Wow it has been a while!!bertvorgon wrote: ↑18 Jun 2020 08:58 Not sure what to say about the balance pipe, I would maybe leave it in as first test. Boost overcomes a lot of flow variability.
What I meant about the secondary is that we milled the secondary bore to a larger diameter, at the venturi point, then, we did a backcut under what is now a very minimal venturi, to give MORE of the venturi effect.
So, we basically made the 32/36 which is the throttle plate size, the actual venturi size is 26/27 MM, so we made the secondary about 34 MM+, really increasing airflow when the secondary is open.
I wish I could remember how much of a cut we did, it is so long ago and I never wrote it down in my log book. Too hard to measure now with the carb in place and booster venturi blocking a measuring tool.
That mod, coupled with my larger cam at the time, really let my engine breath past 6,000-6,500 RPM and 8,000 RPM was easily achieved in 5th gear.
Possibly in this attached picture you can see how much bigger the secondary venturi is, almost same size as throttle.
Another trick for flow is you can mill the throttle shafts a bit flat. All these type of tricks really do increase flow.
Well i am up and running with the twin weber turbo setup!!