| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 365 Registered: 6-2009 |
Today was "measure the resistance" day and it's introduced more confusion/uncertainty than clarity for me. I drove SRH33576 to the garage today so that I would have another car to compare to. Here are the results: Wire Resistance (Ohms) to Cyl LRK37110 SRH33576 ------------ -------- -------- A1 16.5K 7.0K A2 16.8K 1.5K A3 14.5K 1.15K A4 17.0K 5.37K B1 23.0K 17.5K B2 24.2K 15.4K B3 16.7K Not Tested B4 19.4K Not Tested I checked and rechecked each measurement and got the same results over multiple tries. The differences in values between the two cars, particularly for the A Bank wires, are stark (or maybe it's just because I don't know what these numbers actually mean). SRH33576 runs very smoothly. LRK37110 does not. Does this data suggest a problem with the plug wires? Brian | ||
| David Gore Moderator Username: david_gore Post Number: 1277 Registered: 4-2003 |
Hi Brian, Did you check the type of spark plugs fitted to the two vehicles i.e. were they resistor or non-resistor versions? There is another thread on this forum where the relationship between resistor/non resistor plug leads and spark plugs is covered: http://au.rrforums.net/forum/messages/17001/12294.html Perhaps my post dated 20th July 2012 and later posts might help; whilst it was not relevant to solving Rod's problem, there is some useful information..... | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 366 Registered: 6-2009 |
David, To be honest, the answer to your question is, "no." It never occurred to me that there would be any difference between a 1978 and 1979 SY "two series" cars. Any research I've ever done into the OEM and replacement plugs for these cars have resulted in the same plugs coming up. I don't know whether they're resistor or non-resistor type, though. I'll have a look at the thread you reference. I'm hitting the stage where I feel like I'm so very, very close to finding "the magic trick" to finally getting this car running normally that it's actually becoming very frustrating not having any small successes recently. Brian | ||
| David Gore Moderator Username: david_gore Post Number: 1278 Registered: 4-2003 |
Hi Brian, The type of leads and plugs used on any car of this era entirely depends on who was maintaining the car, any problems that needed to rectified and their personal preferences. Resistor plugs usually have an "R" in their designation. No rhyme or reason is involved........ | ||
| Laurie Fox Frequent User Username: laurie_fox Post Number: 99 Registered: 6-2004 |
Just to complicate things remember that there is a spark gap in the distributor which has to be jumped as well as the spark gap in the plug. The plug leads are not actually connected to anything until the gap in the distributor ionises (presuming that this gap ionises first). The 8 gaps in the distributor (one for each cylinder) may not all be the same. The position of the rotor arm when the spark occurs will also be different according to the amount of advance provided by the bob weights etc. This may just be a red herring since B420EY (Mk VI) never had any trouble for 50 years or so (300.000+ miles) with distributor rotors etc. largely left to look after themselves. If there is an insulation defect in either the rotor arm or the distributor head (carbon tracking etc.) it may affect more than one cylinder. Laurie | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 367 Registered: 6-2009 |
I'm having a closer look at what's involved with the distributor as "next on the list." I do believe that this has the "Opus I" electronic guts rather than the old-style stuff. It's really annoying (to me, anyway) that she runs very smoothly at any speed somewhat above idle to really above idle, but won't idle. Brian | ||
| David Gore Moderator Username: david_gore Post Number: 1279 Registered: 4-2003 |
Brian, Do not forget to check for cross-over arcing between the HT leads under the cover plate on the cylinder head for each bank. I found a useful way to check for arcing was to use an old AM radio tuned to a vacant top-end frequency and move the radio above each bank of the engine. Any arcing will be result in a loud staccato burst of static that will vary in frequency with changes in engine speed. Removing the cover plates should but not always reveal evidence of arcing. Aged leads under the cover plates are prone to insulation breakdown over time. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 370 Registered: 6-2009 |
David, Thanks and will do. The HT leads/plug wires on this car appear to be original (pretty much like the majority of the stuff on the car). Given that the thing has a total of 26.5K miles on it in 34 years that's not all that surprising. At the same time, I'm amazed that a full rebuilding of the carbs was done at 23K miles. The documentation from the dealer notes, "R&R and overhauled carburetors; replace needle valves and seats; adjust floats," all done on 11/22/2004 at 23,061 miles. The car has only traveled just under 3500 miles since then, and virtually all of that between 11/2004 and 5/2007. Brian | ||
| Kevin Lagden Frequent User Username: kevin Post Number: 80 Registered: 7-2009 |
I'm going to quickly jump on this thread. I was told that the leads on my Shadow SRH19305 are also original, having covered some 217,000kms. When I asked about costs and how long it would take to renew, my then local mechanic told me about 8 hrs and at $ 120 per hour, plus the new leads. I thought I would leave them for a while. | ||
