Port matching intake or not?

[RRSweden]

I'm restoring my 383 and the old dual plane cast iron intake (2806301), wich I'm intending to re-use, have smaller ports than the 906 heads.

Is it worth porting the intake for better flow?

 

[texas69bee]

I asked this same question about a year ago. It kinda got mixed reviews. My thought... It couldn't hurt.

 

[1778ppr]

From what I’ve read (I’m no expert) it is important to match the roof and side walls for max flow. Leaving the floor mismatched with a short curb actually increases fuel distribution because of the turbulence it creates. The mismatched floor decreases flow but improves the mixture inducted into the chamber.

How important is this? I’m guessing not all that important on an engine producing less than 1hp per cube. Like everything else. The more horse power you produce the more important thing become.

As posted above, it couldn’t hurt. As long as you have it apart, why not?

 

[66Satellite47]

Matching the top & side walls is really helpful. The best thing is to grind under the valve seat. Smooth out the area under both intake & exhaust and you pick up a bunch of power.

 

[RRSweden]

Thanks guys. Now for the practical part What tools to use to grind the cast iron?

 

[dvw]

Useless, spend your time on something that will make a difference. Even when the intake is bigger than the head you'd be surprised how good the stuff can run. I've run Max Wedge intakes on 906 heads and gone 11.60. A guy at work runs a square port intake on oval port heads (BB Chevy) runs 10.20's
Doug

 

[Darthomas]

I think the mismatch turbulence helped me with a 73 340 manifold on my 71 318.
But I was aiming for torque, and only had the seat-of-my-pants dynamometer..
Others disagreed that turbulence could be seen as helpful.

 

[66Satellite47]

In order to remove much material below the valve seat, it's easier to use a carbide cutter, however a stone could do the work. The stone just takes so much longer. A high speed die grinder is the key tool.