My amplifier died so I decided to upgrade to a SNG Barratt distributor system. Installation was relatively easy but I can't figure out a timing issue i'm having. My old wires were 180 degrees out (rotor pointed to 6B instead of 1A) so I decided to put it back to normal. Found the compression stroke using my compression tester and did static timing. Put wires on and could not get the engine to run. So I pulled everything off went through it again and had the same thing happen. For kicks I then put the wires back the way they were originally and the engine fired up and ran relatively smooth but with a occasional loud backfire. Checked timing using my strobe and found that it was firing at 12 degrees ATDC. (static was set at 12 degrees BTDC) so somehow I'm 24 degrees off. (after going to the end of the adjuster) So I removed the cap again and adjusted with the 3 hex head screws but that only got me to about to about a 20 degree difference. RPM is right at 1000 and I have not tried adjusting the carbs since I wanted to understand whats driving the 24 degree difference? Anyone have an idea on what i'm doing wrong? Thanks in advance!!
Steve
My timing challange
#2 Re: My timing challange
Hi Steve,
Very difficult to answer this one, but I will try to give pointers? How did you set static timing? The Jaguar manual describes this process well, if you don’t have it, I suggest to get a copy but it is in the Knowledge base.
Because you now have the SNG system, you must have removed the distributor, did you get it back in the right place? Again, refer to the manual.
Establishing compression stroke TDC on the V12 can be a slight challenge, since it is so large and heavy to turn over. However, you seem to have done this satisfactorily, perhaps you could check this again with the compression tester, then insert a longish wooden dowel through the spark plug hole to rest on the piston, this will help you establish if the marks on the front pulley are correct.
Fit the distributor with the three adjustable mounting screws roughly mid adjustment in the slots, you can actually make it quite tight, but still adjustable, then tighten later through the slots in the rotor disc, fine adjustment can then be made using the eccentric cam – this should also be set midway to begin.
Make sure the rotor disc is correctly installed in the distributor and the timing marks aligned (the slot/mark on the rotor disc should align with the sensor), also check the air gap from disc to sensor – this is as important as the points gap of a conventional system. I do not have the SNG system myself, but I believe there is no change to this fundamental setting.
With all that set, fit the rotor arm and note orientation, make sure you have the cap fitted correctly and that the correct plug is fitted to the correct post. I did wonder if you could have somehow shifted everything around one terminal, not so hard to do given how many terminal posts there are on the V12.
Dynamic timing should be checked with the vacuum retard unit disconnected (yes I did say vacuum retard!) and preferably with the pipe to the carb blanked off to reduce air leaks (the biggest problem with the V12 control system). As you know, it is difficult to see the strobe marks and adjust the distributor timing single handed – I lift the front wheels, make very sure the car is secure and out of gear and either get an assistant or even use a video camera if I really can’t find a helper, but setting the adjustment screws just right means you can adjust and check with no drift, once close, tighten and start using the eccentric cam.
I have no idea where your particular problem has arisen, beyond the possible incorrect fit of distributor or ignition leads, I would simply star again from scratch – it actually isn’t all that difficult a set up and terrified me the first time I tried it, only to be pleasantly surprised.
Good luck,
Regards,
Very difficult to answer this one, but I will try to give pointers? How did you set static timing? The Jaguar manual describes this process well, if you don’t have it, I suggest to get a copy but it is in the Knowledge base.
Because you now have the SNG system, you must have removed the distributor, did you get it back in the right place? Again, refer to the manual.
Establishing compression stroke TDC on the V12 can be a slight challenge, since it is so large and heavy to turn over. However, you seem to have done this satisfactorily, perhaps you could check this again with the compression tester, then insert a longish wooden dowel through the spark plug hole to rest on the piston, this will help you establish if the marks on the front pulley are correct.
Fit the distributor with the three adjustable mounting screws roughly mid adjustment in the slots, you can actually make it quite tight, but still adjustable, then tighten later through the slots in the rotor disc, fine adjustment can then be made using the eccentric cam – this should also be set midway to begin.
