M30B35 head mod questions

[7173bmw]

I'm building a 3.5L motor for my 73 E9 project. I have a head that will mate to a 6pack of Webers. 3 questions:

1. Should I have the Weber carb manifolds port/polished to match the head?
2. There are double intake springs in the head...what's that all about?
3. Are there better rockers to use with carbs? Cam will be upgraded 292

Thanks!

 

[Mike Goble]

You don't want to polish the runners of a wet flow manifold, a florentine finish will help keep the fuel in suspension and make it to the cylinder in a readily combustible form.
If you are matching the ports, scribe your manifold port about 0.4 to 0.5mm smaller all around than your head port. This will give you a cushion when grinding so you don't get a wall in the transition, which disrupts the flow into the head.

 

[TodB]

Paul Burke lurks on this site sometimes. Amongst other things, he grinds his own cams from billet. I saw specs where he gained ~50 hp on stock B35 with one of his cams. He'sa wealth of knowledge about these engines.

You may want to have a chat with him about your ideas.

 

[7173bmw]

Thanks! I'll do a search now!