| Author | Message | |||
     Martin Taylor Experienced User Username: martin_taylor Post Number: 10 Registered: 11-2003 |
I have a shadow I that was knocking badly under hard acceleration, I traced the cause to a broken advance weight spring in the distributor. There were two springs, one thick wire and the other thin, I don't know if these were origonal, the thin one had lost it's tension. I have replaced both springs with a matched pair from a Rover distributor and the engine no longer knocks. I don't know if it is advancing correctly, so far all the figures I can find to check it are way outside the range of the distributor which according to the stamp on the advance mechanism stop all further advance at 14 degrees. Can anyone give me the correct advance curve as the RPM increases. I expect I would be able to adjust spring tension until in the ball park with a tach and strobe. The car is SRH13066 and is ex UK York Motors Demonstrator. Thanks for any information. | |||
| David Gore Moderator Username: david_gore Post Number: 214 Registered: 4-2003 |
Martin, have attached non-smog distributor advance curves for centrifugal and vacuun actuation. The data is best seen by opening the document in Microsoft Word and adjusting the view enlargement to 150/200%. Viewing at 100% gives a distorted image. Opening with "Wordpad" gives a low resolution out-of-focus image.
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| Martin Taylor Frequent User Username: martin_taylor Post Number: 11 Registered: 11-2003 |
Thanks David, that is exactly what I needed. | |||
| Robert Chapman Prolific User Username: shadow Post Number: 38 Registered: 5-2003 |
Hi Martin , Remember that distributor speed and degrees of advance are half of those quoted for the engine at the crank pulley. | |||
| Martin Taylor Frequent User Username: martin_taylor Post Number: 13 Registered: 11-2003 |
Thanks Robert, I will admit to several seconds of confusion until I worked that one out. I set it up as best I could last night, after removing and refitting the contact breaker housing no less than four times I can see where a test bench would be helpful. I checked for no advance at 500 RPM and maximum advance at 3000 RPM (18 degrees) to get these values I used a small spring from a Sony VCR and a large spring from a Rover distributor. The car has a LOT more power and is a totally different animal to drive. I had the manual on CD but the above graph must be from a later publication as it was not present in my version. The distributor was stamped at 18 degrees, not 14 as previously stated. Thanks for all the help, now to fix the rest of the car....... | |||
| Kevin D Ritter New User Username: 1025username Post Number: 2 Registered: 4-2013 |
Giles- I have 1974 Rolls Royce Silver Shadow Right Hand Drive (9 to 1 compression ratio ) with a Lucas Distributor 41380 with no vacuum advance. I am basically looking for the advance curve data points, i.e. would like to know the amount of crank advance at 1200 and 1500 cranks RPMs. Thanks. | |||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 854 Registered: 9-2004 |
What you need then is the dwell set to 26-28 to start with. Timing to start 0/500 rpm intermediate 5/900 rpm intermediate 20-24/2000 rpm ends 34-38/3000 rpm Road test and back off if pinging or pinking is present. If you need vacuum adv figures etc I have them. | |||
| David Gore Moderator Username: david_gore Post Number: 1283 Registered: 4-2003 |
The original Shadow workshop manual included distributor advance curves for engine speed and vacuum - I apologise for the poor quality scan as it was not done be me.
See post above dated 29th February 2004 for information re viewing. |
advance