| Author | Message | ||
     Randy Roberson Frequent User Username: wascator Post Number: 852 Registered: 05-2009 |
Hi, I’ve been away for a while, preoccupied by Ford Model Ts and Pierce-Arrows, so I am behind on my RR work. I got in the ‘77 to move it and the shifter motor is balky. I can fiddle with the shift lever and get it to work, but it obviously needs contacts cleaned or some sort of maintenance. Also, it will start right up but idles poorly and has low power with back-spitting when pushed at low speeds, like it’s lean. I swear I cannot see an adjustment on the two SU carbs, like I can see on the 1970 Shadow. Please advise on either issue as I cannot go out amongst the common folk like this… | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3255 Registered: 06-2009 |
Randy, With regard to the Carb, it is very well worth your time to have a look at and thorough read through Chapter U5 in the Shadow II/T2 workshop manual. Figure U29 shows you the adjusting screw location behind a tamper-proof cap, which must be removed. There may be other adjustments you might want to try first. Brian | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 810 Registered: 05-2016 |
The twin SU HIF7 carbs are set at the factory and usually don't need any adjustment other than balancing them. The mixture adjustment screw has a tamper proof cap to discourage fiddling. It sounds like you have either a manifold leak (maybe at one of the hoses)or possibly crud in the carb float chambers or clogged fuel filters. There are 3 fuel filters (one small one at the carb end of the fuel feed pipe to each carb) and a main fuel filter under the car. Sticking dashpot pistons is another possibility, have you topped up the dashpot oil ? | ||
| Randy Roberson Frequent User Username: wascator Post Number: 853 Registered: 05-2009 |
As a matter of fact, I think the dashpot oil in one or both carbs is gone; why I don’t know. I remember finding one low past time I studied this, and adding some. I will have to refresh my memory in the Manual before further proceedings. It’s great to get back and catch up on all the Forum happenings. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 765 Registered: 10-2008 |
Randy, check the mixture weakener is not stuck on all of the time. Had a similar problem with my Shadow1 ( different weakener set up )and also the 1982 Mulsanne which I believe is similar to the Shadow2 set up. Mine are UK cars. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2484 Registered: 09-2004 |
And not forgetting the Opus distributor starting to fail! Classic signs of the reluctor etc failing, starting ok then misfires as it gets warm with eventual FTP. When cold all is well again on the initial start up. Scope to test. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 854 Registered: 05-2009 |
At least the Opus is gone; replaced with a Pertronix unit several years ago. Weakener valve is a good idea; thanks! | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2527 Registered: 09-2004 |
If the Pertronix is ok then maybe the ballast is failing if fitted! Have also known coils to give problems as you state. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3274 Registered: 06-2009 |
Definitely check *both* solenoids - weakener and anti-run on. The anti-run-on solenoid on LRK37110 had gotten sticky at one point and stayed stuck open. The behavior was much like your description. Brian | ||
| Randy Roberson Frequent User Username: wascator Post Number: 858 Registered: 05-2009 |
My anti run-on solenoid has 12 V from either wire to the metal housing but zero V between wires, all with ignition on; also no click from ignition off to ignition on and back. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 867 Registered: 05-2009 |
I have satisfied myself the anti-run on solenoid is bad, so I have ordered a replacement. It has a significant value as a core so don't just toss one if you have a bad one. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3284 Registered: 06-2009 |
Randy, It's also very common for both of these solenoids to "become sticky" from years of dirt and no attention. In a very great many cases, giving the inside a good shot of WD40 or similar (pick your penetrating light lubricant of choice, I have used others, too) then letting it sit for a day or two before hooking it up to a test lead and activating/deactivating it will often cause the mechanism to spring back to life and remain that way for many years afterward. I replaced both on SRH33576 but revived one on LRK37110. Brian | ||
| Randy Roberson Frequent User Username: wascator Post Number: 868 Registered: 05-2009 |
Additional question: what size are the rubber vacuum hoses associated with the anti-run-on and weakener systems? Mine are hard as Chinese arithmetic and need to be replaced. I tried 5/16th inch fuel line but the fit on the metal barbs is slightly loose. | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 777 Registered: 11-2017 |
You can solve the loose factor with a short piece of shrink tubing over the metal tube. It may take a second layer until snug. You can also buy small pinch clamps, but best to have a snug fit to start. Measure the diameter of the metal tube with a caliper and you will find it is best to use tubing sized in millimeters. Nothing wrong with hard vac hose as long as it doesn't have to move and is tied down accordingly. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3288 Registered: 06-2009 |
Randy, If this is not time critical I can check the silicone vacuum tubing I used, but not right now. I had a total right knee replacement yesterday so my mobility is, shall we say, limited at the moment and will be so for a bit. Brian | ||
| Jeff Young Frequent User Username: jeyjey Post Number: 463 Registered: 10-2010 |
I hope you're on the mend quickly, Brian. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3289 Registered: 06-2009 |
Thanks Jeff. This has, at least so far, involved a lot less pain and discomfort than I had anticipated. But, today is my first outpatient PT session, so fresh hell awaits! Brian | ||
| Omar M. Shams Grand Master Username: omar Post Number: 2194 Registered: 04-2009 |
All the best for a speedy recovery Brian. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 2312 Registered: 05-2012 |
Best Wishes for a quick recovery Brian. | ||
