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how much to shave
https://www.ausmini.com/forums/viewtopic.php?f=2&t=57958		 Page 1 of 2
Author:  encho [ Thu Oct 15, 2009 6:37 pm ]
Post subject:  how much to shave
Hi guys
i have a standard 998 that im planning on putting a 12g295 head onto.The
head has 24.4 ml how much should i shave of the head to get a good compression ratio im planning on installing twin 1 1/4 sus,any suggestions would be appreciated.
Thanx Eddie.
Author:  doogie [ Thu Oct 15, 2009 7:08 pm ]
Post subject: 
60 thou can be safely taken off it.

Doogie
Author:  drmini in aust [ Thu Oct 15, 2009 7:17 pm ]
Post subject: 
Measure thickness first, original was about 2.750".
Author:  Phat Kat [ Thu Oct 15, 2009 7:41 pm ]
Post subject: 
drmini in aust wrote:
Measure thickness first, original was about 2.750".


Absolutely, if your intending on taking a fair bit off, make sure you know what you have to start with... Its not overly common but make sure the rocker cover face of the head hasn't been decked at any point too. Otherwise you may think you have more or less than you really do.

On the small bore heads (this is not applicable to the large bore motors... which leads to my question in a sec..) when you have have the head sitting on your bench the right way up, ie you can see the rocker cover side, if you look carefully at the facings for the rocker posts, one of them will have a small oil hole in it about 3mm in diametre. Measure the depth off this hole, then deduct that measurement from the over all thickness measurement of the head and that amount right there is the amount of meat between the deck and your oil galley... take that amount and add .085" to it,,, thats about as close as I ever like to get it... you might be braver than me though :lol: ...

So...

that leads to my question,,,, does anyone know how to check the big bore heads? Damned if I know, I just close my eyes and go for it!!!!!!

Edit: Damn!!! You got a 12G295 too? I thought they were kinda rare.. I have 1... But it seems like everyone on here has one? :lol:
Author:  1018cc [ Thu Oct 15, 2009 7:52 pm ]
Post subject: 
I've got 0.055" taken off of mine and it hasn't gone a gasket. As doogie said, you should be fine taking off 0.060"
Author:  encho [ Thu Oct 15, 2009 7:56 pm ]
Post subject:  the doc is right on
from memory the size is 2.750 or is that 27.5 mm.
and yes i do have one off thse heads i actually found it on the side of the road along with a 12g202 and some other parts :lol:
Author:  Phat Kat [ Thu Oct 15, 2009 7:58 pm ]
Post subject:  Re: the doc is right on
encho wrote:
from memory the size is 2.750 or is that 27.5 mm.
and yes i do have one off thse heads i actually found it on the side of the road along with a 12g202 and some other parts :lol:


:shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock:
I gotta go for a drive down your street some time!!!!!!!
Author:  encho [ Thu Oct 15, 2009 8:00 pm ]
Post subject:  sorry
i jut looked at a pic i took and it is 27.57mm :oops:
Author:  encho [ Thu Oct 15, 2009 8:06 pm ]
Post subject:  again
its 2.757" :oops: :oops: :oops:
Author:  Phat Kat [ Thu Oct 15, 2009 8:07 pm ]
Post subject:  Re: sorry
encho wrote:
i jut looked at a pic i took and it is 27.57mm :oops:


Now now,, turn that frown up side down :D at least you check your first measurement :wink: "'"measure 12 times shave once"""

Please, I know that you found this head and it cost you nothing,, but they aren't very common,,, please actually measure how much meat you can take off before you give it to your machinist and tell him to go shaving it all willy nilly,,

Doogie and 1018 are right, if you have a virgin head (unmolested, untouched) you can take .060" off no worries,,, but chances are you won't, and it maybe that the reason it was on the side of the road is because it was warpped and the previous owner couldn't deck it again for a lack of meat.. Know what I'm getting at?
Author:  sgc [ Thu Oct 15, 2009 8:38 pm ]
Post subject: 
Phat Kat wrote:
Edit: Damn!!! You got a 12G295 too? I thought they were kinda rare.. I have 1... But it seems like everyone on here has one? :lol:


Nah, they're common as.. I've got one as well :lol:
Author:  Morris 1100 [ Thu Oct 15, 2009 8:44 pm ]
Post subject: 
sgc wrote:
Phat Kat wrote:
Edit: Damn!!! You got a 12G295 too? I thought they were kinda rare.. I have 1... But it seems like everyone on here has one? :lol:


Nah, they're common as.. I've got one as well :lol:

I thought it was a requirement for joining the forum to own a 12G295? :lol:
Author:  74snail [ Thu Oct 15, 2009 8:53 pm ]
Post subject: 
26.9cc chambers , 1100 Rimflo valves, has only been surfaced .

[img][img]http://img507.imageshack.us/img507/7963/12g2951100rimflovalves.jpg[/img][/img]



.
Author:  Phat Kat [ Thu Oct 15, 2009 8:53 pm ]
Post subject: 
Morris 1100 wrote:
sgc wrote:
Phat Kat wrote:
Edit: Damn!!! You got a 12G295 too? I thought they were kinda rare.. I have 1... But it seems like everyone on here has one? :lol:


Nah, they're common as.. I've got one as well :lol:

I thought it was a requirement for joining the forum to own a 12G295? :lol:


:lol: man this is funny! As soon as I crawl out from under my little rock and start talking to other mini owners outside of the little group I normally talk to,, My brain starts getting exploded with all this exciting new stuff...

Looks like it just must be that more people cottoned onto the fact you could pinch em off the 1100 autos than what I first thought. Oh well, I'm sure it was a secret at some point :lol:

So does anyone know how to accurately check the 12G940 style heads for meat? I know a couple of rough ways, but I was wondering if anyone had a scientific method?
Author:  drmini in aust [ Thu Oct 15, 2009 9:17 pm ]
Post subject: 
295 was a great head, but unless you run flat top pistons the C/R is too low because of their stupid big chambers. And if you go ripping .100" or more off, they tend to blow gaskets. .060" or so off is fine.

12G940 (and 12G1316) are the same total thickness as a 202, 295, 1456, etc.
But you can take more off without weakening them, as their deck is lots thicker than a smallbore head.
Chambers smaller too.8)
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