what is a good mileage for a Silver Shadow? I get 6 MPG

gdv01 · New Member Joined: 05 May 2009 Posts: 3

I am getting about 160 miles per tank. that is about 6 miles per gallon. Too high, I think. I noticed a weak spark, so I installed electronic ignition, and found small enhancement, from 160 miles per tank to 170 miles per tank.

Any ideas? the car starts well in the mornings and does not hesitate running, I believe it is properly carburated, but I have reason to believe that in 10 years nobody has opened the carbs or even adjusted them.

advise?
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Mexican 1972 Silver Shadow

SiroccoRacing · Posted: Wed May 06, 2009 8:47 pm Post subject:

I too had a '72 Shadow a few years ago. She was good for about 7 miles a gallon. Cruising at 80MPH or 10MPH around town=7 MPG. You've got 3 tons, 6.7 Liters and just enough HP to drive the AC and motor nicely.

If she hasn't been tuned in 10 years, it would be a good idea to do it. The electronic ignition is a good idea. Enjoy her!

wookieecantina · Member Joined: 06 Jan 2009 Posts: 22

I have a 1976 Shadow with stock electronic ignition, it seems to be average approx. 11 miles per gallon, slightly better on the highway, but we don't drive excessively.
I did recently change the plug wires to a heavier silicone wire and converted the spark plugs to the Pulstar Pulse Plug, part number Be1. I e-mailed the company regarding any possible issues with these new style plugs being used in an RR and they were quite confident with their product as several other RR owners have experienced success with them.
While some may feel they're a bit costly and not worth the price of $24.99 per plug, I just had to try them.
I haven't checked my mileage after installing them, but I will honestly say, the vehicle runs incredibly smooth. I also balanced both carbs with pot-mount gauges with Sherbourne Mews.
http://www.sherbournemews.com
The Shadow passed smog with flying colors three weeks ago, in fact, the smog station owner was very impressed at how clean the engine was running.
You can read about the plugs on their web site:
http://www.pulstar.com/
Overall, I'm very pleased! Our Shadow just purrs, starts easier, runs smoother and the acceleration does feel a bit more responsive.
Some may not recommend these new style plugs, but I've since installed them my daily driver (2005 XB) and can actually feel a bit more power Very Happy

If you try them, please let me know what you think.
OH!!!! Be careful installing them as I cracked one by accident (front left) while installing in the Shadow and you can only by them in pairs. Well at least I have a spare.
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Dale

AlanD · Posted: Sun May 10, 2009 4:31 am Post subject: Fuel consumption.

I get around 14 mpg (UK) if I don't thrash it, on mixed type driving. I suggest your car has been serviced by someone with a less than satisfactory knowledge of the car. My first purchase had the ignition timing retarded by 20 - yes, twenty, degrees. The result of correcting that was sensational. As someone has suggested, get the ignition and carburration correct, then see what happens. 6 mpg is appalling.

Regards from Alan D.

mattjdduncan · Posted: Fri Oct 23, 2009 11:07 am Post subject:

always worth giving it a little tune up. set the timing then the mixture then the idle speed.

May help.

Matt.
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Skype Matthew_3

Eddie3000 · New Member Joined: 01 Mar 2010 Posts: 4

I have a shadow II and will get 275+ miles out of a tank full so there is something very wrong.
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Eddie3000

Stirling · Posted: Mon Mar 01, 2010 8:31 pm Post subject: Re: Mileage Issues! Ouch!

wookieecantina · Member Joined: 06 Jan 2009 Posts: 22

Thanks for writing to remind me about the spark plug posting!
Well, I changed my old plugs approx 500 miles ago and did switch to the Pulstar #BE1 plug.
Definitely not cheap at approx. $24.00 per plug, ouch! With gas costing over $3.00 per gallon, I felt it was worth a try so I bit the bullet and purchased.
I e-mailed Pulstar prior to purchase and they responded immediately with the data I requested and they explained about the plug temperatures and how the Pulstar plugs did in fact tend to run cooler, yet disperse a substantially stronger spark. I was worried about burning a hole in a piston or some such event.
Overall, I'm very pleased with their performance. The Shadow appears to have slightly more power while accelerating and the fuel mileage seems to have improved. Not much, but I guess .65 miles per gallon increase is quite substantial, especially when you're talking about a motorcar that tends to drink petrol like an ice cold Coca Cola a hot day.
The car still has a tiny bit of rough idle during warm up, but once proper heat has been established, she smooths out wonderfully.
I guess time and mileage will be the true test, but I'm pleased!
I also changed the oil to a Royal Purple Max Cycle synthetic, so between these changes, hopefully the old girl will keep running for many years to come.
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Dale

Stirling · Posted: Mon Mar 01, 2010 9:51 pm Post subject:

Thanks for the update Dale. I was interested to hear the results of your usage as I had a similar experience a few years back with another product that was a premium priced alternative.

When I began putting Amsoil into my BMW E34 M5 I was startled at the change: ran cooler, smoother and faster. So I wasn't that skeptical when you mentioned these spark plugs.
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Stirling

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