| Geoff Wootton Prolific User Username: dounraey Post Number: 175 Registered: 5-2012 |
I replaced mine - 50 bucks. This really underlines the fact that a Silver Shadow is a low cost car to run IF you do the work yourself. If not, you're looking at big bills (quite warranted, given the labour intensive nature of most jobs on these cars.) | ||
| Kevin Lagden Frequent User Username: kevin Post Number: 81 Registered: 7-2009 |
Geoff How long did it take you? Kevin | ||
| Chris Browne Prolific User Username: chrisb Post Number: 109 Registered: 2-2010 |
Hello everyone, Just to add my experiences to the mix. Replacing the plug leads is yet another one of those jobs on a Shadow which is relatively cheap to do in terms of cash, but very labour intensive if done properly. The HT leads are threaded through tight fitting metal conduits bolted to each rocker cover which are quite difficult to remove without scratching the rocker covers. The leads can't be removed without taking these conduits off first. There are also two support brackets, one on each bank, which are bolted to the back of each cylinder head. The back of the engine is very close to the bulkhead so the bolts are difficult to reach and work on. There is an added complication in that the bolt which holds the A bank leads also fixes two other brackets to the cylinder head so when refitting, you have to line up three fixing holes and then try to start the bolt in its tapped hole in a very confined space. It is a two handed job but there is only space for finger tips to work. My comment about doing it properly is based on having seen two Shadows where the metal conduits have been left off allowing the HT leads to flap about as on a lesser car - definitely not a method befitting a Rolls-Royce or Bentley! You will need to allow a good six to eight hours to do this job depending on how much tea, coffee, beer, whisky etc. it takes to get you through it. Kind regards, Chris | ||
| Geoff Wootton Prolific User Username: dounraey Post Number: 176 Registered: 5-2012 |
Hi Kevin It took me all day first time but I suspect I could do it now in 2 to 3 hours. I agree with everything Chris has said. The brackets at the rear of the engine have to be removed and access is a problem. My solution is to perch on top of the engine on my homemade "bench", http://au.rrforums.net/forum/messages/17001/12559.html which makes things much easier and quicker. My car is an SY-I and I suspect the spark plug leads can be fitted a little more easily than on the SY-II as there are less obstructions. On the SY-I the A bank leads can be made up on the workbench and then fitted quite easily. This is not true of the B bank leads as there are various obstructions. I found the easiest way to fit the B Bank leads was to first fit the spark plug leads inside the conduit that bolts to the rocker cover. This is done on the workbench. I then placed the conduit in place and fed the loose wires under the various pipes, around the back of the engine and through the rubber moulding. The metal clamp can then be fitted and re-bolted to the rear of the engine. The leads can then be trimmed to length at the distributer end. I also agree with Chris that taking the time to fit the leads correctly is far more satisfying than just drooping them over the engine, a sad sight indeed. Regards Geoff. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1508 Registered: 4-2003 |
High tension leads are one bit of the engine that is so obvious yet so frequently ignored. Thirty years ago when I lived in the States the practice was if you took your car in for a service they would, as a matter of course replace the distributor cap, rotor, points and condenser if fitted, as well as plugs and plug leads. Then they would start the engine and tune it secure in the knowledge that the basics were on spec. I have to admit I have not changed leads in a car for a few years but when I did, if I had the slightest doubt about them they would be replaced. I used to use Thundercords in Sydney but they are no longer in business. The new source of these parts is Performance Ignition Services in Nunawading Melbourne - http://www.performanceignition.com.au. If you access the site, note that there is a separate internal address for Australia. The previous Sydney people helpfully had the dimensions of all the wires on our cars at least the post-war ones and they apparently do quite a bit of work for various repair people in OZ. Bottom line - talk to Roy at the place and organise new leads. They will be the correct gauge and length, the latest materials, black and numbered and ready for you to thread through all the bits. Lastly, be aware that the distributors on these cars were made by the Prince of Darkness and are about as up to date as my war-time ration card. These Nunawading people can select and set up a brand new distributor for your car which will outlast you. The only bit they must have is the drive cog at the bottom of your distributor's shaft which meshes with the bronze gear at the end of the cam shaft. You will as likely also be advised to replace the coil on your car. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 379 Registered: 6-2009 |
Bill, Thanks for these informative offerings. Brian |