Make sure the rotor disc is correctly installed in the distributor and the timing marks aligned (the slot/mark on the rotor disc should align with the sensor), also check the air gap from disc to sensor – this is as important as the points gap of a conventional system. I do not have the SNG system myself, but I believe there is no change to this fundamental setting.
With all that set, fit the rotor arm and note orientation, make sure you have the cap fitted correctly and that the correct plug is fitted to the correct post. I did wonder if you could have somehow shifted everything around one terminal, not so hard to do given how many terminal posts there are on the V12.
Dynamic timing should be checked with the vacuum retard unit disconnected (yes I did say vacuum retard!) and preferably with the pipe to the carb blanked off to reduce air leaks (the biggest problem with the V12 control system). As you know, it is difficult to see the strobe marks and adjust the distributor timing single handed – I lift the front wheels, make very sure the car is secure and out of gear and either get an assistant or even use a video camera if I really can’t find a helper, but setting the adjustment screws just right means you can adjust and check with no drift, once close, tighten and start using the eccentric cam.
I have no idea where your particular problem has arisen, beyond the possible incorrect fit of distributor or ignition leads, I would simply star again from scratch – it actually isn’t all that difficult a set up and terrified me the first time I tried it, only to be pleasantly surprised.
Good luck,
Regards,
Regards,
Simon
Series III FHC
Simon
Series III FHC
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#3 Re: My timing challange
Simon, thanks for the tips. I did pull the distributor again yesterday and started from scratch. Embarrassed to say my initial installation must have been off by one cog because when I finished this time the car started right up. I had no problem turning over the motor with a large 7/8's wrench I have and also have no issues seeing the timing marks since I have a lift in my garage. (working under the lift makes this whole process so much easier!) This time when I was done, I was able to use the adjuster to get it to 15 degrees BTDC and the engine was running great. I will now take your advise and pull the cap, loosen the 3 hex heads and re-adjust so I can get to the prescribed 12 degrees. Even off by 3 degrees I was amazed what a difference the new system makes. It now starts hot on the first crank just by turning the key. It also definitely has more power.
Thanks
Steve
Thanks
Steve
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#4 Re: My timing challange
Simon, one other item I forgot to address. I have no vacuum line going to my distributor and as far as I can tell the advance mechanism on the old distributor never had one. Is this normal or a problem? The instructions for the Barratt system said connect the vacuum hose "if" your car has one? I was surprised none existed since I'm use to working on the older American v8's and the always have a vacuum advance line.
But as I said in the previous post, the engine is running great now even when I punch it pretty hard.
Steve
But as I said in the previous post, the engine is running great now even when I punch it pretty hard.
Steve
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#5 Re: My timing challange
Hi Steve,
I wouldn’t be too embarrassed about being a cog out, it’s too easy to do on a gear driven distributor, at least it’s easier to check and reset than some units I have worked on in the past. I envy your ease of access with the lift!
As to following my recommendations to set up of the distributor, the aim really is to end up with the eccentric cam adjuster pretty much central when the timing is set – this will give maximum range of adjustment with minimal disturbance when fine tuning in future.
As to the vacuum unit, the V12 E-type uses a vacuum retard unit to promote better emissions, rather than the more common vacuum advance. You will note that the take-off point for the vacuum unit is on the opposite side to most vacuum units i.e. on the same side as the distributor, rather than on the opposite – pointing away from the distributor. It senses vacuum right at the butterfly of the LH rear carburettor and as such has very little effect when the butterfly is wide open. I admit to not fully understanding the setup, so I am not going to advise any further than that – it’s next on my list of things to research and understand, but there is a lot of info available regarding the unit, much of it on this forum. However, I have yet to fully study this and decide which information is accurate, which is subjective and which is just plain wrong!
Also, the various markets for the car had different emission control systems – my car is thankfully a very early UK spec with the least amount of equipment fitted. I am keen to keep emissions down, but from the evidence I have seen, the emissions control systems are not that reliable, sap power and when not functioning well, arguably increase, rather than decrease the level of emission. Anyway, with a simple system on my car, I have little real experience of the systems on other market cars.
