Scirocco Register

It's really not common for those heads to crack badly. I know the guy who did all the heads for GTI Engineering (+ does TSR and other tuners) and he rarely sees a cracked one. Sometimes they crack a little bit between the valves, but hardly ever enough to cause a problem.

I did buy one ages ago off club gti,was going to get it looked at by a bloke that builds speedway bike engines,but then i later decided i was going 9a,as i could get more power easier,than trying to squeeze it out the old dx lump.
That had cracks between the valves,in the combustion chamber,sold it on a few months back.
Going to crack on with it in the morning,got the Janspeed to tinker with too,might have to weld that up a little though,as got it free off someone on here :D and there is a bit of filler stuff between the join.
I will be flumoxed if it`s still trying to suck air in once i put it back together ! Took my mates compression tester back now,but i will grab it again and do another test once it`s running,hoping lapping the valves in will give better results,may have just been head bolts needing a torque down,i think the guides have been done in it`s life,and may not have done the re tighten after so many miles thing !
And on the subject of my mate,only a young lad 20 something,he is into his jet engines !! And built one at home in his garage,runs on gas,has car points supplying spark,until it`s running,then it self ignites,makes a hell of a racket,had it running just down the road from my house,in a layby !! wearing ear defenders etc,well funny.
Dropped off the tester,and he showed me his current project,building one with a turbo on it,bloke is a genius,never seen owt like it,this one starts spinning with compressed air,then gas,then runs on kerosene,have to get him to send me some pics,mental,he wants a shaft driven turbine thing on his Fireblade,flipping Cambridge uni engineering place gave him a job on the strength of the first one he built !1

Oh god !!!!
Guess what ?
I have been out there since 10 am,back together ,running just,flipping starter is about dead,have to hit it every time you want to turn the engine over
It`s running but it`s still doing exactly the same as it was doing before,sucking instead of blowing,if i don`t hold the throttle open it just dies,ign timing is a bit out,but the hall sender bit on the side of the dizzy stopping me turning it enough,so i forced it and snapped the plastic bit that holds the wires,moved it so it`s running faster,so think that is now about right.
Promised the wife i would put her new carb on tomorrow,so not going to be able to spend time on it now,need to just move the vernier a bit see if it helps...Help i can`t take much more..Think i am going to have to take it off the road,but it`s summer

Got this up on cgti too,had a reply on there,and i think he may just be onto something !!

Here is my pipework,notice the blue T piece,from the manifold ,goes to idle stab valve (vac) I assume the vac passes through the idle valve ? and then goes back into the intake pipe before the throttle body.and the other side of the T piece goes too the rocker cover,now the original cover only had the 1 output,i bought this one as it was not rusty.




Going to remove the T piece,and connect the idle valve directly too the intake,using the clear pipe,and see if that makes a difference,now we are talking about 4 months here since i changed the rocker and put the catch tank in,why has it only just started causing this running bad issue ?
Possibly the valve is no longer getting enough vac,to make it work,hence why it won`t idle,possibly the one connection on the cover was blocked,me ragging it has cleared the blockage,and now it`s not supplying enough vac to the valve ?
Clutching at straws here guys,but think he may just be right.What is the pipe that comes out the back of the head ? Where the inlet manifold is,clear pipe between there and then joins too a T piece that the idle valve also joins too ?

Am starting to think that i should have pulled that pipe off there before i took off the head !!

He also put up this pic of his daughters early mk1 gti,notice there is no idle stab valve,but the pipe that connects,goes too rocker then air box...

Thanks for your help,everyone who took time out too read and comment ! [:D] It`s now fixed,running a little lumpy,but i need to get out and drive it before i start messing with the vernier,in an ocd style !
Can`t believe it didn`t occur to me to check that pipe ,before taking the head off etc.
But the upside now is i have a skimmed and ported head,with nicely lapped in valves,and got the Janspeed fitted.Get in !!!