7 mm exhaust valves stems?
Turbo Mini Forums

I think some have used 7mm valves stems,
could you tell me if that's right and how many boost have you used with them?
fab

Why use 7mm? Get some 6mm ones. They're easily available for our applications.

??
could you tell me where and in which size?I need 37.7/31
thanks
fab

I mean going form 7,12 to 7mm is just a waste of time. Much fucking about for littel gains. If you fit 6mm however, now we're talking.



http://www.med-engineering.co.uk/product_d...24&vlang_id=168

http://www.med-engineering.co.uk/product_d...16&vlang_id=160

I believe Swiftune makes them as well.
My only concern, is that the outer part of the valve guide is VERY big. I've been thinking about pressing a sleeve into the guide hole in the head, and fitting Vauxhall 6mm guides which are much slimmer on the outside. Even less restriction in the path of air.

sorry ,
I think I wasn't clear enough,
Idoen't want to downsize from 7.12 to 7, but to know if some have used the 7.12 unstead of the 8 mm turbo exhaust ones, because I have a very well prp head which I don't want to change the exhaut valves for lrger stem ones.
6mm seem very small for tuboing it could make the valve sticking, isn't?
cheers
fab

Well. it's 6mm in the C20LET engines. Although they've got two , I guess it's OK. Less restriction= more heat that passes just by :)

yes, I think most people are using 7,12 exh valves. 8mm is just plain stupid. Overengineering.

thanks Veg,

or lettuce to his mates ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

minispares race 214n stainless exhaust valves fab

thanks Benross,
I'll go for minispares, would you recommend rimflow (17 unstead of 10£) over minispares or just minispares one, also they do not advertise the 37.7 ones could you help to source somes. I've traveled around the net but didn't found them.
fabrice

Why on earth would you like so big inlets? It's just begging for trouble. YOu'd be better off fitting 35,7/31. As you cannot fir 31mm exhausts with a 37,7.
Is your head unleaded?

cannot fit 37.7 with 31?
that's my current head:

and it's allready 37.7/31
why use it for turbocharging and not a 36/30 or 36/31?
because I can make a turbo spooling at his max boost from 2400 rpm's so don't need to improve torque/lag,velocity. what I want is to lower the torque number to something acceptable for trannys and tires traction in the lower revs then improve the torque along the revs and so improve revability, untill this I allways had troubles to make an a seri turbo reving well (with power increase that you can feel)past 6000, the idea is to take it to 7500 .
fab

fab,

minispares race valves EN214N stainless the Biggest they do
single grove collet application

inlets for 12g940 casting 37.2 mm
part number C-AHT55

exhausts 31mm for 12g940 casting
C-AEG107
as above fab


rimflows only go to 36.6mm

contact: north@minispares.com

F.A.O RICHARD

or phone 01423 881800
you need the uk code as well fab

Edited by BENROSS on 10th Nov, 2006.

Steve,
minispares valves are interestings/well priced, good source for the 31 exhaust but I have to find a set of 37.7 inlets (my head already have this size, the valves stem are well worn and I can't downsize) .I'll enquire from them if they can source them...

i've heard from everyone that the minispares valves are excelent,

for the 37.7 valves Stuart Gurr may be worth a look he doesn't list them on his website but does have bigger ones, so he may have a source. (below lifted from www.vmaxscart.co.uk) I think Stuart uses the Minispares valves quite a bit, well he used them in my head anyway.

Valves:
New mini race 214 n 31.5, 27mm £25 each
Standard type 35.7 or 29 mm £8 each
Race type 214 n heat treated , 35.6, 29, 3, 37.5mm, £10.50 each
Race type 214 n large 38.2, 32mm £18.20 each
Turbo 32mm with 8mm stem £20 each

one place that do have 37.7 is (the devil) Minisport ( they fit them in the race 7 port) no idea what the quality is like though. also I can't get on their website at the moment.

i know fab, e mail richard a minispares north

the other route like mini13 says stuard gurr v max scart

and minisport

just had a look on minisports website, (it must have been down last night)

they do 37.7 but they have long and short valves??? the 37.7 is only avalilable long.

http://www.minisport.com/classic-mini-shop...ng-product.html

the part number starts REC could this mean they are a Paul Ivey race Engineering Components valve? if so they should be a good valve as they make the Rimflo's.

thanks alls ,
emails to minisport and minispares sent (Ive also asked minisport if their valves from Paul Ivey)
I'll keep all the info collected on this thread , perhaps it will usable.
What i have found yersterday is that the chromed stems valves are something desirable for turbocharging, and that renault gt turbos have 7mm stems, knowing how many boost it can take.It confirm that a 7mm stem isn't a trouble and that 8 mm are overengineered
fabrice

Paul Ivey'c valves are as far as I know not chrome stemmed, just plain stainless steel. This works great, but the don't wear well. The Minispares valves are tuftrided so they are great.
Which guides are you using?

I still don't like the big inlets you've got, but I see that you've got no choice. THe exhaust could grow almost 0.5mm in a turbo engine. That means that the gap between the valves will be extremely small.

Veg,
I don't think/know that all Ivey's valves are chrome stemmed (the only I know are the rimflow type)
but I would like some as it's best to transfer heat from the valve .
I'm using bronze/mang guides, said they are the best.I completely agree with minispares valves quality, but their is no 37.7 listed .
I see why this head spec troubling you, but you're wrong, I have over choices, this head is part of my though about turbocharging a mini,I would have prefered a 37 or 37.2 for reliability in mind but can't afford a new longman head at this time, this one have deported exhaust valves guide so not so tight with inlets.I'll give it a go.
fab

Edited by fab on 12th Nov, 2006.

Fab,

I have used Rimflo valves with std stem since 1996. No problems whatsoever. One thing that still puzzles me though is the vavle seat recession. My current head suffers from the recession despite liberal amount of Redline additive. The exhaust seats used to have 3 angles, now they are worn to one 45 degree angle. The valves are pristine. Mileage is about 22000 kms. Does anyone else have similar problems ?

jukka , perhaps the thinner valve is running a lot hotter , and so eroding the seat faster ,due to less heat transfer up the valve to the guide ,and more heat conducting out through the seat ?
regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Yeah that makes sense but the Rimflows are really bulky compared to race valves. Besides the seat width is no where near the race standards, they are 1,5 mm wide which should be more that enough even for turbo use.

Have you considered inserts Jukka? I mean after the head has recessed, you'll need this anyway I guess.

I agree. Rimflos are bulky. Very bulky.

Hi jukka!
that's long time, good to meet you again! you have pm
about the valves 1.5mm seats should be ok this seat recession ennoying me as, when this head will have no more good seats it will be craped.which was the cam used , springs load? 1.5's on it? if my memory ok you were not using that much boost! do you think that I should use 8 mm stems?, but then bulky will not be enough
regards
fab