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On a car with carbs as opposed to fuel injection, I would suggest that your figures sound about right. I would get about 10mpg on my XJ12 (with injection) around town, 17mpg on long-distance runs. If you figure the difference for the larger, heavier XJ, offset by the benefits of fuel injection, then you would appear to be about normal.
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by junior: hi all,
hm.
still: my figures don't sound right.
it's not really a matter of money, it's more the "is-this-normal ?" kind a thing. with some 250 miles average driving/month the extra cost amounts to nothing substantial -at least not for a XKE-driver
i'm just wondering if my carbs are tuned correctly.
thanks, though.
junior<hr></blockquote>
Pull one each spark plug that is fed from each of the four carbs and see if the plugs look ok. (Black soot means too rich and thus buring (wasting) gas. They should be a nice even brownish color. Just something you can check easily.
Check the carb needle to see if it rubs the side of the jet. I had a few SU's on Triumphs that got gradually richer and richer because the jet was not centered in the lower gland nut and wear enlarged the jet and wore thew needle shaft.
Another thought is the condition of the spring and/or dirt in the inside of the carb domes. I found that the carb piston would stick inside the dome. Pul the dome and look at the deposits on the inside. I used to use carb cleaner to clean the inside of the dome and the piston lands to remove dirt and deposits.
Finally, check the carb float for evidence of liquid in the float that will allow the fuel level in the carb to be higher than it should be.
Any and all of these things will cause a slight increase in richness that will not cause black smoke, but will raise heck with your fuel economy.
I forgot to mention on other thing. The damper (the little shock absorber connected to the nut on top of the Carb dome) is supposed to have Castrol fork oil 20 weight (for motorcycle forks). I had a TR3 that had 20-50 weight oil instead. Accelleration was slow and rich decel because the damper was slowing the carb response when the oil was cold. Use a light weight motor oil if the fork oil is not available. A simple way to check this is lift the piston with the engine off. A lot of resistance may be due to the wrong viscosity oil in the carb piston damper.
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by junior: guys,
thanks for your sound advice. i'll be looking into it and keep you posted.
michael: dead on. i can hardly move the dampers when cold. i filled in 20W50 ...
you reckon that'd make such a difference?
junior<hr></blockquote>
Too heavy an oil in the damper can make a big differnce. YOu can actually buy oil made just for the dampers. I know that here in the states, XKs Unlimited sells it. It is part number: 03-BDR125 and is called "Genuine Damper Oil" There phone numbber here in US is: Or you can go to their web site: (805)544-7864
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by junior: basil,
thanks. help appreciated.
i guess i get similar stuff over here.
question: how do i get rid of the 20W50 which is already in?
junior<hr></blockquote>
Put some absorbant material on the end of a Phillips screw driver sna d carefully dip it into the damper wells to soak up the existing oil (use needle nose or tweezers to pull out the material if it gets jammed in there. Old cotton T-****s torn into pieces would work fine.
Junior:
Try auto trans fluid in cool weather, put 200,000
miles in a GT6, 150,000 on a XJ6 ser1 with the fluid, no problems at all as long as tuned proper.
But. the way I drive who cares about fuel mileage as long as the little school boy gets beat by the grey hair.
Larry
I used to have a S3 V12 OTS... I remember that if I behaved myself on the highway (Yeah, right.. more like the one time I was stuck behind an Illinois state trooper) that it got well into the teens.. 15ish on the highway.
City driving won't ever do much over 12mpg tho. I think you need to do the usual adjustments.
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by junior: hi all,
i've just got back to berlin from a 4 day, 1000 miles stint to
munich and salzburg. perfect weather, empty freeways, car ran
absolutely wonderfull. and, check this out: 17 mpg (US)
junior<hr></blockquote>
Wow, that is an impressive improvement! I know before you had said that changing the ignition helped some, but did you do anything else to account for the dramatic improvement?
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