Posted by Chris Case [108.247.147.90] on Thursday, November 19, 2015 at 18:38:25 :
In Reply to: Re: Dual carbs posted by Sherman in Idaho [72.47.153.163] on Thursday, November 19, 2015 at 16:48:29 :
The size of a carb is set by the diameter of the venturi up inside, that's the restriction. Our 1bbl B&B is only about 15/16". There is room for plenty of engorgement before the hole in the manifold gets restrictive. A slant 6 1bbl, or maybe a Ford 300 cid truck.
What is bad for flow is a disruptive, sharp corner adapter. Or a step/misalignment in the pipes. I used to sell a lot of engine upgrades by having a customer blow into a loose plug boot, first one way, then the other. Try it to see what a little internal step does. Remember you have shock waves blasting back and forth at the speed of sound, no steps allowed either direction.
I make my own adapters, at least 2" tall. Some 4", for better low end flow. Use a steel weldment, or carve a block of aluminum. Woodworking spade bits will work, and a die grinder w/ coarse carbide burr.
Pic is a steel weldment, one bbl manifold to 2bbl BDL.
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