MK2 16V past 4000rpm?

I have heard that when you get past 4000rpm in a valver, then that's where the extra 8 valves come into play compared to an 8 valve that is!, but what is supposed to happen?

Do the revs just keep climbing solid, the same speed past 4000rpm

or should the revs fly once past 4000rpm?
Edited by: gti_kev

 

16 valves are working constantly, it's not like a V-Tec (on a motorbike).

But that's where it goes "on cam" so they say. The revs just keep climbing and when you look at your speedo before you know it you're up to 90 in 3rd!!

16 valves rock!!

 

Cheers mate, so it does rev faster past 4000rpm just keeps steadily rising then?

Because that's what mine does!

 

On a KR you should notice a kick over 4000rpm, should feel flat under 4k,then 'lively' over 4k.. If not, your cam timing is most likely out after a cam belt change.
Edited by: GVK

 

ooo, is that the timing on the dizzy, 6-7 deg BTDC aint it?

 

CAM timing

(the relation between exhaust cam and crankshaft)
Edited by: GVK

 

So the cam belt may be a knotch or 2 out then?

Is this a garge only job, as the strope is just for the the static timming (dizzy) yes?

 

Have you ever had a cam belt fitted since you've owned the car?

 

Yes, I had that and the tensioner replaced about 10 months ago, seems to run fine, so i never bothered to have it double checked!

How do you check it is fine?
Edited by: gti_kev

 

It will run fine, just a lack of power.

Unless you're confident in timing and tensioning a cam belt I would leave it to someone who does.

What tends to happen on a 16v in my experience is you set up the crank on TDC and then when you tension the belt it pulls the crank round,putting it out of time.

What I do is turn the crank back a tooth or two, then tension the belt,this pull the crank round on time.

Also, never rely on the timing marks on the bottom pulley, the vibration damper can twist out of shape giving an incorrect TDC reference, either use the marks on the flywheel or by inserting a long thin screwdriver down number 1 spark plug hole, find TDC by turning engine clockwise to the point where the piston is neither going up or down.

Cam is easier to time as there's a notch in the cam pulley and an arrowed cut out in the cam cover.

 

Cheers, i'll go and get it checked!

 

Loving the new sig Gary

 

Just give it a good thrashing and she does respond more after 4000rpm, so things are looking ok, in fact, from 3500rpm - 4000rpm is like step one a bit of a kick, and then lets loose after 4000rpm