Carb billet vs Cast for TB, etc - Any difference?

[68 Sport Satellite]

Some Carb manufacturers (i.e. Quickfuel) offer both billet and cheaper cast versions of the same carb. Besides looks is there any performance benefit for the billet carb such as better heat dissipation or more precise air and fuel delivery due to tighter tolerance on the billet CNC machining, etc.? Or are things like this negligible under normal use and tuning?

 

[Meep-Meep]

My guess is there is no difference from a performance or drivability perspective. Thermoquads are plastic (main bowl only) and that is an advantage because of the insulating properties of the material, but the air could care less if it's passing through an aluminum venturi or cardboard for that matter. As long as the profile is the same it's good.

I once test ran a VW type 1 engine with a putty knife over the intake hole and a pinched off fuel line (so the gas would make a stream). Other than being a bit rich at idle, it fired and ran and had some pretty good response!

 

[satman72]

The billet carb will look prettier. You figure, even on a cast carb body, all the important bits are machined anyway.

 

[RustyRatRod]

Some people erroneously claim the billet is less porous than cast. In ALL my years workin on cars, I have yet to see a porous casting. It's a cosmetic thing and nothing more.

 

[67 coronet]

my fuel guy likes em(billet)because he can get a much nicer finish on the inside when customising them.

 

[68 Sport Satellite]

Some people erroneously claim the billet is less porous than cast. In ALL my years workin on cars, I have yet to see a porous casting. It's a cosmetic thing and nothing more.

Good to know! I think for the most part though that any slight porosity would not show up on the outside surface, but rather be present within the wall thickness. If the molds are gated right, it is not an issue, but billet will technically be a tighter packing density if you know what I mean, although those billets originally came from melted ingots that were themselves poured and are not hammered for any extra strength like a forging.