| Graham Phillips Frequent User Username: playtime Post Number: 485 Registered: 03-2019 |
G'day everyone,... Sorry to hear about you needing a knee replacement. I do hope your recovery go's better than me when I rolled my ankle, then a week later just when I was able to walk again I did it again only this time I got a hairline fracture in my ankle bone. I am only now mobile again. Get better Brian. Don't be like me! Graham. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 870 Registered: 05-2009 |
UPDATE: examination of the '77 Silver Wraith II's anti run-on and weakener solenoids, revealed a chafed wire lead on the anti run-on solenoid, so I obtained a used replacement. This made no difference in the wonky engine performance, though: Engine starts easily and runs OK until the choke starts opening, at which time it starts to chuff intermittently in the exhaust. Manual manipulation of the choke toward closed will instantly make this stop. In driving it is way down on power and chuffs very noticably, such that it is hardly drivable. I wonder if one carb could be blocked or dry of fuel... | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 365 Registered: 01-2014 |
Pull the hoses off the float bowl vents and see if it runs OK then. Carbs are way lean or you have a big vacuum leak, which is likely related to the anti run on solenoid. On the HIF's it's easier to pull the float bowl vent hoses off the weakener assembly than remove them off the carb body. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 367 Registered: 07-2018 |
I don't own a Shadow and my advice comes from what I've learned here on this forum and the US one. You have to take the weakener system off the table and eliminate that as the problem, you're just throwing parts at it right now. Disconnect it at the float bowls and block off the weakener system so not to create a vacuum leak, leave the connection open to the atmosphere at the floats. Find where the weakener system connects onto the intake manifold and disconnect that _ plug off the port into the intake manifold that the weakener system was connected to. Technically because you disconnected it from the intake manifold you don't have to block it off where it was disconnected from the float bowls, but do it anyway. Take it for a drive and see if the problem is solved. If it still does it, then you may assume it's not the weakener system, but even then from the sounds of things, all the vacuum lines are hard and probably cracked and need replacing. They may be leaking, also assume that any joints in the vacuum lines may be cracked. Inspect all the lines carefully, replacing them one at a time _ do not pull all of them off at once. Sticky dirty solenoids is another problem as mentioned earlier. Note that having no oil in the damper tubes will not cause poor running over-all. All that does is keep the engine from getting a big gulp of fuel when your foot gets heavy _ you will get poor fuel economy, and that's it. Having to ad oil is normal, the engine use it up as it leaks out the bottom of the damper tubes. With all that said, don't start messing with the mixture until you have taken everything else off the table, there is no reason for the mixture to suddenly go out of adjustment. It sounds lean, so the weakener system has to be dealt with first. Also check the dash pot pistons and make sure they rise and fall smoothly, sticky pistons will also cause your problem. This was also mentioned earlier in the thread as well as other things like dirty clogged fuel filters and such, but you have to eliminate the weakener system as the cause first. Keep in mind too that it may be that and other things as well, but my disconnecting the weakener system you will have a place to start. Purchasing an inexpensive vacuum pump takes the guess work out of finding vacuum leaks. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 871 Registered: 05-2009 |
All good advice and the things I am concentrating on. I replaced the anti-runon solenoid because the wire was chafed and it was intermittant, depending on moving the wire. That said, there was no air entering the weakener system because I have the filter disconnected and the hose plugged. Vacuum leak(s) possible of course. Exactly what it seems like, just have to find it. I do not plan to touch the mixture as it is not likely the issue. Engine ran fine but something happened suddenly, just have to find it. | ||
| Trevor Hodgekinson Frequent User Username: wm20 Post Number: 286 Registered: 11-2006 |
Working on the ago old adage 50% of fuel problems are caused by ignition faults while 50% of ignition faults are routed in the fuel supply . Suddenly = bad HT lead - bad plug - bad dizzy cap | ||
| Randy Roberson Frequent User Username: wascator Post Number: 872 Registered: 05-2009 |
Very possible of course. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 874 Registered: 05-2009 |
Today I tried a different ignition coil; no change. | ||
| Randy Roberson Frequent User Username: wascator Post Number: 893 Registered: 05-2009 |
I have resumed work on this problem (poor running) after rectifying the electrical problem at the switchbox and cleaning contacts in the shift switch. As before: engine starts normally but starts shaking as the choke comes off. The exhaust manifold is noticeably cool on A-bank. I suspect there is a problem with B carb: maybe float stuck and not admitting fuel. Saga continues. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 165 Registered: 02-2015 |
I had a problem with my 1978 Corniche DRH32489 some years ago. Steve Sparks suggested a leak in the inlet manifold gasket. When running the car I squirted carby cleaner around the manifold gasket area, and the roughness disappeared. ie the car was running too lean particularly at low revs. I used silicone goo to seal up the leaks and the car ran beautifully. Steve then replaced the inlet manifold gaskets which were badly damaged on one bank. I think I have posted info on this on another topic. I will chase it up and let you know. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 166 Registered: 02-2015 |
The other post is also on the Silver Shadow Series page entitled "Removing the needle seat from a Solex 4A1 carburettor". The latest posting was 22 June 2020. I really should have created a new thread to make it easier for people when searching the topic. |
