21 replies to this topic

[PhilipGCaldwell]

I bought a 12g202 head at bingley yesterday off a 997 cooper, it is unmolested

it is a 'beak type chamber, My intention is to port it as per the yellow bible and fit rimflow inlet and exhaust valves. Im going to deshroud the valves and smoothe the beak out.
I know rimflow valves are expensive and people will say 'why not just buy a 12g295', my reason is 1)they are expensive and 2)if i just chucked on a 12g295 i will learn nothing of how to port a head and generally how they operate. when I have ported it im going to put on twin 1 1/4 carbs (I kno people will say put a hiff on, but i think twins look more aesthetically pleasing) and also get the head skimmed to obtain the correct CR

Does anyone have any porting tips and also has anyone done anything similar with a 202 head and what results were obtained

Edited by PhilipGCaldwell, 01 February 2010 - 10:32 PM.

[Tarks]

ive got the same head on my mk2 cooper ill keep an eye on this thread lol

[PhilipGCaldwell]

these are the valves
Inlet http://www.minisport...ECSV300-02.html
exhaust http://www.minisport...ECSV300-50.html
Vizard has good result using these valves in the yellow bible

[Surfbluegarage]

the yellow bible is a good start on the basics of porting, removing valve bosses, improving flow, valve angles and so on. just remember bigger is not always better try more on air flow and shape. just try and keep it simetricle what you do to one do to the other and if possible match your inlet to your head as this will improve flow.

[In-a-mini]

follow the vizard advise and dont go too big. the 202 head comes from 1098 engines too

[PhilipGCaldwell]

cheers lads, just getting my head round the vizard stuff, not gonna go mad, keeping the valves the same size as original (they are quite a bit bigger than mine already), not gonna go mad with the chamber size either, just want to step out the excessively pointy beak. Im very interested to see what the valves do, I know they are pricey however all the valves need replacing (as they are leaded) so i thought 'hey, if i aint bought an expensive 12g295, i may aswell treat it to the best' )

I have a die grinder and compressor with an assortment of stones

Anyone know a descent head skimming place?

[Surfbluegarage]

kool good choice.. i take it your haveing inserts put in the exhaust seats then? when there in 9/10 there is a lip where the insert has been put in.. grind that lip away. its not criticle as the exhaust gas passes it the other way but removing the step will get rid of any gases catching it on the way out.. every little helps.

[PhilipGCaldwell]

yeah gunna try n get the seats put in, where can i get this done, can minisport do it? I sound fairly clueles, but i only just started this yesterday, still researching and reading

[Surfbluegarage]

yeah mini sport can do them in the machine shop...around about 70-80 quid at the minute i think.

[PhilipGCaldwell]

sweet, will take it there this weekend then, will get it skimmed there after i have ported it all aswell.Only live about 40 mins away so its quite handy

[bmcecosse]

This will cost you a fortune - and give mediocre results. It's not off a 'Cooper' - doesn't have the double valve springs! It's from a Morris Minor - slightly better head than standard Mini - but not much. Not worth fitting 'unleaded' seats either! It will need 80 thou skimming if your engine has dished pistons - 60 if flat tops - but of course CR will then depend on how metal you take out of each chamber. It's SO much easier (and far better performance) to just fit a 940 head! No skimming -just sink exhaust valves by 40 thou. Simples!

[PhilipGCaldwell]

tee hee, i knew you would say fit the 940 bmc i have read many of your posts b4, lol
If i had the engine out of the car i would defo put on a 940 head, but for now its bolt on mods im afraid

[PhilipGCaldwell]

hang on, sinking the exhasut valves wouldnt need the engine out would it, i always thought u had to p[ocket the block with a 940.....im confused!

[blacktulip]

hang on, sinking the exhasut valves wouldnt need the engine out would it, i always thought u had to p[ocket the block with a 940.....im confused!

not always true, you can sometimes "get away" with no pocketing but its a risk that you are taking for it end in tears. personally i would stick to the route that you are taking and see what results you can get. yeah its far easier to fit a 12g940 but then again its far easier to fit a stage 3 head from 01smartc. if i were you i would rebuild the 202, get it skimmed to run 10:1 CR and see what happens. i have just had a standard 998 head skimmed to raise up to somehwere around 10:1 and i will see how it goes once i have done a few last minute bits this week.

[Saxo-Fiesta-Mini]

i have a 1275 mg metro engine and i went for a 12g940 head

ported it with a carbide burr set baught from machine mart £38 and then got a die grinder from tool station for £21
id take ur time as from vizards bible opening the top of the inlet port helps gain the best flow
i opened the top and bottom of the inlet removed the lip and smoothed out the edges so its tons better than a standard 12g940 head

have a look on my progress thread some before and after shots of the head