[xj] old problems solved and now still pulling my hair out (Update)

Hi All,

Have been away on holiday for the last couple of weeks and returned
yesterday and have carried out work today therefore an update on
the latest situation:
My parts for the HIF7 carbs arrived whilst I was away. I have now
fitted new needles, guides and floats and setup as su carb book. I
have now no more overflow leaks out of the carbs however, the AED
continues to leak. I have now removed this and joined the carbs
with straight through hose connection and blanked off the vacuum
intake. The car starts and runs sort of okay however I need to tune
the carbs to get them into any sort of tune as I need to take the
car to get the valve adjustment carried out by a specialist. I have
in my possession a gunsons carb balancer, colortune and a
gastester, can anyone suggest tips and/or guidelines on the best
course of action in order to get the carbs in a reasonably tuned
state either using these instruments or not prior to the valve
adjustment. Any advice gratefully received.

Thanks & Regards,

Ken–
1978 xj6 series II 4.2 LHD
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In reply to a message from xebec sent Mon 12 May 2008:

Ken:

This is a generic answer to multiple carburator balancing.

  1. Look down the bore and see if the throttle plate closes
    completely off throttle. If not, adjust with the linklage
    disconnected.

  2. Adjust the linkage so that the plates commnce to open at
    precisely the right time.

  3. Verify that both throttle plates are fully opened when the foot
    pedal is on the floor.

This gets most in synch.

The next aspect id mixture balance. I found that a vacum guage for
each carb helped me balance the mixture. But,that doesn’t assure
the rich v lean. An ear or two plus some seat of the pants was the
way we got that close enough. Spark plug exqm after a run and a
clean shut down is a better way. I hqav never had the benefit of a
gas analyzer. I am not too confident with a Color Tune, as they are
pretty much limited to idle. I don’t think they will take a lot of
throttle.

There is software/hardwre tat will read exhaust from an O2
sensor.

Good luck !!!

Carl–
The original message included these comments:

My parts for the HIF7 carbs arrived whilst I was away. I have now
fitted new needles, guides and floats and setup as su carb book. I
have now no more overflow leaks out of the carbs however, the AED
continues to leak. I have now removed this and joined the carbs
with straight through hose connection and blanked off the vacuum
intake. The car starts and runs sort of okay however I need to tune
the carbs to get them into any sort of tune as I need to take the
car to get the valve adjustment carried out by a specialist. I have
in my possession a gunsons carb balancer, colortune and a
gastester, can anyone suggest tips and/or guidelines on the best
course of action in order to get the carbs in a reasonably tuned


Carl Hutchins
Walnut Creek, California, United States
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===================================================
The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from xebec sent Mon 12 May 2008:

Hi Ken
I hope you are successful re-building the HIF carbs. I went
through the whole process, including re-building the AED
(and some extra ones that came my way) in an attempt to cure
my XJC of a reluctance to start when hot. In the end I
changed the whole set-up to the earlier configuration of
HD8’s with the thermo choke - a decision I’ve never
regretted, but that’s another story!
When I was tuning the HIF’s I used a gas analyser as, IMHO,
that is the most accurate way to set the mixture. Mr Haynes
says 3% CO maximum is the setting for carburretors and I
found that was perfectly OK.
Good luck and cheers–
The original message included these comments:

in my possession a gunsons carb balancer, colortune and a
gastester, can anyone suggest tips and/or guidelines on the best
course of action in order to get the carbs in a reasonably tuned
state either using these instruments or not prior to the valve
adjustment. Any advice gratefully received.


Barry Woolcott NZ 1977 4.2XJC
Waikanae, New Zealand
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from Barry Woolcott sent Tue 13 May 2008:

Hi Barry,

Thanks for the useful information, much appreciated. I note that
you have rebuilt the AED and therefore could you offer any advice
on the setting for the grub screws for the adjusting Needle and
Valve. I am attempting to rebuild mine as I have the overhaul kit
however, I had to remove the grub screws. I am not sure of how far
they need to be screwed in and how to adjust.
Your experience in this situation would be gratefully received.
Thanks & Regards,

Ken–
The original message included these comments:

I hope you are successful re-building the HIF carbs. I went
through the whole process, including re-building the AED
(and some extra ones that came my way) in an attempt to cure
my XJC of a reluctance to start when hot. In the end I


1978 xj6 series II 4.2 LHD
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

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The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from xebec sent Thu 15 May 2008:

Hi Ken
Happy to send you the info on setting the adjustments on the
AED. However, I’ll have to dig around a bit - will scan the
pages and e-mail them, but it might take me a day or two.
Will be in touch
Cheers–
The original message included these comments:

you have rebuilt the AED and therefore could you offer any advice
on the setting for the grub screws for the adjusting Needle and
Valve. I am attempting to rebuild mine as I have the overhaul kit
however, I had to remove the grub screws. I am not sure of how far
they need to be screwed in and how to adjust.


Barry Woolcott NZ 1977 4.2XJC
Waikanae, New Zealand
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
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In reply to a message from xebec sent Thu 15 May 2008:

Ken

the clearances on the two grub screws are temperature dependant as
follows:

Main jet:
10�C .045’’
15.5�C .038’’
21�C .030’’
26.5�C .023’’

Jet needle lift adjuster:
10�c .050’’
15.5�C .045’’
21�C .031’’
26.5�C .022’’

This assumes you’ve used the standard thickness gaskets and the
ferrule the screws are mounted in hasn’t moved in the bakelite
housing.

There’s a picture of a tool I devised for setting this here:
http://www.jag-lovers.org/snaps/snap_view.php3?id=1136490530

The figures above are taken from SU service sheet AKD 7222A which
is one of four bulletins that describe the set up of these often
misunderstood devices.

Setting the grub screws is easier (I found) than setting the needle
height, this one moves in 16ths of a turn and can only be set with
the engine cold which means several attempts with lengthy gaps in
between.

Satisfying when done however.–
The original message included these comments:

you have rebuilt the AED and therefore could you offer any advice
on the setting for the grub screws for the adjusting Needle and
Valve. I am attempting to rebuild mine as I have the overhaul kit
however, I had to remove the grub screws. I am not sure of how far
they need to be screwed in and how to adjust.


al mclean '93 XJS 4.0 - '84 4.2 Daimler - '84 DD6
Telford, United Kingdom
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The archives and FAQ will answer many queries on the XJ series…
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