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Connecting distributor to 6 twin carbs V12
m8kwr - 20/10/10 at 03:11 PM

Assisting my mate with his dax cobra, and he has been told that you are able to connect the distributor the carbs to make the timing better?

Firstly is this information correct?

If so, how do you go about doing it?

Sorry about the lack of information, but thats all i was told, and we are in the dark a little here.

Description
Description


02GF74 - 20/10/10 at 03:25 PM

what I know about this.

the connection of a distributor to engine vacuum advance the timing at high vacuums - namely at idle and low throttle openings is ment to improve fuel economy.

the engine will run ok without this connection.

check that one of the side draught carbs - or vertical in your freind's case - do not have a small tube for vacuum take off; if one does, then connect it to distributor vacuum.

on production car the vacuum is connected to the manifold thus using two or more of the engines cylinders to balance out the pulsing from one cylinder.


mcerd1 - 20/10/10 at 03:37 PM

they are meaning to connect up the vacuum advance on the dizzy assuming the dizzy even has one

It lets the dizzy 'sense' how much load the engine is under (i.e. how hard its working) and adjusts the timing for better throttle response and fuel economy

the problem with a muti carb setup is that each cylinder has its own seperate vacuum - so if you connect it to just one the signal you get 'pulses' rather than the smooth/averaded out signal you'd get from a single carb (the pulsing signal can confuse the dizzy)
you can conect a vacuum line from all 12 together into a box chamber big enough to even it out, then take a line from this to the dizzy, but this needs to be sized right to work (don't ask me how big) so most people don't bother


or you could ditch the dizzy completly and fit a fully programable electronic setup - this should be better than the dizzy could ever hope to be


[Edited on 20/10/2010 by mcerd1]


m8kwr - 20/10/10 at 03:48 PM

When we locate the vacuum on the carbs, this fed is then taken to the distributor.

I have not seen the distributor, so do all 6 lines from the carbs go into 1 tube, and then this is fed to the distributor?

Where abouts on the carb should the vacuum be???


mcerd1 - 20/10/10 at 03:53 PM

^^

thats 12 vacuum lines (one per 'choke' )
but they need to join into a larger volume - then a single line to the dizzy


the vacuum take off points will be likley on the inlet manifold just after the carb - but it might not have any at all (because most pople don't bother)




[Edited on 20/10/2010 by mcerd1]


m8kwr - 20/10/10 at 03:55 PM

Many thanks for your help..... I will hopefully be looking later...

If i get stuck, i might just post a close up photo of the carb!!!!


Agriv8 - 20/10/10 at 04:20 PM

that engine looks so 'RIGHT' in that picture sod the fuel consumption or if it doesnt idle properly.

regards

Agriv8


RazMan - 20/10/10 at 06:16 PM

You'll be needing one (possibly two) of these then


snapper - 20/10/10 at 06:48 PM

Does the car have a servo?
If it does you can tap off that for the distributor


Dingz - 20/10/10 at 07:44 PM

quote:

Does the car have a servo?


Don't connect there the reservoir is too big, it will still show a vacuum after you have turned the engine off! so it will have permanent advance. You need small bore pipes so the volume is kept to a minimum.