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12g202 bigger valves?
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Author:  xplosion77 [ Sat Mar 06, 2010 6:19 pm ]
Post subject:  12g202 bigger valves?
hey guys

im going down the forced induction on my 1100 that i will be building, just trying to work out what size valves would be good to put in there with some porting and chamber work?

i have had a look at a couple of articals for head modifications, but not to much on valve sizes.

im thinking of going rim flow vales:
inlet 31.42mm - 1.25"
exhaust 26.5mm - 1.043"

standard
inlet 29.23mm - 1.151"
exhaust 25.40mm - 1"

i would like some opinions as to wether if you could go bigger or this is to big.
also will i have to get new valve seats when modifing the valves?
and where is a good place to buy these parts from.

thanks
Author:  850man [ Sat Mar 06, 2010 6:34 pm ]
Post subject: 
Bring your head down to Martini heads in Greensbourgh, Rob will tell you all you need to know and do a professional job of the reco for you. He has done hundreds of mini heads and is very good when it comes to modifying them. I have been using him for years with all my heads.

Martini Heads
94674044
Rob Webster.
Author:  74snail [ Sat Mar 06, 2010 6:57 pm ]
Post subject: 
And if you want someone a bit closer in Hoppers Crossing the guys at Hoppers Heads are very good, they did a great job on my 12G295 with 1100 Rimflow valves, chambers are 26.9cc , in the photo it does'nt look as good as when I picked it up, it sat on the shelf for a bit

http://www.hoppersheads.com.au/site/


Image
.
Author:  justfanginaround [ Sat Mar 06, 2010 7:50 pm ]
Post subject: 
+ 2 for martini heads

Rob and Jason are good freinds of Dad and have always been very good at what they do
Author:  bnicho [ Sat Mar 06, 2010 10:19 pm ]
Post subject: 
"Hoppers Heads" is actually Hoppers Express Cylinder Heads.

That's who I use too.

They stamp a job number on the manifold face, so even if you lose all the paperwork, they can look it up and tell you exactly what they did to that head previously. Very handy if you have a soggy memory like me. :)

Cheers,
Author:  GT mowog [ Sun Mar 07, 2010 5:34 am ]
Post subject: 
74snail wrote:
And if you want someone a bit closer in Hoppers Crossing the guys at Hoppers Heads are very good, they did a great job on my 12G295 with 1100 Rimflow valves, chambers are 26.9cc , in the photo it does'nt look as good as when I picked it up, it sat on the shelf for a bit

http://www.hoppersheads.com.au/site/


Image
.


Looks like a very nice job there 74snail, however there is plenty of meat in there to get bigger valves in. This is where the biggest restriction is :wink:
Author:  drmini in aust [ Sun Mar 07, 2010 7:00 am ]
Post subject: 
Just watch the size of exhausts valves though, 27mm (1.062") is about it on a standard bore, unless you notch the top of the block.
I've done a few 202 and 295 heads with 33mm inlets and 27mm exhausts (1100S valves, exhausts turned down, springs packed up ~1.5mm).
Author:  xplosion77 [ Sun Mar 07, 2010 11:55 am ]
Post subject: 
i would like to convert the head to unleaded, where would i get new valve seats from or would i just give it to the machine shop to find some?
Author:  850man [ Sun Mar 07, 2010 12:07 pm ]
Post subject: 
Just let the machine shop supply them, they should be able to supply the valves and new springs too, cheaper than what you will be able to buy them for.
Author:  GR [ Tue Mar 09, 2010 7:43 pm ]
Post subject: 
Hi xplosion 77
When putting larger valves in a small bore head make sure they are the 1275 length valve, because if you put a bigger lift cam in with the short valves you may get into trouble with coil bind at full lift, eg re13 and std rockers.
now if you give Lindsay a ring at minisplus he can supply you bigger valves for the small bore heads 1.260 inlets and 1.070 exhaust, but in the 1275 length these valves are race quality valves and are only about $22 dollars each, I now use these valves in my own race engines and customers engines as well, for the 1275 engines he has 1.460 inlets and 1.220 exhausts, I like to use 1.420 inlets so i just turn them down.
GrahamRussell
Author:  xplosion77 [ Wed Mar 10, 2010 8:48 pm ]
Post subject: 
when fitting the 1275 valves, do you still buy the 1100 double valve springs, or are they to short to go with these valves?.

have you ever had a problem with the valves lifting to much and hitting the pistons?

i will be using a re13 cam, but can you get a re13 turbo grind at all, i think i read about someone with one a while ago.

i was thinking of converting to a 1:3:1 rocker gear instead of standard

thanks for your help
Author:  drmini in aust [ Wed Mar 10, 2010 9:49 pm ]
Post subject: 
You generally use Minispares C-AEA526 springs, these are 180lb, and good for up to .495" valve lift and 8000 rpm. They have 1 less coil than most stock springs. You can get these springs from most Mini shops here.

The valves won't hit the pistons, as the pistons are near 1/2 way down the bore at full lift.

GR still does a turbo RE13 grind if you ask. Don't use a stock RE13 for turbo or SC.
Author:  xplosion77 [ Fri Mar 12, 2010 5:03 pm ]
Post subject: 
thanks for that guys, ill let you know how i go with it when i start to get some work done on it.
Author:  DA9jeff [ Tue Jul 13, 2010 10:41 pm ]
Post subject: 
how many hours does it take to do a typical 12g202 port and chamber job? I have a guy lined up and has given a hourly rate but im waiting for a time quote so i know the cost. If people could post what they think is a reasonable price for such a job, that would be great. Valves/seats/springs are all new, just need the cast iron worked over to get the most out of it.

BTW its a 1160cc with a 731 cam, and i am sourcing some modern flatslide carbs (thinking twin 38mm atm) to adapt. For a hill climb car.

Cheers,
Jeff
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