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Old 12-29-2012, 12:30 PM   #21
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is it just me or is the divider thing not supposed to be knife edged like that?

I thought I read somewhere that you want it to have a similar shape as an airplane wing, and not knife edged like /\
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Old 12-29-2012, 12:33 PM   #22
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I don't think he's done just yet.

I'll wait right here for more pics to come by.
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Old 12-29-2012, 05:40 PM   #23
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Originally Posted by 18psi View Post
is it just me or is the divider thing not supposed to be knife edged like that?

I thought I read somewhere that you want it to have a similar shape as an airplane wing, and not knife edged like /\
I wonder....


Yes I read it too

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Originally Posted by Miater View Post
I don't think he's done just yet.

I'll wait right here for more pics to come by.


What I find intresting, is no one has asked about the valve guides.....
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Old 12-29-2012, 06:06 PM   #24
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What I find intresting, is no one has asked about the valve guides.....
It's "obvious"
You have remove them for the port work and plan to put unmodified (old/new) guides back in there.
The trade-off of poorer valve guidance is not worth it for the slightly increased flow.
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Old 12-30-2012, 01:20 AM   #25
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Originally Posted by NiklasFalk View Post
It's "obvious"
You have remove them for the port work and plan to put unmodified (old/new) guides back in there.
The trade-off of poorer valve guidance is not worth it for the slightly increased flow.
+1 That kills valve guides.
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Old 01-01-2013, 05:23 PM   #26
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If I can find a cheap head, I may give this a go myself. I have some junk valves to work on the chamber too.
MT.net head porting for dummies?

Sorry for the threadjack but,
Would something like this kit from Eastwood get it done for a DIYer?
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Old 01-01-2013, 05:56 PM   #27
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can you please flow a stock port on that head, i never got to do it on my head and would like to know gains over factory, i would also like to compare my flow number vs yours, nice write up and looks real nice. i know what you mean about flow bench bores and actuators. our superflow was set up for v8's i had to make a dohc actuator and a 85mm bore stand
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Old 01-02-2013, 11:14 AM   #28
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Quote:
Originally Posted by NiklasFalk View Post
It's "obvious"
You have remove them for the port work and plan to put unmodified (old/new) guides back in there.
The trade-off of poorer valve guidance is not worth it for the slightly increased flow.
Quote:
Originally Posted by emilio700 View Post
+1 That kills valve guides.
True true.. And porting the intake bowls is a ton simpler with the guides out if the way.


Quote:
Originally Posted by doward View Post
MT.net head porting for dummies?

Sorry for the threadjack but,
Would something like this kit from Eastwood get it done for a DIYer?
Thats a decent base kit with the burrs that are in it, you will want to order some more sand paper rolls, 10 is just not enough

Quote:
Originally Posted by ctdrftna View Post
can you please flow a stock port on that head, i never got to do it on my head and would like to know gains over factory, i would also like to compare my flow number vs yours, nice write up and looks real nice. i know what you mean about flow bench bores and actuators. our superflow was set up for v8's i had to make a dohc actuator and a 85mm bore stand
Ill start getting some flow data once I get a stand and actuator built.
I have started to gather some of the parts for the stand.
Superflow is just a bit expensive on the stands they sell.
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Old 01-02-2013, 11:19 AM   #29
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Originally Posted by emilio700 View Post
+1 That kills valve guides.

dont hate.

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Old 01-02-2013, 12:09 PM   #30
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Originally Posted by Braineack View Post
dont hate.
You may have figured out, I don't have much hate in me. But yeah, removing the area of the port roof that supports the valve guide then cutting a significant portion of the guide away results in rapid valve guide wear. Not worth the flow gain IMO. I have seen over 230cfm at around .370 (BP6D intake) @ 28 hg on a skillfully ported head. That's about a 12% gain with stock cams. One can have their cake and eat it too.

Miata heads always die from valve seat wear and the OEM springs allow float at modest RPM. Why speed that process up? It makes as much sense as razor thin zillion angle valve seats that flow like mad and are toast in 20 hours.

I might cut away the valve guides for a Nationals grenade motor but not on an HPDE or DD build.
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Old 01-02-2013, 12:35 PM   #31
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My head still has depressions where it ate a screw in the squish area on #4.
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Old 01-02-2013, 12:47 PM   #32
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My head still has depressions where it ate a screw in the squish area on #4.
singh groves?
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Old 01-02-2013, 01:26 PM   #33
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exactly!
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Old 01-03-2013, 11:44 AM   #34
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Braineack... The port work looks good, and the guides touched at the end will have little effect on anything.

Emilio... I will agree, cutting the guides down is not the best thing to do on most heads.It does kill the support of the valve stem and wear will occure faster.

Most all the time I have seen excessive seat wear on a sinter metal or powder metal seat insert is from a valve job that did not control seat run out, and the valve had to pound the run out from the seat.
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Old 01-14-2013, 05:00 PM   #35
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Quick question: removing/reinstalling the valve guides - is it just a matter of pressing or pushing or hammering them in/out? Or do you have to do something fancy like freeze/heat up the area like I've seen on some youtube videos of fancy shmancy engines?
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Old 01-14-2013, 05:16 PM   #36
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18psi.. it really comes down to the head.
But thos is the most common method.

https://www.miataturbo.net/engine-pe...er-head-64857/

Some times a guide will not just press out, then heat is used.
If heat does not work, then the guide will be "shelled out" That is a PITA, the guide is reamed paper thin, then chipped out.
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Old 01-14-2013, 06:11 PM   #37
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got it. thanks sir
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Old 01-25-2013, 09:47 PM   #38
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Smile Cleaning the combustion chambers.

BP combustion chamber porting.






The stock chamber.
Blue lay out dye has been applied.
A used HG is the template.


The main reason to do this is to remove the factory casting imperfections, along with removing potential hot spots.


Bevel the sharp edges.





Now the head is ready to be cleaned, and have the guides installed, and the valve job done.
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Porting the 99/00 BP head-img_1740.jpg   Porting the 99/00 BP head-img_1746.jpg   Porting the 99/00 BP head-img_1748.jpg   Porting the 99/00 BP head-img_1752.jpg  
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Old 01-25-2013, 10:36 PM   #39
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HOLT ****! That looks nice!
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Old 01-26-2013, 12:49 AM   #40
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Is there a better than stock option for valve guides?

It seems head porting on BP motors doesn't make much more power. Is it worth the effort to take the guides out, port it, new (better?) guides, and reassemble. Plus the head rebuild while you're there. How much is 12% more flow help in a turbo car? Not doubting it wouldn't, but how much.
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