custom intake manifold for Webers

[ZZZ0MG]

I'm trying to make a custom manifold for a 1G head for 2 Weber 45 DCOE carbs, how did/would you make the runners go from the square ports of the head to the round input from the throttle bodies?

 

[bastarddsm]

If it was me I would just flatten a round tube enough to stay inside the 1g port, and then maybe fill the sides to match. That all hinges on what your goal is. For example if I was going to do 4 side draft carbs on my 1g all motor car that I'm trying to make 400hp with, I'd probably be looking for the 60+mm carbs. The displacment and RPM will take all the port you can give a 1g head. If you are building a mild cruiser motor, my first approach would be better.

You can leave the port mismatch - you'll only pay a small penalty - provided it's a small intake into a bigger head port. Other way around is bad. I run that on my turbo car non ported Evo3 intake on a 6 bolt head. I tried it on my all motor car, and it hurt it above 7000, but was better below it compared to a good big port SMIM.