|Posted on Friday, 18 December, 2015 - 06:04:
First, Happy Christmas to all readers,
The problem I am having with the 1982 RR is that on tickover it feels as if the engine is 'missing' slightly. If I go into Reverse it become more pronounced and in Drive the 'missing' becomes a judder. I have replaced the plugs, ignition leads, rotor arm and tried a different coil. Also replaced main fuel filter and the two small ones on the carbs. I would like to hear if anyone can give me some idea where to try next.
All the best for 2016, Clive
(Message approved by david_gore)
Post Number: 142
|Posted on Friday, 18 December, 2015 - 08:08:
Hello lungmuss - two thoughts - one is the carburettor dashpots, do they have sufficient oil? The other is the mixture weakener solenoid having failed?
Does she pick up without hesitation, and no missing on acceleration?
I have a similar problem on my '84 Spirit, spent ages balancing the carbs (raising and lowering the jets) but the 'problem' persists, very slight but still there!
If you find the solution don't forget to post it!
Post Number: 1856
|Posted on Friday, 18 December, 2015 - 08:18:
Hi Clive and welcome back,
Have you looked for "tracking" of the HT current on the distributor cap also for cracking in the cap? Have you tried a known good distributor cap?
When did you last clean the carburettors themselves? Could be a sticking inlet valve or the piston sticking due to varnish build-up on the bore of the carburettor body.
Post Number: 270
|Posted on Friday, 18 December, 2015 - 19:43:
Hi Clive, sounds like a misfire, becoming more pronounced under load. Have you tried disconnecting each plug at a time, to isolate the cylinder. Alternatively do you have a local garage with an" old fashioned" Crypton Engine analyser that could identify which cylinder is guilty under load.
Post Number: 59
|Posted on Friday, 18 December, 2015 - 20:46:
I second Daves comment , on my '83 mulsanne turbo I got through 2 dizzy caps, I got my replacments from halfords for rover v8 exact same cap 1/4 price ok
richard george yeaman
Post Number: 418
|Posted on Friday, 18 December, 2015 - 21:28:
Hi I am with David and Michael has to be the distributor cap or maybe the electronic ignition playing up.
Post Number: 1044
|Posted on Saturday, 19 December, 2015 - 03:15:
I suspect the electronic ignition module. However, given the distributor cap is relatively cheap to replace I would definitely try that first.
I've found in the past the best way to approach this problem is the way Clive has, by substituting parts one by one until the defective component is found. In my case replacing the condenser, on the older points system engine, provided an improvement but only when I replaced the coil was the fault finally cured. I realize Clive has already checked the coil on his car - two components left to substitute.
richard george yeaman
Post Number: 420
|Posted on Saturday, 19 December, 2015 - 07:19:
It would also have helped if when the plugs were changed they had been inspected for anything unusual such as soot, oil, or burnt out electrodes. When I changed the plugs on my Silver Shadow when it had a bout of irregular running I found that B4 was in a shocking state completely grown over like a blob of ash no one had changed it for years because it was difficult.
Post Number: 62
|Posted on Saturday, 19 December, 2015 - 07:58:
Clive, you said you "tried a different coil" Yes, but was it a new one or had it been tested on a coil tester to determine if in fact it was good? I agree with the previous posters that you should replace the cap also. A "judder" in my experience is usually a dead cylinder due to bad plug or lead, or cap that is tracking sometimes to another cylinder firing it at the wrong time. I don't mean any disrespect, but are you sure the plug leads are in the correct order too. Engine misses are almost always ignition related, fuel is usually lack of power.
|Posted on Saturday, 19 December, 2015 - 00:16:
Big Thanks to all that have replied to my 'problem'.
Mark, I phoned around and found someone with the old Crypton tuner that had been relegated to the storeroom, problem was he did not know how to set it up for a RR!! All the other advice I have taken on board and will work through the options over Christmas. I have sent for a new distributor cap and will give that a try. On the road the car moves well, picks up speed and at 50 - 60 mph there is no noticable missing. If I come to a traffic light or a junction pull up still in Drive then the car is giving this slight judder.
Thanks again for taking the time to reply, I will report back as soon as I have something positive. Clive
(Message approved by david_gore)
Post Number: 4
|Posted on Monday, 28 December, 2015 - 00:24:
Greetings to All,
I think I can now give an update on the problem I was having with the Silver Spirit. All the advice given was noted then listed to give me a check list to work through. The new distributor cap arrived just before Christmas, so today was my first free day to have a look at resolving the ‘problem’.
As mentioned previously I had changed the plugs, rotor arm and ignition leads. I did try disconnecting the easily accessible plug leads but at idle speed there was no significant change. It was ‘juddering’ when the car was in Drive. As there was not anyone available I felt confident enough to sit with the brake pedal firmly depressed with the car in Drive while I took the plug leads off I decided to give the rest of that check a miss!!
I checked the dashpots and cleaned the pistons to ensure free travel. So now it was time to fit the new Distributor cap that would also give me the opportunity to check the ignition leads were in the correct order (I have been known to put them on incorrectly!!). I did a static check on the timing to make sure the rotor arm was opposite A1.
Turned on the ignition started straight away, after warming up in Park I could not detect any faltering or missing, moved into Reverse then Drive just a smooth tick over, the juddering had stopped.
Out of the various cures I tried I would say the Distributor cap was the culprit and replacing it has cured my ‘problem’.
Once again thank you all for the advice and may you and your cars be trouble free throughout 2016.
Post Number: 1865
|Posted on Monday, 28 December, 2015 - 10:39:
Great news Clive and thanks to all who contributed their suggested cause[s] for the problem[s] - there is no substitute for the shared experience of others when it comes to persistent hard-to-diagnose problems.
gordon le feuvre
Post Number: 97
|Posted on Thursday, 31 December, 2015 - 06:47:
This is just reminder re Michael Vass comment. Th e correct cap requires breathing, that is to say it has cut outs around the edge that touches dizzy body. This was a modified cap to eliminate the caps being "blown off" by crankcase fumes coming up dizzy shaft. My mate with carb. turbo just had this happen. Local fix is just drill hole on cap, to let gas escape-cheap fix!
Robert Noel Reddington
Post Number: 824
|Posted on Friday, 01 January, 2016 - 10:58:
I blew a dizzy cap off with WD40. No damage done . All good fun. I think the cap was cross firing inside only 45 degrees between posts. Look for the thin grey line of burnt carbonised cap material. What ever they are made from. Keep the old brush and spring as a spare.