Thread: Porting intake
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Old 03-18-2004   #57 (permalink)
RallyBob
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Re: The other way . . .

Originally posted by tekenaar
I understand the reasoning for running the wedge peak to divide the front two cylinders from the rear two for a progressive carb (32/36DGxV, Solex), but has anyone looked at doing it the other way (divide outer and inner cylinder intakes for a synchronous carb (38DGxV, 40DFxV)? Advantages, disadvantages, problems?

Bob?

Personally, my reasoning for using the peaked divider was two-fold. First of all, I had always noticed fuel puddling at the bottom of the plenum, so I wanted to remedy this. Secondly, when porting the manifold to extremes, the plenum volume increases substantially. So by putting the peaked divider in place, I can actually reduce the plenum volume while increasing the flow from the porting.

Regarding running the divider the other way. I think it would partially block the entrance to the runners, and might impede the ability for both barrels of a synchronized-opening carb to feed one runner at a time (since only one runner at a time has a full 'signal' at a given moment).

I never took the time to go much further with manifold development. I figured the next logical step was to scrap the stock intake completely, and build one from scratch, develop that and then have them cast in quantity. Of course, then I retired from the Opel parts business, so I never got much further than a few sketches.
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