Ruby i running now!

finally,through you good people helping me, my sisters car runs fair,so far.
Is the correct timing mark on the crank damper 8 degrees before top dead center with number 6 piston ready to fire?
I will check that tomorrow. , Mark

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You are referring to ‘static’ timing, Mark, and I do not have that spec - what is the advance with the engine idling, vacuum disconnected? This dynamic advance varies with ‘US’ and ‘European’ - it relates to vacuum source…

Frank
xj6 85 Sov Europe (UK/NZ)
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I have performed the static timing procedure at 8 degrees btdc.So I checked the Haynes manual,it shows more like 16-17 degrees btdc for north american cars.Seems I have read from this forum,that 8 degrees was ok.I am just trying to get ruby running as smooth as possible.I live in Northern New York near the Canadian border,right near the Saint Lawrence river which makes the borderline. Thanks very much Frank and all who have been so helpful taking time for me. But,doesnt 17 degrees seem to far advanced for the timing?

Mark,
What does the Jaguar factory decal under the hood of your car say about the timing? Attached is a picture of the decal from my US market 1986 XJ6 parts car showing that 17 degrees BTDC is correct for that car.

Paul

Paul,thank you so much,no wonder the engine is not running smooth.I will unhook the vacuum line to the distributor, and use my strobe light to achieve 17 degrees btdc. The wire going to the gas gauge sensor on the water rail shows only around 5 volts,the wire is green. Does this sound correct? with this single tab wire hooked up the gauge does appear to work.
thanks again, Mark

Mark,
Set the timing for what the decal on your car says, not necessarily what the picture of the decal from my 1986 XJ6 said. Emissions equipment and setup varied between markets based on country requirement. I have no idea what market your car was sold to or what has been done to it over the years. Setting the timing to the factory spec as detailed on the decal under the bonnet (hood) is a good place to start.
No, that is not correct. There is no gas gauge sensor on the water rail, they are in the fuel tanks. Do you have the owners manuals for your car? They explain many important things, including where the gas gauge sensors are.

Paul

boy do i feel stupid now. I typed gas gauge ,but I meant water temp sensor on the water rail,and water temp gauge with the single tab connection green wire. sorry, mark

The green wire shows only 5 volts going to the sensor on the water rail. Mark

Mark,
I have no idea what voltage should be going to the coolant temperature sensor on the water rail, but suspect that it should read 12VDC nominally. What does the coolant temperature gauge read when the engine is warmed up? I like to confirm that the coolant temperature gauge is reading properly with an infrared heat gun aimed at the coolant rail and coolant hoses and when warmed up that the auxiliary cooling fan comes on around 100C. I sold both of my XJ6 and no longer have one to test this on.
The coolant temperature sensor is likely a variable resistor that changes resistance when coolant rail temperatures change, so depending on how you take the readings it will show different voltages while the engine temperatures change.

Paul

More likely 5V. Most of that era’s EFI systems worked on a nominal 5V to all sensors.

Yes 5v is the correct signal for most ECU controls.

Kirby, Robin,
It is a little confusing trying to follow Mark’s posts, but I believe that he was asking about voltages on the Green-Blue wire going to the coolant temperature sensor for the gauge on the dash and not the EFI coolant sensor. He originally said fuel gauge sensor on the water rail but that was a mistake. I am pretty sure he was testing the Green-Blue wire for the coolant temperature gauge, but I could be wrong about that.

Paul

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It’s all about the market difference in vacuum source/control, Mark…:slight_smile:

Setting the advance with vacuum disconnected; the advance is purely centrifugal - the distributor is positioned to give this advance as a starting point. The ‘European’ vacuum set-up is ‘advance’, always added to the centrifugal - and sourced from manifold. Manifold vacuum, some 18" Hg, generally gives an advance of some 10 degrees when connected. The ‘US’ vacuum is ‘ported’, sourced from the carb/throttle - and is 0 with the throttle closed in idle.

The main point is that the engines’ advance requirements are constant; a built in characteristics of engine construction - not altered by advance settings. Difference in initial settings just reflects that different markets has different priorities for engine performance - and may also relate to difference is distributor advance curves. Relative merits may be argued endlessly…:slight_smile:

In short; advance should be set to specs related to model and market. Though some experiments with advance is fair enough considering doubts on provenance and engine state…

But you must check vacuum at the distributor vacuum hose - verifying if to have manifold or ported input. Setting 17 deg advance if manifold vacuum is used is plaint wrong…

Frank
xj6 85 Sov Europe (UK/NZ)
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Perhaps we need to differentiate between sensor (to ECU) as against sender to dash guage.

Excerpt from this:

Identification of sensors on the water rail
On the fuel injected 6-cylinder cars, here’s what the different sensors are and what they do, starting from the front position. First is the Thermotime Switch. This is a heated switch. It controls the cold start injector. This switch operates only when the starter is engaged and only when the engine is cold. Next is the sending unit for the dashboard mounted temperature gauge. Next is the fuel injection coolant temp sensor, which sends a signal to the boot-mounted ECU (Electronic Control Unit). This sensor is an important part of the fuel metering system. Rearmost is the temperature switch for the air injection pump and the canister purge system. On some non-North American and/or SeriesII cars this sender is replaced by a vacuum switch for the EGR-equipped cars.

Cheers
DD

Exactly, Paul

Cheers
DD

So I am not annoying anyone so called, trying to follow my posts,With the, in my case all green wire, this concerns the dash gauge. and it does show 5.2 volts cold . The all green wire goes to the one flat male connector on the water rail.Sure hope this is clear enough now.
All green ,not green_blue Mark

Mark,

You are not being annoying. We are just trying to understand your posts and help.:slightly_smiling_face:
Attached is a picture of the engine in my former 1984 XJ6 Vanden Plas. The coolant temperature sensor on the coolant rail that provides a variable voltage based on coolant temperature to the dash gauge circled in red.

The Series III XJ6s all had a Green wire with a Blue tracer strip in it going to this sensor when it left the factory. I suppose that someone working on your car could have changed out the original wire with an all Green one if they replaced that wire. Alternatively, the heat from years of use could have discolored the wire.

Paul

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thanks, Please tell me what is the function of the first sensor closest to the bulkhead,seems it is quite controversial. I have one here in this car,and if it has to do with an air pump, I dont see an air pump on Ruby Thank you very much , Mark

Not so much controversial as not fully understood. It is mentioned in this thread and many others in the past.

Your air pump may have been removed; very common practice. If your car never had an air pump please send a pic of the switch and details of the car, year and original market specifically

Cheers
DD