Waffle manifold port size

[Spiderman71]

I am rebuilding the cylinder head from my 1608 with the plan to attach a pair of 40IDF carbs on the stock waffle manifold. I have noticed that the manifold ports are quite a bit smaller than the ports in the head. Should I open up the manifold ports to match the head ports or is there a reason for the size difference?
Thanks.

[MNspiderman]

I would. I run 44IDF's and I ported my intake almost 1/4 inch. I don't have a waffle so i don't know the size to tell you to port it too.

[mdrburchette]

I also port matched mine but it isn't crucial since the intake is smaller and the lip created when the two surfaces are mated doesn't obstruct the flow.

[sptcoupe]

I would match them as closely as you can as any ridge or airflow disturbance caused by an uneven surface match up right there at the intake point can cause the gas to form into droplets and fall out of the intake charge. The ony way you will ever know that is not happening is to match them up as closely as you can.

[fiat218]

can some one show me a picture of a waffle manifold?
the one on ebay said it is and well i looked at other pictures and they are way differnt, the seller tells me just because the top looks like a waffle, is that true?

[sptcoupe]

Absolutely port them to match as closely as possible. You don't want any ridge at all at the juncture of carb and manifold - which meand the manifold port should also ot be any bigger than the 40 mm at the bottom of the carb. If you get it too big, there will be a vacuum there that really upsets airflow. MOst people don't do this, and tnose 38mm ports typically found on the manifolds intended for 40 IDFs cost a lot of the potential HP gain of going to IDFs in the first place. And don't forget to do the dame thing on the other end, as well.