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Combustion chambers on a B6 head before and after. The first picture is a chamber that's been cleaned up a bit, but with little grinding work and no polishing work yet. The after picture is a combustion chamber that's been given grinding work and fully polished.



 

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Very nice! Did you do the work yourself or did you have it sent out? I understand that it is a very labor intensive process. I've got a spare head that I'm in the (slow) process of building up now.
 

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Oh yes, it is an extremely labor intensive process. Especially with the state of the stock Miata cylinder head. The processes used in manufacturing this head seems ancient. The sand casting is very rough. Compared with Honda heads, ours needs much more grinding and only after can you start polishing. With Honda heads, not much grinding is needed.

No, I didn't do my own work. This work was done by a friend who belongs to a family of racers with their own commercial machine shop. He does this kind of work all the time. And the work is partly science and also partly art ... very difficult to describe. Also, this is the kind of work that you can't do yourself without a machine shop. Take a look at how the valves were unshrouded. The cut around the edge of the chamber to open up the valve is something that you can't do at home - that has to be done by a machine.
 

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very smart ... I have a spare head too that I am going to have polished and ported at the end of the year raedy to receive some Muruha cams and cam wheels :lol:
 

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That, my friend, is a thing of beauty.

kevin
 

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No no nothing wrong... just working on building up my car for SCCA CSP class, and since my car is my daily driver I can't afford to have down time. I'm looking for a second head that I can port, polish etc... w/o having to have my car down for any time.
 

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i dont mean to hi jack your thread

if anyone is interested i do cylinder head work
i can do full head porting,valve machining,seat cutting, guide installing,valve unshrouding,cc'ing,clearencing, cylinder head assembly,surfacing,cleaning,and testing using

super flow flowbench
sunnen valve seat cutter

for more info email [email protected]

your head looks good, whats the rest of the setup
 

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Your profile is incomplete. Where are you located? Is this a side hobby or a full-time gig? Do you run your own business or work at someone else's machine shop? How many Miata heads have you done before and do you have any customer testimonials?
 

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LOL anyone know where I can get a +01 Head for less than $500
Hi Chris. Did you ever pick up a +01 head. If not I have one that I don't need since I will be going ALL-Motor with my IRTB's with a '99 head. Also not to take away from this thread even though it is time consuming once you're finished with the port & polish it is very rewarding.

Jimmy
[email protected]
 

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Jimmy,

No I didn't pick up the +01 head, the valve train which was on it was crap (bent valve) I didn't want to deal with it. How much are you looking to get for the VVT head? Any idea how many miles on it?
 

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sorry for lac of info

located in central CT
work in a performance machine shop
do porting on the side, mostly honda heads, nissan sr20 head

i have a 99 head and intake mani for my car thats gonna get work done to it, i will post pics as progress is made.
 

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i have a 99 miata. im thinking of havin my intake and head ported and polished. will it be worth it and how will it efect my car. not really shure on all this, i do mostly body work and paint
 

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I am determined to do my own port/polish. I'll have a 3-4 angle valve job and skimming (50 thou!) done at machine shop, but I am going to do the porting myself.
I am reading everything I can find on it and will not lay a tool to the head till I understand the principles involved - it is not real intuitive.

A couple fundamentals I have learned so far...

1. the intake track should go from a large size (@intake manifold) and taper down smaller as it gets closer to the valves. In cleaning up the intake track, it is important not to open up a "lake in the river" as this will reduce velocity. I have heard it said that it is like a nozzle on a garden hose - small orifice = higher velocity.
When grinding, it is better to leave an area rough if it would require taking so much off as to create a lake - as said above - Mazda heads are rough - must be careful.

2. DO NOT USE HEAD GASKET to match ports. I have been told that the Miata head gaskets tend to be too large and matching to the gasket makes port too large. Ports need to be matched head to manifolds, but also all ports should size match each other - otherwise getting AFR consistant will be tough. Make a best-fit template for the ports that is as small as possible.

3. Don't get into the valve seats... this seems to be a stressful thing to most of the guys who have done porting...

4. Intake track needs to be rough - some shops bead blast the intake track after porting - some just use courser grit and don't polish. Polish exhaust track.

5. Combustion chamber has some nasty rough spots in casting - clean up and polish but make sure not to remove too much if going NA - compression ratio decreases as material is removed - cc the chambers - AFR is at stake.

6. Unshroud valves as much as possible (HOW? - what exactly does this mean and is it something the machine shop should do first?) I understand that the more the head is skimmed (some have gone as much as 60 thou! on NA 1.8 for normally aspirated) the less work needed to unshroud the valves...

Please add to this list based on what you know! thanks!
 
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