
increase over what you can do for a lot less money with the 2 valve
heads…
If you use the large Bore pistons available 96MM instead of 90MM
you can then use a 2 inch intake and a 1.75 exhaust On top of the
six litre crankshaft you are now at 416 cubic inches and in racing
trim you are at nearly 750 hp. Plus it’s a cheap engine to build…
To date no 4 valve V12 Jaguar has gotten within 100hp. of that
a 4 Valve V12 is estimated to cost $100,000 on a one off basis…
while 750 HP can be built for under $20,000 in the 2 valve head
design…
It’s interesting that when Jaguar had a 4 valve head for their
V12 race cars they choose not to race it… The reasons were
simple… too much weight up too high on an engine that already was
too heavy… (not to mention the reliablity issue etc…)–
The original message included these comments:
engineered head for cooling,
IMO,when jag said dont make a 4 valve DOHC, the two guys
desgning said F$#It, and slapped the simplest head they
could on.
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In reply to a message from Kirbert sent Thu 28 Oct 2010:
Guys
I have just been remounting the modified front water
manifolds and I also demounted the rear ones to re-gasket
them. As a consequence, I noticed the hose to the heater
coming out of the A bank rear water manifold.
This started me thinking and now I have a question:
What happens to the A bank rear cylinder water temp and flow
when the heater is switched on and hot water zooms out of
the rear A bank manifold and goes through the heater and
eventually back to the radiator bottom outlet?
If the AAV was junked on B bank, the same outflow point
would be available there too.
Greg–
The original message included these comments:
Unless the area of the hose is less than tha area of the thermostat it
has no control over flow and placing any restriction in the hose
usurps the role of the thermosat which is a variable flow control
valve.
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In reply to a message from MGuar sent Sat 30 Oct 2010:
Correct MG, the only reason you can make more HP with the 4V heads
is that you can run it faster due to better breathing and lighter
valves. When we replaced the 2V heads with the 4V on the boat we
instantly went from 610HP to 850HP but with a corresponding
increase in RPM from 7410 to 8560 because HP is only a calculated
figure. HP is a product of torque x RPM.
And we built the 4V head for less than $5000 ex labour.–
The original message included these comments:
For example the 4 valve heads don’t really make any more power
than the 2 valve heads untill you get to RPM ranges that simply
To date no 4 valve V12 Jaguar has gotten within 100hp. of that
a 4 Valve V12 is estimated to cost $100,000 on a one off basis…
while 750 HP can be built for under $20,000 in the 2 valve head
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In reply to a message from gregory wilkinson-riddle sent Sat 30 Oct 2010:
all cooling sytems are a compromise because of cost, and variety of
operating criteria like climate, driving style etc. Because heaters
are only used in the winter they place no load on the cooling
system as such. If they did then ideally you would run a pipe from
both banks to a T, then to the heater core.–
The original message included these comments:
them. As a consequence, I noticed the hose to the heater
coming out of the A bank rear water manifold.
What happens to the A bank rear cylinder water temp and flow
when the heater is switched on and hot water zooms out of
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Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
68
gregory wilkinson-riddle wrote:
I have just been remounting the modified front water
manifolds and I also demounted the rear ones to re-gasket
them. As a consequence, I noticed the hose to the heater
coming out of the A bank rear water manifold.
This started me thinking and now I have a question:
What happens to the A bank rear cylinder water temp and flow
when the heater is switched on and hot water zooms out of
the rear A bank manifold and goes through the heater and
eventually back to the radiator bottom outlet?
In theory, it shouldn’t make any difference. Once the coolant has
passed through the head, it doesn’t matter whether it goes through
the thermostat housing to the radiator or through the heater core.
In practice, though, it can make a difference if the flow is
obstructed somewhere. Since the 1-1/2 pass radiator results in
somewhat more flow in the A bank than in the B bank – a difference
that can be magnified by a plugged radiator – ideally that tap for
the heater would have been on the B bank coolant manifold. It would
have helped equalize the flow between the two banks. Since I had
replaced my coolant connecting pipes on both sides with copper pipes,
I considered simply adding a tee into the copper pipe on the B bank
and taking the heater feed from there instead of the OEM location,
but decided it wasn’t worth the bother. Before I went to that level
of effort, I’d just convert to a single-pass rad.
– Kirbert
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In reply to a message from Norman LUTZ sent Sat 30 Oct 2010:
I’ll assume that you used the 4 valve heads from the 4.0 litre
engine? and not a new casting etc?.
The $5000 number you used, did that include have special pistons
made? Because that could easily cost about half of your
budget…Also may I assume you simply had the Cam profile reground
rather than use new billet cams to get the full lift possible?
I can see where about $5000 would buy the needed parts (barely
and with some really clever shopping) but the hours involved in
welding, making up the gear drives etc…Phhheewww!
