First, thanks for the timing advice. Jacked it up, set the timing
statically. I’m going to put a pointer on the side of the timing
cover. Next question: I’m getting more and more disenchanted with
the Jag manual. I’ve got the car on the road (69 OTS) and it starts
fine, runs great to 4,000 in first, 3500 in second, 3000 in third.
Doesn’t want to run at all above that. New plugs, wires, points set,
timed, carbs taken down and set. 150 lbs across the head. It’s
running lean on all six, especially the rear three. Old plugs were
snow white, and replacing them didn’t change anything. The manual
gives instructions on rebuilding the fuel pump, but no specs on
volume, that I can find. And as to the cause of poor high speed
running, it gives reasons for hard starting, and then says that poor
acceleration and poor high speed performance will be caused by the
same problems. And it seems there are no adjustments on the carbs.
With SUs or Webers, I’d know what to do. What do I do with
Strombergs? Run with the choke on? Taper the needles? And can anyone
tell me what the pump should produce per minute? My thanks.–
IanCameron
Brentwood Bay, B.C., Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Ian,
First, try to figure out what the problem really is. If you
suspect it’s running lean, then run it up to where it starts
misbehaving, and apply the choke. If it improves, then you know
you have a carb problem, not a fuel supply problem. I would think
it far more likely your distributor advance is not working
properly, as that’s about the range where you’ll really start to
see it. Get a digital advance timing light, and run the engine in
neutral up to about 3500 RPM, checking the timing at the specific
RPMs listed in the service manual for your distributor. I suspect
you’ll find one of the weights it stuck and you’re not getting full
advance.–
Ray Livingston - '64 OTS Santa Cruz, CA
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Ray Livingston sent Fri 16 Jun 2006:
One other thing. These harmonic dampers with the timing
marks are 40 years old. It is entirely possible that the two
parts ot it have slipped as the rubber between has aged and
hardened. This could cause the timing to be off without you
knowing it. I suggest you check the TDC position of the
piston against the timing mark.
In reply to a message from Ray Livingston sent Fri 16 Jun 2006:
Thanks for the suggestions: since testing the advance dynamically
means lying under the car with the engine running at 3500 RPM three
inches above my face, I’d really like to check the fuel pump first.
Is there no datum on how much the pump should produce per minute?
(I’ve tried applying choke at speed: no difference. But I’ll try
that again: maybe I didn’t give it long enough.)–
IanCameron
Brentwood Bay, B.C., Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Sorry: forgot to say that as the plugs are snow white, doesn’t that
indicate that the mix is lean? If the distributor advance weren’t
correct, one would expect the plugs to be fouled, or at least dark.
No?–
IanCameron
Brentwood Bay, B.C., Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Ian,
With unleaded gas, it’s not unusual for the plugs to appear
white. With a bad distributor advance, they’d only be fouled if
you ran long enough at high RPM, with the engine misfiring, for
them to get fouled. If pulling the choke didn’t improve the
situation, it’s not running lean.–
Ray Livingston - '64 OTS Santa Cruz, CA
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Ian,
Check the fuel pressure, as a drop in pressure at higher
revs will indicate a decrease in flow.
I have seen it somewhere in the archives on one of the lists
but if I remember correctly the flow is significant -
gallons per hour, but certainly as you probably are aware,
SU’s and Webers, and I asume Strombergs, are sensitive to
fuel pressure. Usually too much, more than 2 psi, rather
than not enough, causes problems.
You could check the flow by disconnecting the line to the
carbs and measuring the output over time. If it is fuel
delivery then it may be a filter issue rather than the pump.
Using the logic that the carbs worked with the jet setting
at one point, then there is something else that is the issue.
Regards
Keith–
The original message included these comments:
the Jag manual. I’ve got the car on the road (69 OTS) and it starts
fine, runs great to 4,000 in first, 3500 in second, 3000 in third.
Doesn’t want to run at all above that. New plugs, wires, points set,
snow white, and replacing them didn’t change anything. The manual
gives instructions on rebuilding the fuel pump, but no specs on
volume, that I can find. And as to the cause of poor high speed
–
Keith Bertenshaw
Rockaway, NJ, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Ian,
Take the fuel delivery hose of the carbs and aim in a can or
bucket. Have your assistant turn the ignition on.
It it comes out like a frat boy from UCAL @ Santa Budweiser you’re
ok.
