Hi everybody this is my first time here my name is Nigel from the Isle of Man so cannot get much info over here , please could you help with my new addition to the family 1972 mk 1 stag original engine , I have found that my vac unit on the distributor is not holding vaccumn is this required as it has electronic ign fitted thanks
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Hi Nigel
Welcome. This should normally be posted in the main forum, but to answer your question yes, if you have the usual electronic ignition (Lumenition etc), where the distributor still does the vacuum advance as well as the advance related to engine speed. Unfortunately there are no new vac units available, but they can be reconditioned.
Note though, that there are a couple of electronic units on the market where the advance is carried out electronically (one being the Aldon Amethyst). -
Hello Nigel.
Welcome to the forum. Suggest you speak to Martin Jay, the distributordoctor. http://www.distributordoctor.com. He is the expert and sells quality parts, maybe not the cheapest but good.
John.Comment
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Welcome to the Forum Nigel.
You do need a working vacuum advance even with electronic ignition or the timing runs very retarded at light throttle and significantly increases fuel consumption. Having fixed it you will find you need less throttle to hold any steady speed.
NeilNeil
TV8, efi, fast road cams and home built manifolds. 246bhp 220lbft torqueComment
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Nigel
Welcome. As Neil says you need the vacuum advance. Race engines often don't use it but for road cars it's needed. The electronic ignition -well most of them - just replace the points in supplying a spark. The centrifugal and vacuum advance elements are still required to get the spark to the coil at the right moment.
NickNick
72 Federal Stag. TV8, RHD & MOD Conversions.Comment
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Thanks for that I will now be on the search for a vac unit cheersComment
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Just be careful when buying. You need the original unit with the connection pipe coming from the end, not the side of the "cone". I don't know what planet the latter ones were designed to work on, but they are certainly not for our atmosphere.
MikeComment
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They are probably vacuum retard units for emission purposes, I found this out when I bought my first TR6. It was a USA carb model which I converted to PI but used the carb distributor body. The whole thing was as flat as a fart until I realised I had a vacuum retard unit and was running with the ignition about 30 degrees retarded from where it should have been!Originally posted by Mike J View Post
NeilNeil
TV8, efi, fast road cams and home built manifolds. 246bhp 220lbft torqueComment
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The retard units have the pipe coming from the rear/side, whereas the advance pipes are at the front as you would expect.Originally posted by flying farmer View PostComment
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A polluted Dissy
A polluted Dissy.
Dissy2.gif
Aust/Federal pollution series.
better pic
Dissy3.png
1 - vacuum advance
2 - pollution retard
The Stag uses a Lucas 35 D8 Distributor.
The Rover 3500 uses a Lucas 35 DM8 Distributor.
How much difference between them? besides ignition modules/advance weights
AllanLast edited by pagan; 15 March 2015, 09:03.Comment
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They have very little in common. Rotate in opposite directions and different bases.Originally posted by pagan View PostComment
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Rotor arm and dissy cap the same.Originally posted by V Mad View Post
The direction of rotation is relevant to either the gear at the bottom and/or the motor.
Dissy internals are one thing, but the British car industry seems to use a lot of similar components.
Wish I kept the Rover spares I had, so to check.
AllanComment
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HI try wins I think I had my one from them
Regards TerryComment
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