3 angle valve job

[EThirty318i]

I have the chance to get one, is it worth it? pro's con's?

[deutschman]

I had one done with a 30/45/62 intake and 30/45/60 exhaust. Any more angle on the third cut makes the angle almost horizontal. It is hard to enplane when I am not looking at it. I did a lot of talking with a VERY good machinist and he said that those angles would work best with the head I had and the way it was originally machined by BMW.
Any ways if you can get it done do it. It is one of the more noticeable things you can do to an m20 head. I would say go for it.

[EThirty318i]

Thanks! and i was just looking at your build thread and noticed you had a 3 angle valve job done haha. BTW I'm in awe! that is awesome! good job! and thank you for the help!

[deutschman]

no problem. make sure you find a real good machine shop that is willing to talk you threw what you are doing. if the guy does not want to talk about it, or even tries to blow you off, find a new guy. i feel if the person doing the work is not interested in what he is doing and loves to talk about it he will do a bad job.

[Dj Buttchug]

theres alot of theory about angle cuts on valve seats ect. Heat transfer is a big deal as well as the valve sealing correctly. Most shops with 3 angle cut anyways. Its vey common.

If your building something for power or boost consider a 5 angle job. More surface area of the valve comes in contact with the valve seat surface thus transferring more heat and creating a better seal...if your just refreshing a 3 will do fine.

[deutschman]

Its also a lot about air flow and reducing interruptions in the flow of air and/or air turbulence. The less extreme angles the air coming into your engine has to move over the better. This is also why many people will try and "port" the intake runners to try and reduce the angled surfaces the incoming air has to flow over. That is a very simple explanation of the idea. Five angle jobs can be a bitch to do, and might not even be possible depending on the head, and the condition the head is in. There is only so much material and surface area to work with.

[EThirty318i]

Thanks guys! that really helps!

[digger]

its best do do these things on a flow bench, unless you know someone who already knows what works best from a good deal of experience on the exact head you are using

[SkiFree]

^^^ x2, otherwise it's an unfortunate case of the blind leading the blind. Find someone local who's willing to take you on as a grunt for a bit in exchange for knowledge.

[deutschman]

its best do do these things on a flow bench, unless you know someone who already knows what works best from a good deal of experience on the exact head you are using

The angles I used were resurched and recommended by a very experienced machinist.

[browntown]

Its also a lot about air flow and reducing interruptions in the flow of air and/or air turbulence. The less extreme angles the air coming into your engine has to move over the better.

I'm no physicist, but I've talked to lots of guys in the hotrod arena and there seems to be some debate about this. Some guys say turbulence in the intake path is fine if not helpful. The engine builder paul burke I talked to over on mye28 and on the phone has pretty much talked me out of port matching the b35 intake to the m90 head. I forget the details but he did testing for Mopar? in the 60's? on the very subject and found the step in the intake flow did nothing adverse. I'm sure I have the story wrong a little, but I remember him telling me about wasteful and meaningful engine work.

You can see his engines on the net. He's a pro

[digger]

The angles I used were resurched and recommended by a very experienced machinist.

experienced with what specifically works for M20 heads for improved performance or just alot of years machining stuff? there is a difference

[Wanganstyle]

here is a properly done m20



exh side clean up (slight to match headers)



chamber:




Intake side opened up:



engine specialities head (RIP Dave cruz)

[digger]

here is a properly done m20



exh side clean up (slight to match headers)



chamber:




Intake side opened up:



engine specialities head (RIP Dave cruz)

pics don't seem to work?

[jamesthebikeguy]

What does a Valve job like Deutchman cost?