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Porting 12g940 Head
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Author:  simonw [ Thu Jun 06, 2019 4:27 pm ]
Post subject:  Porting 12g940 Head
Just a bit of a photo diary of the porting. I have not done this before and am enjoying the adventure!

Main goals are:

- Get rid of the valve guide hump in both inlet and exhaust ports
- Smooth out the inlet entrance.
- expand the exhaust entrance to roughly coincide with gasket size.
- deburing the ports as best as possible .

I am using a few pictures and GR’s cutaway of a full race head to gauge how deep I can go with the bowl in the inlet valve throat ..probably using the wrong names for all these locations but you can inform me as we go if you like.

Image

Here are some pictures:

Image




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Author:  simonw [ Thu Jun 06, 2019 6:28 pm ]
Post subject:  Re: Porting 12g940 Head
Image


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Author:  simonw [ Sun Jun 23, 2019 10:57 am ]
Post subject:  Re: Porting 12g940 Head
Can anyone chime in whether its worth getting rid of those seat cuts in the chamber?


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Author:  Mick [ Sun Jun 23, 2019 1:10 pm ]
Post subject:  Re: Porting 12g940 Head
Its pretty easy work, and has been performed on mini heads since moses was a child. Why not!
Author:  simonw [ Mon Jun 24, 2019 4:46 pm ]
Post subject:  Re: Porting 12g940 Head
ImageImage
Just finished the rough in .
Putting the inserts in next
Then will blend the chambers


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Author:  GR [ Mon Jun 24, 2019 6:04 pm ]
Post subject:  Re: Porting 12g940 Head
Hi Simonw
That burr is not really the right thing to use for getting under the valve throats, if you would like I can send you a couple of round stones I had made for getting in there, one is 1inch and the other is 3/4ins both have longer shafts on them they work really well for that.
Your doing a good job, we all had to start some where :D if you need any help just give me a call.
Graham Russell
Author:  simonw [ Mon Jun 24, 2019 7:01 pm ]
Post subject:  Re: Porting 12g940 Head
Exceptional offer Graham thank you !
I will PM you details


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Author:  simonw [ Tue Jun 25, 2019 8:46 pm ]
Post subject:  Re: Porting 12g940 Head
Image

Just seeing if i can get the chamber heights all identical


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Author:  GR [ Wed Jun 26, 2019 7:16 pm ]
Post subject:  Re: Porting 12g940 Head
Hi Simon
Did you get the stones they were sent over night?
Graham Russell
Author:  simonw [ Wed Jun 26, 2019 8:25 pm ]
Post subject:  Re: Porting 12g940 Head
Yes thanks GR just picked them up this afternoon .
Really appreciate it !
Now .... how do I use them properly? :)
Are they to get that real bowl shape where the valve guide humps were ?


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Author:  GR [ Wed Jun 26, 2019 8:49 pm ]
Post subject:  Re: Porting 12g940 Head
Hi Simon
The big one will do the inlet bowl it will give you a nice shape, remove the guide boss, but where the divider is use the smaller one as the big one is to big
For that.
As I told you don't worry to much about the exhaust it will be fine,do that and then we will talk about the short side.
Graham Russell
Author:  simonw [ Thu Jun 27, 2019 2:56 pm ]
Post subject:  Re: Porting 12g940 Head
ImageImageImage
I love these things ! Thanks graham


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Author:  bluehishouse [ Tue Jul 23, 2019 12:13 pm ]
Post subject:  Re: Porting 12g940 Head
More pics! I did some after reading the article among other things, im hopeful it will go alright. Fair bit more came off this 202 later. Image

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Author:  simonw [ Sun Aug 04, 2019 1:41 am ]
Post subject:  Re: Porting 12g940 Head
Image

So head is completed and decked , just need to set up valves and springs now


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