| Author |
Message |
    
james woo
Frequent User
Username: james
Post Number: 22
Registered: 7-2003
| | Posted on Friday, 26 September, 2003 - 11:34: |    |
Hi Guys:
I understand Shadow I's average fuel consumption is about 15 miles per gallon, I have done just over 200 miles on my Shadow I since I got it, and the fuel consumption works out to be about 8 miles per gallon, which is quite a bit higher than the average, I do a balance mix of city and highway driving, and I am always easy on the accelerator, I am puzzled on how my Shadow use nearly twice as much fuel as the average consumption, is there something wrong with my car?
A friend of mine suggest that I should give the car a tune up, do you think this could be the problem?
Would you recommend using an fuel additive that are design to reduce fuel consumption, if so what product would you recommend.
Any suggestion is greatly appreciated.
Best Regards
James |
William H. Trovinger II
Frequent User
Username: bill_trovinger
Post Number: 29
Registered: 8-2003
| | Posted on Friday, 26 September, 2003 - 13:57: | |
James;
Besides engine performance (tune-up) other areas to look at are carburetors, tyre pressure, fuel octane, emission systems. I will tell you that my '76 SS is only getting about 9 mpg average around town driving and 13 on highway, when I got it the numbers where 7 and 10. Besides tune-up had carburetors rebuilt and we disconnected pollution pump. I do not know if you have that pump on yours but here once a car receives "collectors plates" it is exempt from emission standards. I would be very leery of putting any additive into any car. They all seem to remind me of the "Snake Oil Salesmen" in the old western movies. I would think that the additives could destroy gaskets and other internal components, costing you a lot more then the extra bit of fuel you are using.
Regards,
Bill
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james woo
Frequent User
Username: james
Post Number: 23
Registered: 7-2003
| | Posted on Friday, 26 September, 2003 - 16:12: | |
also, when RR say the fuel consumption is 15 miles per gallon, is it per UK gallon, or US gallon, I notice UK gallon is different to US Gallon
Regards
James |
james woo
Frequent User
Username: james
Post Number: 24
Registered: 7-2003
| | Posted on Friday, 26 September, 2003 - 16:17: | |
Thanks William,
thanks for the good advice, will try these thing and let you know the outcome.
Regards
James |
Bill Coburn
Prolific User
Username: bill_coburn
Post Number: 47
Registered: 4-2003
| | Posted on Friday, 26 September, 2003 - 17:21: | |
Check that you have a clean air filter, that the autochoke is coming off quickly, fit new spark plugs and have High tension leads checked on a 'scope. Ensure carbies are not leaking at the bottom which means diaphragms are punctured, in any case fit new main jets and needles. While you are at it replace needle valves in float chambers and re-set levels. Of course you have kept the pistons and dampers in the carburetters clean and the dampers filled with engine oil! |
Jon Rothwell
Unregistered guest
Posted From: 203.10.1.25
| | Posted on Friday, 26 September, 2003 - 22:18: | |
Not all cars of the same make will have the same fuel consumption. For example an Australian compliance EFI V12 Jag with a low compression engine and full anti pollution gear will give woefull milage compared to a non pollution higher compression EFI English V12.
Have a look at the compression ratio and anti pollution gear fitted to your car, then tune it as recommended by the factory. Assuming that the car is tuned correctly and all systems are in good condition then that is about the best you will get.
There are ways to improve fuel consumption on any car, for example, some years ago I won a bet by tuning an older carby XJ Jag to give well over 25MPG when the factory mileage was 13MPG, and have often got 5.8 high compression 10:1 Ford V8's to give 25MPG.
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David Gore
Moderator
Username: david_gore
Post Number: 110
Registered: 4-2003
| | Posted on Friday, 26 September, 2003 - 23:05: | |
James,
The British magazine "Autocar" has tested several Shadows and Corniches over the years and the fuel consumption figures are as below [figures are in Imperial gallons not US gallons]:
Shadow I [6.23 litre 4 speed auto] Test No. 2125 [30th March 1967]:
Fast Continental Touring: 11mpg [25.7L/100km]
Gentle Touring: 15mpg [21.6L/100km]
Overall on test: 12.2mpg [23.2L/100km]
Shadow I [6.75 litre 3 speed auto] 1st May 1976]:
Overall fuel consumption: 13.6mpg [20.8L/100km]
Hard driving: 12.2mpg
Average driving: 15mpg
Gentle driving: 17.7mpg
1974 Corniche [6.75 litre 3 speed auto] no test date:
Overall on test: 11.9mpg [23.7l/100km]
Claimed typical: 12.5mpg [22.6l/100km]
Fuel consumption at constant speed
30mph: 19.1mpg
40mph: 18.7mpg
50mph: 18.1mpg
60mph: 17.2mpg
70mph: 15.8mpg
80mph: 14.1mpg
90mph: 12.3mpg
Oil Consumption: 500 miles per pint
Top speed recorded: 122mph [196kph] @ 4660rpm]
Standing Quarter Mile: 17.1sec terminal speed 81mph
Standing Kilometre: 31.8sec terminal speed 101mph
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james woo
Frequent User
Username: james
Post Number: 25
Registered: 7-2003
| | Posted on Saturday, 27 September, 2003 - 08:12: | |
thankyou gentlemens!