Just for idle couriosity I would like to compare the flow bench
numbers on the 4 valve heads as you used to those the 2 valve
heads modified with 2inch intakes and 1.75 exhausts.
It would be fun to run my engine analizer to see the real net
differance at similar RPM…
I wish I had the budget it would take to make a V12 survive
10,000+ RPM that NASCAR Chevies are. IN fact if attention was paid
to the V12 I suspect that revs as High as 12,000 would be
possible… at That sort of RPM I supect the SOHC V12 would make in
excess of 1100 HP. Since NASCAR V8’s make 850+ hp nowdays that
would be exciting…–
The original message included these comments:
instantly went from 610HP to 850HP but with a corresponding
increase in RPM from 7410 to 8560 because HP is only a calculated
figure. HP is a product of torque x RPM.
And we built the 4V head for less than $5000 ex labour.
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In reply to a message from MGuar sent Sun 31 Oct 2010:
As you say MG labour, Phhhheeewww.
2 XJ40 heads $800, Honda CB4 valve springs $500, JE pistons $1200,
billet cams we machined, $2000 for grinding, rifle drilling and
hardening, $500 for cam cover castings, timimg belt pulleys, timing
belts and assorted bits. Total–
The original message included these comments:
I’ll assume that you used the 4 valve heads from the 4.0 litre
engine? and not a new casting etc?.
The $5000 number you used, did that include have special pistons
made? Because that could easily cost about half of your
budget…Also may I assume you simply had the Cam profile reground
rather than use new billet cams to get the full lift possible?
and with some really clever shopping) but the hours involved in
welding, making up the gear drives etc…Phhheewww!
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In reply to a message from MGuar sent Sun 31 Oct 2010:
Hey guys lets get back to cooling for this post.
The 89 conv that I recently purchased from Florida was a typical
vehicle that hadn’t been serviced by a Jaguar shop. Trans had never
been serviced, rack had no grease, tie rod boots disintergrated,
trans mount bush missing. The list goes on and on.
But I am going to fully document the cooling system and the mods
that I will be doing.
As recieved it was running hot, upon removing thermostats I found
as follows, ‘A’ bank 190F OE style flapper valve, ‘B’ bank 180F std
type w/o flapper valve, both had been drilled with extra bleed
holes.
Safe to assume that this vehicle had overheating problems in FL.
Installed genuine factory 82C thermostats and tested engine.
Ran at idle for 10 mins to stabilise engine temp.
Dash gauge reading steady on ‘N’. Ambient 19-20C.
Using a laser type reading thermometer, thermostat hsg. temp was 80-
82C, rear outlet of water rail was 112-114C. 30C+ HOTTER.
Awaiting return of radiator from shop after cleanout and test.
Am installing Stg 2 water rails, removing engine driven fan and
installing a twin electric fan system from a V8 ford, as I tend to
drive long distances thru the hotter parts of australia as well as
the occasional red line.
will keep you posted as I go.–
Norman LUTZ
HEIDELBERG HEIGHTS, Australia
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Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
72
In reply to a message from Norman LUTZ sent Mon 1 Nov 2010:
Excellent rundown of existing sit. My Jag has always been Jag serviced. My temperatures run exactly as you
state. I have a new radiator and new fan clutch. No overheating but on 100 to 110deg F days and running full
throttle up hill for half an hour at 75-80mph on a very steep upgrade, the temp gauge is at the top half of
the ‘N’. The needle never gets its top edge over the top edge of the ‘N’. Once it gets there the heat build
up is so great that on flat cruising the needle never returns to 1/2 ‘N’ or below but stays above that. So
not much reserve cooling is available.
I would be very interested to see what you can measure doing the ‘Lutz’ mods without the upgrade of electric
fans. If you could make this ‘in process’ run as you get to your final configuration, it would be much
appreciated.
