damajin
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| posted on 29/4/09 at 11:36 AM |
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Distributor vacuum advance goes no-where?
started looking over the engine last night in preparation for giving it a tune up (I bought the car second hand) and noticed that the vacuum hose from
the distributor has been cut to about 3in long and just goes to atmosphere.
Is this right?
Will this give me power / performance / running issues?
Cheers
D
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blakep82
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| posted on 29/4/09 at 11:38 AM |
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it will affect the advance curve... its supposed to go to the intake manifold i think (been a good few years since i saw a vacuum advance dizzy)
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omega0684
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| posted on 29/4/09 at 11:40 AM |
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blake is correct, the vac adv pipe from the dizzy should be connected to the Inlet manifold vac pipes
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Mr Whippy
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| posted on 29/4/09 at 11:41 AM |
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the dizzy will only be advancing the ignition using the centrifugal advance then and not the load sensing effect of the vacuum
Basically you’re loosing power. Is this engine multi carbed?
Fame is when your old car is plastered all over the internet
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flak monkey
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| posted on 29/4/09 at 11:49 AM |
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Incorrect, the vacuum can be left disconnected on the dizzy, and is recommended if you are using twin carbs or throttle bodies as the pulses from the
manifold cause timing fluctuatuations. The proper thing to do here it to buy a vacuumless dizzy, but leaving a std one disconnected is fine.
Essentially the vacuum advance brings in much more advance when the engine is cruising where you can run higher advances due to the leaner mixture
meaning you get better fuel consumption.
All that disconnecting the vacuum will do is increase fuel consumption. But this is more beneficial than erratic timing if you are running on DCOEs
etc.
If you are using the standard single carb though, keep it connected.
[Edited on 29/4/09 by flak monkey]
Sera
http://www.motosera.com
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Mr Whippy
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| posted on 29/4/09 at 12:07 PM |
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you can actually buy dizzys specifically for no vacuum advance like the 009 ones fitted to the bug engines
Fame is when your old car is plastered all over the internet
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damajin
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| posted on 29/4/09 at 12:37 PM |
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quote:
Originally posted by Mr Whippy
the dizzy will only be advancing the ignition using the centrifugal advance then and not the load sensing effect of the vacuum
Basically you’re loosing power. Is this engine multi carbed?
Thanks to all for the advice. Engine is a 1600 x-flow with a single Webber DCOE 40.
From the sounds of it, it won't be too desperate in the immediate future to have it hooked up, but if I have trouble with emissions etc it may
be something to look at. Out of interest, how to the dizzies that are designed to work without this differ, if anyone knows?
Cheers
D
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flak monkey
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| posted on 29/4/09 at 01:06 PM |
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Dizzy without vacuum advance has a solid top plate inside rather than one which is in 2 pieces.
David
Sera
http://www.motosera.com
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britishtrident
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| posted on 29/4/09 at 01:12 PM |
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Vac adadvance is essentially an economy device to allow weaker mixtures at light throttle opennings --- vac advance is practically zero at full
throttle.
You can convert a lucas vac adavance distributer to non vac advadnce by fitting a one piece bas plate or by lockking the two parts of the base
plate together with a screw or pop rivet.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Davey D
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| posted on 29/4/09 at 02:28 PM |
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my old fiat uno 1.0 IE had vacuum advance on the dizzy. didnt seem to make much/any difference if it was connected or not 
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02GF74
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| posted on 30/4/09 at 07:23 AM |
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what emission are you worried about? pretty sure SVA test is visual only
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