Angle milling

Is angle milling after market heads worth the hassle?

The intake would have to be milled as well correct?

What are the pro's and con's?

Angle milling is a way to take more chamber volume out than regular milling. The intake manifold does not need to be milled if the intake side of the heads are milled to match the face. That should be standard practice when angle milling.

Angle milling refers to removing more deck material off of the exhaust side than the intake side when prepping the heads. This will reduce combustion chamber volume, raise the intake runners, and deshroud the valves by moving them closer to the center of the combustion chamber. In effect, you are making a 23 degree SBC head into a 21 or 22 degree head with typical milling. This will increase compression and increase head flow, and hence potentially make more power. The problem is the cost and getting the manifold and headers to fit on the milled heads. As AdioSS said, the heads also need to be reverse machined on the intake face unless you want to machine the manifold. Locally, it costs ~$200-400 to get a set of heads angle milled.

Is it "worth it" to do angle milling? No simple answer - it depends on the goals and budget you have for the project. I'd say that if the heads have been ported and you still need more flow, then consider angle milling. You should decide this as part of the whole package because you may not want to raise the compression, depending where you started.

Rich

Angle milling refers to removing more deck material off of the exhaust side than the intake side when prepping the heads. This will reduce combustion chamber volume, raise the intake runners, and deshroud the valves by moving them closer to the center of the combustion chamber. In effect, you are making a 23 degree SBC head into a 21 or 22 degree head with typical milling. This will increase compression and increase head flow, and hence potentially make more power. The problem is the cost and getting the manifold and headers to fit on the milled heads. As AdioSS said, the heads also need to be reverse machined on the intake face unless you want to machine the manifold. Locally, it costs ~$200-400 to get a set of heads angle milled.

Is it "worth it" to do angle milling? No simple answer - it depends on the goals and budget you have for the project. I'd say that if the heads have been ported and you still need more flow, then consider angle milling. You should decide this as part of the whole package because you may not want to raise the compression, depending where you started.

Rich

Thanks Rich, I thought it would change the valve angles as well. My head need to be milled as the chambers will be too big and I would have to run a pretty big dome to get the compression right. I will talk to the head guy and see what he recommends.

Current valve angle is 20.5 on my 23 deg heads :)

Thanks Rich, I thought it would change the valve angles as well. My head need to be milled as the chambers will be too big and I would have to run a pretty big dome to get the compression right. I will talk to the head guy and see what he recommends.

Current valve angle is 20.5 on my 23 deg heads :)


You might end up with 18 degree heads when you are done ;)

Rich

You might end up with 18 degree heads when you are done ;)

Rich

But would they be comparable to a out of the box or as designed 18 degree head??

I got a good enough deal on the heads that I can put quite a bit more money into them and still be under my target cost.

I got the heads and J2K rockers for less than I had budgeted for just heads:eek:

I was (kind of) kidding. No, they wouldn't be comparable because they would still have the same runners, even though the valve angle would be more favorable. Anyway, taking off that much would require a lot of other work to get the manifold and headers to fit right, could cause problems with creating a thin deck, etc. A good machinist would know the practical upper limit to how much could be angle milled.

Rich

I was (kind of) kidding. No, they wouldn't be comparable because they would still have the same runners, even though the valve angle would be more favorable. Anyway, taking off that much would require a lot of other work to get the manifold and headers to fit right, could cause problems with creating a thin deck, etc. A good machinist would know the practical upper limit to how much could be angle milled.

Rich

Thanks I'm a big time newb when it comes to this valve angle crap :p