I plan to do the ‘Lutz’ mod using restricting plates of .0625 or .03125 sheet stainless steel. I have a vice,
hand drill and a grinder and an extra cover to use as a template. So this should be pretty easy. I will wind
up going with double gaskets on either side of the restricting plates. 16 gaskets altogether.–
Ptipon
Modesto/CA, 90 XJS-V12 conv, United States
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In reply to a message from Ptipon sent Mon 1 Nov 2010:
I don’t consider the electric fans a cooling upgrade as such, there
will be no additional cooling applied. I am removing the engine fan
and replacing with a smaller electric one. there will still be 2
fans, one for the AC and one for the engine. My main objective is
to improve MPG. Ever since my first E I’ve replaced the engine
driven fan, if so fitted, with an electric one. After I wrote off
my first E I purchased a 289 Ford 4 speed falcon that was lucky to
get 16mpg. after I removed the engine fan and replacing it with an
electric one I immediately improved it to 20mpg.–
The original message included these comments:
I would be very interested to see what you can measure doing the ‘Lutz’ mods without the upgrade of electric
fans. If you could make this ‘in process’ run as you get to your final configuration, it would be much
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In reply to a message from Norman LUTZ sent Sun 31 Oct 2010:
Thanks for that tidbit Norman…
I’ve always used Isky Valve springs to get the higher tension
required… I failed to consider motorcycle springs… Gives me a
whole new area to research…
So you used timing belts instead of chains? Probably simplified
things a great deal…
Who did your cam grinding? I’ve used Crower over the years and
they have been great. Talk to Bruce directly if it’s outside the
ordinary. …
I assume it’s been a long time since you bought JE pistons for
$100 each? Prices lately approach $140-160 even using the shop
discount…
Still that’s extremely modest in costs… Hat’s off to you sir…–
The original message included these comments:
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Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
75
In reply to a message from Norman LUTZ sent Mon 1 Nov 2010:
I’ve been thinking about replacing the engine fan with an electric too before the ‘Lutz’ mod came along. I may
still do that. But first I want to get the ‘Lutz’ mod in but won’t get to that for maybe another 6 months so I was
wondering if there is the possibility that as you are implementing the ‘Lutz’ mod that you might make an interim
measurement of the change with just the ‘Lutz’ mod.
Currently I am doing a wire wheel rotation maintenance and that is taking about a month a wheel. I’m sending all
5 off, one at a time to get all spokes refurbished and the wheel trued. After 100k miles, typically one or more
spokes have been broken.–
Ptipon
Modesto/CA, 90 XJS-V12 conv, United States
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In reply to a message from MGuar sent Mon 1 Nov 2010:
CB4 run in excess of 10,000rpm. MG if you look at my album you will
see the engine. Our cams were ground here in Oz. Engine was built
over 10 years ago.–
The original message included these comments:
required… I failed to consider motorcycle springs… Gives me a
So you used timing belts instead of chains? Probably simplified
Who did your cam grinding? I’ve used Crower over the years and
I assume it’s been a long time since you bought JE pistons for
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In reply to a message from gregory wilkinson-riddle sent Sat 30 Oct 2010:
I think the point of Greg’s post was that another possible way to
get water from the rear of the heads would be the hot supply pipe
for the heater hose on one side and where the AAV is on the other.
Maybe more flow from the rear could be obtained-- by those of us
without the welding skills to modify the size of the existing water
rails-- by using these existing orifices and somehow plumbing the
lines back in up front.
Robert–
The original message included these comments:
them. As a consequence, I noticed the hose to the heater
coming out of the A bank rear water manifold.
This started me thinking and now I have a question:
What happens to the A bank rear cylinder water temp and flow
when the heater is switched on and hot water zooms out of
the rear A bank manifold and goes through the heater and
eventually back to the radiator bottom outlet?
If the AAV was junked on B bank, the same outflow point
would be available there too.
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In reply to a message from Ptipon sent Mon 1 Nov 2010:
wire wheels belong on bikes. Jaguar are too heavy and/or to
powerful for wire wheels. took them of my E’s back in the 60’s due
to too many broken spokes, probably due to my’‘energetic’’ driving.–
The original message included these comments:
5 off, one at a time to get all spokes refurbished and the wheel trued. After 100k miles, typically one or more
spokes have been broken.
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Ptipon
(Ptipon, Sonora, CA, USA, 1990 XJS, Conv.)
79
In reply to a message from Norman LUTZ sent Mon 1 Nov 2010:
The wire wheels came with the car 17yrs ago when I bought it. So… there ya go. Put 100k miles on them with no
no problems but as you know that is not a given with wire wheels. The thang is, I like em and I probably don’t do
enough hard driving. Just a lotta cruzing up and down California.–
Ptipon
Modesto/CA, 90 XJS-V12 conv, United States
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In reply to a message from Norman LUTZ sent Mon 1 Nov 2010:
Wire wheeels?
They are on my vintage race car and have been since about 1975.
The car’s top speed at Elkart lake is 155MPH and I dive into the
corners just as hard as that big old beast will go…
While Vintage rules prevent me from upgrading the brakes, I have
done a few tricks.(Use the tandem master cylinder from a XK120 and
you can’t believe how much of an improvement in stopping power you
have) Wheel Brake cylinder size are modified a bit from stock for
best effect too.
As a result of that tweeking when I dive on the brakes It feels
like my eyes are being pulled out of my head. I know I have to be
pulling at least a couple of G’s Cornering with the rules mandated
tires is unlikely to be at even 1. Same with acceration…
This is with racing tires and decades of racing! Some of the tires
I’ve raced with are really gummy (Before Vintage rules tightened up
in that regard)
I check the spokes for tension every time I replace the tires and
I have yet to hear a single note off indicating somethings
changed…–
MGuar
Wayzata Minnesota, United States
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