If it come out like a 60 year old with a prostate problem, you have
issues.
We ain’t launching the space shuttle!
Just make sure your float level is OK on a ZX carb. Are the slides
rising when you give it some throttle?
D–
1969 BRG OTS
Skaneateles, NY, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from David Ahlers sent Fri 16 Jun 2006:
Fuel pressure should be 3.5 lbs. Too much and you flood/leak
everywhere. Too little, and at high rpm you run out of gas! I had a
fuel pump issue (too much pressure) so I purchased a fuel pressure
regulator (about $20.00), set it at 3.5 lbs and the Jag runs fine
now, and, no leaks.–
Jim Tison, '68 2+2,
Cumming, Georgia, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Hiya Ian,
Get a mirror and lay in under the pulley. Aim your timing
light into the mirror and move mirror, light, your head,
until you can see the marks in the reflection.–
The original message included these comments:
Thanks for the suggestions: since testing the advance dynamically
means lying under the car with the engine running at 3500 RPM three
inches above my face, I’d really like to check the fuel pump first.
–
Bent Bob
Fredericton, New Brunswick, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Are your needle and seat in the carb. working properly?
Are the floats adjusted properly?
Are your pistons in the carb. sticking?
Walter
69E ser.II--
The original message included these comments:
the Jag manual. I’ve got the car on the road (69 OTS) and it starts
fine, runs great to 4,000 in first, 3500 in second, 3000 in third.
Doesn’t want to run at all above that. New plugs, wires, points set,
–
Walter Schuster 78XJ6LFI Ser.II, 69Eser.II 2+2
Albuquerque/New Mexico, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from IanCameron sent Fri 16 Jun 2006:
Hello Ian,
The stock SU pump delivers 21 gal/hr, or around 45 oz/min. The
most efficient XK engine has a BSFC of 0.55 lbs/hp/hr, which means
the stock pump at full output could support a 230 net hp engine
(21x6 lbs/gal)/0.55. You generally want at least 20% headroom, so
the stock pump is near the limit on a 190 net hp engine. The
pressure should be limited to 2-3 psi. If you suspect poor fuel
delivery at high load, fit a pressure gauge and look for a pressure
drop at high speed.
The springs in the distributor are often worn, giving a false
advanced reading with a timing light at idle. You set it to 10 BTDC
with the light, but since the distributor is already advancing at
idle speed, your total timing is retarded. Put a few drops of oil
under the rotor and make sure that the rotor snaps back under
spring pressure when you turn it by hand. Then try setting the
timing statically or mark the damper or use an advance timing light
to check the timing at 3000 rpm, you should be in the mid 30’s BTDC.
In reply to a message from PS sent Sat 17 Jun 2006:
Well, the long-distance diagnosis contest is over, sort of, and the
winner is…………me. Hem, hem. Well, I’m not taking any credit at all,
given that I could drive the thing, and it still took me way too
long to be sure it was gas. But I became pretty sure, as I tried
different things. It would rev perfectly up to 4000 in first, but
wouldn’t hold it for more than 10 seconds or so before breaking down
badly. Had to be fuel starvation. I undid the fuel line between the
glass bowl and the carbs, turned the key, and pumped into a one
litre container. It took four minutes. “Well, hell,” I said. “That
can’t be right. No engine this big can live on 15 litres of gas an
hour. Jeez, I’d be getting 25 miles per gallon at 100 miles per
hour.” Took the fuel pump out, and what to my wondering eyes should
appear, but a brand new pointless S.U. AZX 1307. That can’t be the
problem. (But at that point I knew why I got such a deal when I
bought the car: the owner put in carb kits, new pump, and it still
wouldn’t go, and he was glad to get rid of it.) I pulled the line
from the fuel tank, put it into a container of gas, turned on the
pump. This time it pumped a litre in one minute. Four times as much.
60 litres an hour – 15 gallons. That‘s better. Pulled the lid off
the tank, and took out the filler pipe. Couldn’t blow through it.
The wonder is that the engine ran at all. Took it out, cleaned it,
removed a pile of grunge, put it all together, and it ran as a Jag
should. However, I took my wife out later for a drive, and it
started doing the same thing, but not as badly. My guess is that the
tank is full of crud, and the screen at the bottom of the pipe is
clogged. I’ll check tomorrow and let you know. And if that’s not the
case, then we’ll get on with the ignition system again.–
IanCameron
Brentwood Bay, B.C., Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–