Thankyou for pointing me to the right direction and for providing me with all the useful info.
The only thing stopping me from driving the Shadow everyday is the cost of the fuel, if I can get the average consumption to 13mpg I will be happy, and will be able to enjoy the car everyday!
Thanks again
Regards
James |
Robert Chapman
Yet to post message
Username: shadow
Post Number: 2
Registered: 5-2003
| | Posted on Saturday, 27 September, 2003 - 22:50: | |
James;
It sounds to me that the fuel weakening device on your car is not working,this is a very common cause of high fuel consumption with Shadows.This device leans off the fuel mixture at light throttle/cruise operation.Without this working your mixture will be 4to5 % CO.With it working it will be .5% CO .You can test if it is working your self by putting your finger over the inlet filter{on left hand inner guard} whilst the engine is idling at operating temp,if it is working the engine will stop.You will need to take your car to your local dyno tuning centre to have it properly checked and adjusted. |
james woo
Frequent User
Username: james
Post Number: 26
Registered: 7-2003
| | Posted on Sunday, 28 September, 2003 - 12:03: | |
Thanks Robert! Will check this.
Also bill, how do I tell if the auto-choke off, do I tell by the noise, how long is the auto-choke suppose to stays on? Thanks again gentlemens!
Regards
James |
Bill Coburn
Prolific User
Username: bill_coburn
Post Number: 48
Registered: 4-2003
| | Posted on Sunday, 28 September, 2003 - 18:09: | |
James
The choking on these cars was done on the main air intake on top of the engine. If you take off the flexible trunking from the top end you will see the very large butterfly valve that is the choke. First use plenty of light oil on the axle of the valve to ensure that it is quite free. Note also the external lever at the side that operates your fast idle cam. This lever is parallel with the butterfly valve so that when it is pointing along the axis of the air intake the valve is fully open. Make sure that the fast idle cam is also lubricated and drops down when it is released. As to its operation when you set the choke by depressing the accelerator when the engine is cold, the choke lever should be pointing down showing that the butterfly valve is shut.Start the engine and let it warm up. The lever should slowly rise opening the choke. Apart from sticking the other common problem is the intake choke stove pipe will corrode and break off at the manifold drawing in cold air and allowing the choke to stay on. |
Serge PONTES
New User
Username: serrgio
Post Number: 4
Registered: 1-2004
| | Posted on Saturday, 28 February, 2004 - 21:01: | |
Hi Guys,
With my 1976 Shadow 1 (motor6,7l), living in Paris, and driving most of time in traffic jam, I need 25l/100km (but since I have the car, and after 500km, I didn't need to add oil; so engine seems to be in good condition). So, don't be affraid about consumation !!!
by
seRRgio |
David Gore
Moderator
Username: david_gore
Post Number: 209
Registered: 4-2003
| | Posted on Saturday, 28 February, 2004 - 21:55: | |
Hi SeRRgio,
Just a cautionary comment - it is not unusual for ordinary oil consumption to be masked by condensate build-up in the sump when a car is driven under similar conditions to your description. If the car is then taken for a long-distance high speed journey; this condensate evaporates and the oil level drops significantly reflecting the oil consumed during city use.
As stated many times in this and other forums, the V8 engine in good condition will burn oil at a controlled rate up to a litre per 1000 miles. The most reliable assessment of engine condition is a compression and vacuum test and not oil consumption. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 129
Registered: 4-2003
| | Posted on Saturday, 28 February, 2004 - 23:03: | |
Further to David's comment, in most cases oil consumption in these V8 motors is almost exclusively due to the rubbish pre-war valve stem "seal" (waxed rope pellet) they used. Those do not really control the oil and are very hit and miss. Updating to a set of later Silver Spirit types will almost eliminate oil consumption on most of these motors and ensure that a really controlled lubrication of the valve stems is achieved. If you have the heads off for any reason it is worth considering an update. You can buy aftermarket equivalents for around A$35 for 16 seals plus A$60 for the cutting tool and get a brilliant result. I put a set on my R-Type inlet valves (similar, but the stem is of a smaller diameter than the V8s), over twelve years ago, and the oil level doesn't even drop 1mm between changes. Also, the oil stays clean which must be a good sign. I have fitted them to several other Crewe cars for friends and the results are the same. If anything, the valve stem wear is reduced with the new seals. |