| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 1859 Registered: 6-2009 |
In revisiting and updating my firing order diagrams I have come across a conflict of information in the various SZ workshop manuals. TSD4400, the workshop manual for the 1980-1986 model year cars states in Chapter E - Engine, that the firing order is the same as it had been since the SC-II: A1, B1, A4, B4, B2, A3, B3, A2 However, the same document directly contradicts itself if you look at Chapter A, Section A3, page A3-5 (PDF scan page 18):  NOTE: It is my labeling error in the image above where I have "Bentley Eight" which should have been "Turbo R." The Eight is the next column over and it reads "as 1" as you can see. Once you get to TSD4700, the workshop manual for the 1987-1989 model year it gives this firing order for all cars: A1, A3, B3, A2, B2, B1, A4, B4 What I'm trying to figure out is whether the table shown above from Chapter A of TSD4400 is accurate, and that the 1986 Turbo R is the single model year where there is a single "odd man out" as far as firing order goes, or if this is a typo where it should have read 1987 where it says 1986. I want to make sure that I have it right as far as what's correct on this. I would have to believe an owner of a 1986 Turbo R could shed light on what its firing order is and resolve this contradiction. Brian | ||
| michael vass Prolific User Username: mikebentleyturbo2 Post Number: 118 Registered: 7-2015 |
Hi Brian Intriguing eh?, to change firing order you have to change the camshaft profile yes? ,the info I have is Camshaft first fitted to the Turbo R from VIN 13875 and then to all models from VIN 20001. But no odd year. I have 2 dizzys so even harder to work out lol Hope that helps Mike | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1496 Registered: 6-2006 |
EFI instead? | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 3260 Registered: 4-2003 |
Shame the change was required. Shadows and first SZs run just so smoothly like no other V8 on earth because of the innovative firing order. The change to the crankshaft front end, with its extension stud in the early SZ revision, didn't do to well for very long. They were fine on the low-powered cars as the performance declined with low compression and emission controls reducing the mighty R-R V8 to embarrassing Toyota Corolla outputs. Once the performance was boosted by 50% with a Turbocharger they became crackshafts, so the firing order had to change. The cheap solution was to change the firing order rather than to fix the crankshaft problem. Sadly they started to sound and feel like any agricultural Holden, Chrysler, Ford or Chev V8, but the crankshaft noses stopped falling off. I lament that the crankshaft nose was not improved instead of changing the firing order. I like the growl of my Conti R, but it is no way as sweet as the song of my T-Series. As always, the developmental cars at Crewe saw their modifications leak to the lesser models within a few years. The firing order change was no exception, although in my opinion it was a Detroit-style detrimental cost saver rather than sorting out the problem. RT. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1860 Registered: 6-2009 |
Based upon Mr. Vass's chassis-number specific documentation, I am going to update the firing order diagrams I've made to reflect SC-II through 1986 Model Year SZ Cars except Bentley Turbo R with Chassis Number 13875 or Higher [See 1987 and Later for these specific Turbo Rs] for the first and 1987 and Later Model Year SZ Cars Beginning with Chassis Number 20001 [also 1986 Bentley Turbo R with Chassis number in the range 13875 - 19999]. It appears we do have a single year "odd man out" but I cannot see the point in maintaining three separate documents when two will do. That tweaking will occur over the next couple of days along with a few other bits. Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1861 Registered: 6-2009 |
Let's hope these are the "final final" versions.   Brian | ||
| michael vass Prolific User Username: mikebentleyturbo2 Post Number: 119 Registered: 7-2015 |
Hi Brian Thanks I feel honoured I could help an expert such as you! I had a ride in Rod in Frances '81 spirit last week and thought it was my imagination that it was so smooth. Some people thought this was an April fools joke to start with  I never knew about this change. Cheers Mike | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1497 Registered: 6-2006 |
Hi Brian, really great diagrams except the A1 start position is wrong for RR&B. It should start where A3 on the Shadow and B1 is on the SZ and continue round from there. There's a diagram for Siamese dizzys somewhere to. . . Another bonus would be to put the cap clip and vacuum capsule positions in just to help anybody with a car with it out or fitted wrongly? Just a though! Great job | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 3261 Registered: 4-2003 |
I think, Pail, you refer to the plan of the distrinutor caps ie the positions of A3 vs A1. With the distributor correctly installed, A1 points forward to the front of the motor, rotated maybe 5 degrees clockwise, whereas the distributor cap plan above shows A3 there. I'm wondering what is new here. It is all in the workshop manuals and is rather clear there including the change in firing order for the 1986MY Turbos. The information has served well for decades. As noted, the change in firing order was an emergency change to stop crankshaft failures when the motors were tuned to over 300HP. The change was adopted across the range once stocks of camshafts were used up on non-turbo engines a year or so later rather than being scrapped. All SZ motors may be retrofitted with the later camshaft if desired although the motor feel will be different. Early Mulsanne Turbos and Turbo Rs need one unless already retrofitted. Of course, the lead locations in the distributor cap needs to be reconfigured to suit. I understand that the later camshaft may be fitted to SY and S2-S3 motors too. Many S2s and S3s have SY camshafts, and the brake pump lobes are not in the way.. The later EZ58F twin distributors are covered in TSD4737 Chapter E, including the plan of the caps showing where the leads belong.. RT. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1862 Registered: 6-2009 |
