Vacuum Manifold/balance Tube

[grannyknot]

Here is a pic of the intake manifold on my engine,

 

I would like to install a vacuum manifold/balance tube so I can take advantage of the vacuum advance feature on the new dizzy.

Would 4 vacuum take offs from the 4 inner intake runners be enough to even out the pulses or should I take vacuum from all 6 ?

Thanks,

Chris

 

[beermanpete]

The vacuum advance is usually connected to ported vacuum and only needs to connected to one carb. The ports in your photo (not drilled on 4 of the 6 runners) are manifold vacuum and will result in full vacuum advance at idle.

[grannyknot]

The  123Ignition distributor that I installed in the spring is programable and I think it it is capable of ignoring

a vacuum signal at any rpm, idle in this case. I would just like to bring down the fuel consumption while cruising and the load is low.

[zKars]

Granny, you're on the right track. That 123dizzy can do it for you. Use as many cylinders as you can AND use a fuel jet or something similar to make a small orifice to further smooth the signal.

[madkaw]

Chris ,

Look at my triple set up . I made a balance tune from a fuel rail.

The 123 ignition is using a map sensor if I understand correctly , so a strong vacuum signal would be best.

[grannyknot]

Thanks guys, I posted the same question on Hybridz and TonyD suggested that as long as there is a restrictor in the vacuum line, that I should only need to tap into one of the runners, so I'm a bit confused.

Maybe I should contact 123Ignition and find out from them the minimum vacuum signal the dizzy requires to work and then do some measuring of the vacuum from my engine.

[khughes]

Hi Grannyknot

Did you get any further with this? i am just installing triples with a very similar manifold, just bought the 123ignition module and am researching to head down the same road

[grannyknot]

7 hours ago, khughes said:

Hi Grannyknot

Did you get any further with this? i am just installing triples with a very similar manifold, just bought the 123ignition module and am researching to head down the same road

I did but never really got a chance to try and test it, shortly after this I decided to sell that engine and go with a bmw s38 engine. I was pulling vacuum from the back of the carbs. I know I have some pics of the finished set up but can't find them at the moment, I'll post them when I do.