For some reason, the vacuum unit is prone to failure; my new unit lasted only months and I carried out a home repair on this supposedly non-repairable unit. Because of this and perhaps more so because the unit is seen to have an effect only at low rpm/idle, many people disconnect the vacuum pipe and report no problems. If your pipe is disconnected, I suggest you find it and either reconnect, or blank the pipe to prevent drawing air into the LH rear carb, which will make it perform differently to the other three. The connection point is below the butterfly and a little awkward to get to – most leave the pipe in place and blank it remotely.
Whilst discussing vacuum, the major source of issues with V12 E-type tuning seems to be air/vacuum leaks. There are an inordinate amount of potential sources for air leaks which play merry hell with smooth running and tuning of the car. I recommend you take some time to familiarise yourself with the potential sources of leaks and eliminate them with new hoses, plugs, clamps, clips, seals, gaskets and tightening of associated fasteners. Emission Control systems increase the potential for leaks by providing even more joints in the system.
Regards,
I wouldn’t be too embarrassed about being a cog out, it’s too easy to do on a gear driven distributor, at least it’s easier to check and reset than some units I have worked on in the past. I envy your ease of access with the lift!
As to following my recommendations to set up of the distributor, the aim really is to end up with the eccentric cam adjuster pretty much central when the timing is set – this will give maximum range of adjustment with minimal disturbance when fine tuning in future.
As to the vacuum unit, the V12 E-type uses a vacuum retard unit to promote better emissions, rather than the more common vacuum advance. You will note that the take-off point for the vacuum unit is on the opposite side to most vacuum units i.e. on the same side as the distributor, rather than on the opposite – pointing away from the distributor. It senses vacuum right at the butterfly of the LH rear carburettor and as such has very little effect when the butterfly is wide open. I admit to not fully understanding the setup, so I am not going to advise any further than that – it’s next on my list of things to research and understand, but there is a lot of info available regarding the unit, much of it on this forum. However, I have yet to fully study this and decide which information is accurate, which is subjective and which is just plain wrong!
Also, the various markets for the car had different emission control systems – my car is thankfully a very early UK spec with the least amount of equipment fitted. I am keen to keep emissions down, but from the evidence I have seen, the emissions control systems are not that reliable, sap power and when not functioning well, arguably increase, rather than decrease the level of emission. Anyway, with a simple system on my car, I have little real experience of the systems on other market cars.
For some reason, the vacuum unit is prone to failure; my new unit lasted only months and I carried out a home repair on this supposedly non-repairable unit. Because of this and perhaps more so because the unit is seen to have an effect only at low rpm/idle, many people disconnect the vacuum pipe and report no problems. If your pipe is disconnected, I suggest you find it and either reconnect, or blank the pipe to prevent drawing air into the LH rear carb, which will make it perform differently to the other three. The connection point is below the butterfly and a little awkward to get to – most leave the pipe in place and blank it remotely.
Whilst discussing vacuum, the major source of issues with V12 E-type tuning seems to be air/vacuum leaks. There are an inordinate amount of potential sources for air leaks which play merry hell with smooth running and tuning of the car. I recommend you take some time to familiarise yourself with the potential sources of leaks and eliminate them with new hoses, plugs, clamps, clips, seals, gaskets and tightening of associated fasteners. Emission Control systems increase the potential for leaks by providing even more joints in the system.
Regards,
Regards,
Simon
Series III FHC
Simon
Series III FHC
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#6 Re: My timing challange
Simon, thanks again for the tips. I'm traveling right now but will figure out the vacuum deal as soon as I get home in 10 days. I suspect my car was set up on a California spec (the worst in the US). Its been in Hawaii all of its life however and I'm only the 3rd owner. I picked it up 6 months ago from owner number 2 who had it for 25 years. The last 8 it just sat covered in a garage. Its In amazing shape for sitting that long. I did have to replace the steering rack due to leaking seal and I do have drips all over which I will fix over time. I've already done belts, hoses, plugs, wires, brakes and a number of relays to get everything working again. Time will tell what else goes from having sat so long, but it is a fun car to tinker with since its very different from most of my other toys!! I never heard of a vacuum retard before. I'll also have to do a little research on that 
Steve
Steve
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