Paul, On SRH33576 the distributor cap has pretty much the arrangement I've shown but on LRK37110 the "clock face" positions of the leads is indeed different, though their order "around the clock" relative to A1 is, of course, the same as that's what determines firing order. Both cars run, but the comment I got from another mechanic on LRK37110 shortly before my work on her was suspended is, "It feels like the timing's off by about 40 degrees!" (or some large number, it's been a while now since I had to put that project on hold). SRH33576 can be driven. I wasn't trying to get anything except the firing order correct on the distributor diagram, but if changing the "clock face" relative position of A1 would make it representative of how most cars look when they come from the factory I'd be more than happy to do that. Adding a small bit for the clips and vacuum capsule is doable, too. If a few folks are willing to send me photos of their distributors taken from the birds eye view, with the firewall visible and their A1 lead noted, that would be helpful. I'll have to take a shot from this perspective later today for SRH33576. Since LRK37110's distributor is now installed in her I can't do that car, but the "transplant" which helped me determine that I had a failed distributor after the Christmas FTP two years ago now (I think) didn't change what sounds like the wonky clock face positioning on A1 in that car. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1142 Registered: 5-2012 |
Hi Brian It sounds as if the camshaft on one of your cars has at some time been replaced 180 degrees out. This would account for the different positioning of the leads, which would have to be fitted 180 degrees out to compensate for the camshaft. It would also account for the "40 degrees" comment. As Paul noted, the position of the clips would be very useful. Here is a picture of my 74 SY1  Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1863 Registered: 6-2009 |
Gentlemen, Based on the valuable feedback I have received so far here are the updated diagrams with the distributor wire positions accurately depicted and the clips added based on what I think I'm seeing in Geoff's picture. Other corrections or additions will be most appreciated. My goal is to have something as accurate as possible and that's as easy as possible for "the uninitiated" to understand and get an accurate feel from. Once I have the "all clear" blessing from the reviewers in this cohort I'll then also put the end result up on rollsroyceforums.com. Brian   | ||
| Roderick Waite Prolific User Username: rodwaite Post Number: 156 Registered: 1-2012 |
Hello to all - nothing cogent to add other than I learned the firing order on V8s way back in the 50s from working on Army lorries powered by Ford V8s that ran like Swiss watches - 1.5.4.8.6.3.7.2 - it's unbeatable for symmetry and smoothness. Can't imagine why anyone would want to change it., RR&B included. Thanks Mike, I hadn't even known there had been a change! But Echo is an '84 Spirit, about the last of the 'real' cars, albeit with a measly 200bhp out of 6.75 litres! | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1864 Registered: 6-2009 |
 Well, I clearly did not create the original distributor diagram from direct photographic evidence or observation on SRH33576, as the leads are where they are supposed to be. It's been so long since I did the initial diagram it could be that I just wanted to make sure they were in the correct order, but didn't even look to see about correct physical location. The clips on her, though, are distinctly not at the 12 and 6 o'clock positions. Mind you, this is a direct transplant of the distributor from LRK37110, using the original distributor cap that came with SRH33576, and I never touched a thing as far as adjusting timing, etc., because she ran fine; I've had absolutely no change in driving behavior or knocking, pinging, or lack of power. The original thought was to put this distributor back in LRK37110 and the Mallory optical one in SRH33576. I'm rethinking that now since I have a Lucas I can rebuild or pass on if someone wants strict originality, but the Mallory unit appears to be of much higher quality than the original equipment. That's a decision for another day, though. Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1866 Registered: 6-2009 |
Well, I've had another photograph come in from another Silver Wraith II owner, so I've updated the "through 1986" diagram accordingly. It appears that the location of the cap clips changed over the years from the 12 and 6 o'clock positions to more like the 1 and 7 o'clock positions, so I'm removing the clip reference entirely since it's not helpful and, after all, your clips are where they are. The vacuum advance has been consistently showing between 3 and 4 o'clock, and that is now reflected with the note "where so equipped".  Now, that brings up the question for the 1987 and later cars with single distributor: is there ever a vacuum advance in these at all? My gut would tell me no since I'd suppose that the EFI ECU controls all that, but I also don't know if there were any markets not yet using EFI in 1987 or later model years. Any guidance? Brian | ||
| michael vass Prolific User Username: mikebentleyturbo2 Post Number: 152 Registered: 7-2015 |
Hi Brian Came upon this diagrams you may like Mike   |
