12 Valve Head questions

I recently had the intake shelf milled off my head to run an intake runner but they claimed they could not machine it completely flat. Wondering what guys are doing to to achieve a flat surface across the head.

I'm attempting to build a wicked 12 valve daily drivers. so far I have a 12mm injection pump flowing 540cc of fuel and a 4k gov(but will run 4,300 rpms) a set of 5x18 dual feed injectors all from Northeast Diesel Service of Missouri. A 63/67 HX35 with billet compressor wheel over top of an S475 with a billet wheel and race cover. Ultimate goal is 900-1100 hp.

Any help is much appreciated.

99 Dodge 3500 eclb w/ ZF6 6 speed

Well... Nothing is 'Completely Flat'.
But if they can't get it reasonably flat, take it to any other machine shop. If they do engines (decking heads and blocks), they should be able to do this no problem.

I believe you are talking about the flange not being completely flat with the rest of the head or having a very thin area for sealing? Yes, that is common with stock 12v heads. The after market ones we sell have additional material that allows the total side that mates with the intake to be flat, which gives additional sealing area.


I'd go for a bit more cowbell than the 475 and I would look at a touch more injector. At approximately 1.7hp per cc, the full 540 will put you just above 900 if timing, injector depth, drive/ boost ratio, and flow through the head are all correct. I'd focus on putting the throat of the port at 89% of what valve diameter is.

Cheers,

Zach

How soon do you think you will have your new street head available?