whats the difference inbetween a normal head and a big valve head what valves could be used in order to make one if this can be done? i know a lad who said he might do it if i got some info so i was just wundering any info would be good thanks also would it still be compatible with my abd bottom end?

Edited 1 June, 201115 yr by tarn polo

Hey mate, the difference is that the exhaust valves are 63 mm i think, you can still get em from jabba sport.co.uk for around 160 for 4. It requires bigger valve seats so not an easy job. If your getting that done you may aswell get a full port n polish n gas flow done at the same time! Let me know how you go on cos I'm in sheff and want the job doing aswell.

63mm exhaust valves?? From what I've read, the biggest you can go is 33mm inlet and 38mm exhaust. No need to get the valves from jabba, there are plenty of oem valves to choose from depending on what size you go for, people have used valves from 8v golfs iirc.

Matt.

ye ill let you know how it goes, like i said i have someone who will machine it all but wasnt sure on the valve sizes so anymore info would be good

most mk2/3 polo big valve heads have 2mm oversize exhaust valves. Standards are 29mm and the oversize ones are 31mm, these aren't OEM in anything they are specially made, jabbasport is the place to get them from:

http://www.jabbasport.com/store/index.php?...GL40VALVE54130T

Some BVHs have used 33mm mk2 golf valves but these leave very little material between the valve seat and spark plug hole which is prone to cracking, ruining the head. The guy who did my G40 head (who has done tons of polo heads over the years) recommended to not use them.

You can increase the size of the inlets slightly too although not by much really. In a G40 there's not really much benefit in doing this but generally speaking NA engines will respond more to increased inlets than an FI engine.

Thankyou very much haysey I can have a chat with my mate now

I wouldn't bother with a BVH if I was you, the valves are already pretty big. You'd be far better off spending your money on getting a head gas flowed and or port and polished, you could also get some work done on Tge valves them selves? Smaller stems etc.

I wouldn't bother with a BVH if I was you, the valves are already pretty big. You'd be far better off spending your money on getting a head gas flowed and or port and polished, you could also get some work done on Tge valves them selves? Smaller stems etc.

I was guna have the bvh ported and polished and gas flowed anyway. How would the smaller stems help? Am a newbie to vales, valve stem seals etc thanks for the info

Hmmmm reading this is now confusing - help me out guys.

I'm building a nutz G40 in the hope of getting around 230-240bhp

I'm not spending the earth on this build - far from it, so what i want to know is...

I have a mint normal 1.3 head (non mech fuel pump and with 2 oil pressure ports) and i was going to build this up to suit the engine.

Do i go for

1 the port and polish route with some new G40 exhaust valves

2 Mild dremelling in the appropriate places with larger exhaust valves

3 stock G40 rebuild head

4 large valves and porting

I want to stop the power around 240 as the G60 box I'm going to use wont handle it past there

oh - and i dont want the head to cost more then £250 and i will rebuild the head myself

KiZ

Well the stem is a minor restriction to gas flow so the smaller the better.

Regarding the BVH, its up to you at the end of the day.

O ok then thanks for info. Al probly try it out as theres not many GTs I know that have done it thanks anyway

What haysey said!

I'd just measured my turbo downpipe thats where the 63mm came from haha

Edited 2 June, 201115 yr by etches69