what is a good mileage for a Silver Shadow? I get 6 MPG - Rolls-Royce and Bentley Forums
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 17 (permalink) Old 05-05-2009, 11:24 PM Thread Starter
New Member
 
Join Date: May 2009
Posts: 3
what is a good mileage for a Silver Shadow? I get 6 MPG

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?

Mexican 1972 Silver Shadow
gdv01 is offline  
Sponsored Links
Advertisement
 
post #2 of 17 (permalink) Old 05-06-2009, 09:47 PM
New Member
 
Join Date: Mar 2009
Location: Left Coast
Posts: 11
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!
SiroccoRacing is offline  
post #3 of 17 (permalink) Old 05-07-2009, 11:49 PM
Member
 
wookieecantina's Avatar
 
Join Date: Jan 2009
Posts: 22
Mileage Issues! Ouch!

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
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.

Dale
wookieecantina is offline  
 
post #4 of 17 (permalink) Old 05-10-2009, 05:31 AM
New Member
 
Join Date: Jan 2007
Location: Somerset, England.
Posts: 6
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.
AlanD is offline  
post #5 of 17 (permalink) Old 10-23-2009, 12:07 PM
Phantom
 
Join Date: Oct 2009
Location: Kingston Upon Thames
Posts: 78
always worth giving it a little tune up. set the timing then the mixture then the idle speed.

May help.

Matt.

matt@introcar.co.uk

www.introcar.co.uk

Tel +44 (0)20 8546 2027
Skype Matthew_3
mattjdduncan is offline  
post #6 of 17 (permalink) Old 03-01-2010, 07:21 PM
New Member
 
Join Date: 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.

Eddie3000
Eddie3000 is offline  
post #7 of 17 (permalink) Old 03-01-2010, 08:31 PM
Super Moderator
 
Join Date: Jan 2007
Location: Ontario, Canada
Posts: 390
Re: Mileage Issues! Ouch!

Quote:
Originally Posted by wookieecantina
...
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
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.
Wookie I'm curious to hear more about these plugs. Are you still using them? Did you ever measure if they're giving you more mpg?
Stirling is offline  
post #8 of 17 (permalink) Old 03-01-2010, 09:19 PM
Member
 
wookieecantina's Avatar
 
Join Date: Jan 2009
Posts: 22
Pulstar Plug Review

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.

Dale
wookieecantina is offline  
post #9 of 17 (permalink) Old 03-01-2010, 09:51 PM
Super Moderator
 
Join Date: Jan 2007
Location: Ontario, Canada
Posts: 390
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.
Stirling is offline  
post #10 of 17 (permalink) Old 02-28-2011, 05:28 PM
New Member
 
Stumbler's Avatar
 
Join Date: Feb 2011
Location: London
Posts: 19
I have just bought a 76 Corniche, and although I haven't done many miles in it, I have kept a record of all petrol purchases and miles travelled.

Driving through 34 miles through London in clear traffic has resulted in 7.44mpg, and a 90 miles motorway trip gave me 13.45mpg.

According to the poor service record I received when I bought the car, the carbs had just been serviced and reset before I bought it. So the real issue will be tyre pressure. Since doing these trips I have measured tyre pressures and found I was running on 28 and 24 at the back, and 26 and 25psi in the front. I have since put nitrogen in the tyres, which will hopefully keep a stable pressure, and have pumped these up to 30psi at the front and 35 at the rear. I will post my new mpg when I have been able to repeat those same runs in the same conditions.

1976 Bentley 1A Corniche (Rolls Royce conversion)
CRH21998
Stumbler is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Rolls-Royce and Bentley Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

SEO by vBSEO 3.6.1