Weber intake question

[bobcowan]

Yes, there is. The rough intake ports help keep the fuel in suspension until it gets to the pocket. If you polish that up real nice, it will make the engine run worse at low rpm's. If you're using EFI, that's not an issue.

Also, be very careful about how tall you make the intake ports. If you're running big heads, port matched to a 1262R gasket, some manifolds can't be ported that big. Before touching the manifold, set it on the mounted heads and get the basic fit. They do a gasket match. Without the carbs/TB's, you can look right down the ports and see how they fit together.

[Bill D]

Thanks Bob

[Bill D]

I found some very good information on this topic. I thought I would share it

"This is def one of those subjects that can get people heated up but here's what MotoMan has to say about the matter...

Homework

Why Not Polish The Ports ??
Doesn't Air Flow Better on a Smooth Surface ???

Remember that the ultimate goal isn't "flow" ... it's POWER !!

The intake port is going to flow both fuel and air. The problem with fuel is that, since it weighs more, it's difficult to keep it evenly mixed with the air as it follows the contours of the port.

Boundary Layer

The next time you drive a car in the rain, notice that when the car is going 60 MPH, the rain drops go up the hood of the car at walking speed. That's because the smooth surface of the car creates what's known as a boundary layer, and the portion of that layer of air that's nearest to the surface is almost still.

The same thing happens inside an intake port. Except instead of raindrops, it's fuel droplets that will run down the port wall slower than the air. That causes a serious change in the fuel air mixture by the time it reaches the cylinder, ruining much of the engine's potential power.
Polishing the port walls will ensure that this happens.

The phrase "Port & Polish" always makes me laugh ... I think the idea came from 70's Hot Rod magazines or something. Anyways, the last thing you want to do is polish your ports !!!

Instead, by making a series of rough 60 grit lines that purposely go against the flow, the "boundary layer area" will be turbulent, and the fuel will stay suspended in the air.

Remember: Rough is Good !!"