Lapping in new valves.

[LowlifeDubber]

Soooo i took the missus car out thursday morning and came home on one of these.



Problem being a snapped cambelt.(New belt and tensioners replaced in september btw)

Anyway heres the outcome of that!








Anyway i decided rather than get a used head(£350) i would rebuild this one so i bought new valves,top end gasket kit,stretch bolts etc.

The guides are all fine so thats all good.

Its a long time since i lapped new valves in (last car was a 350 small block chevy) now i tend to use a drill attachment with a rubber hose on the stem end and ive so far done 2 exhaust and 2 inlet.

Im just wondering if the new valves are stupidly hardened?As ive read plently of conflicting advice on the tinterweb about how long to grind them in on vw's?
I know the principal behind it and ive got a decent 1mm grey line on all 4 valves by lapping them 10 mins with course and 15 mins with fine but just wondered if anyone had any experience lapping in NEW vw valves?

Car is a 1.6 16v AZD lump.

....and no she wont let me put a 1.8t in it 

[Seanl]

Holy sh!t! Not good! 

On the plus side, at least you know what your doing and what to do to fix it! 

[LowlifeDubber]

Yeah that helps a little otherwise i would have just bought another car with todays labour costs lol

[Chris.]

Bloody hell!

[danny_p]

That sounds like a long time to lap some valves in, as long as you get a good seat finish without resessing the valves all is good in theory,

I normaly drop a seat cutter onto the valves now to clean the seats up then put the valves on grinding machene  so if get you settings right they seat in less than a minute with fine paste,
May be worth haveing a look to see if you new valves have been ground to the right angels for the seat 10mins is a liy with coarse paste shouls still be abvel to finush off with fine in a minute or so,

Your grinding paste chould allways be naff

[LowlifeDubber]

Pleased you answered
The paste is about 20 years old tbh proper oldskool tin with coarse one end and fine the other.
Will go grab some over the weekend.
So your thinking 10 mins coarse and finish off with fine?
One thing I did notice on the exhaust side is the 2 valve seats  per pot are slightly different angles to one another before I even start. This is exactly the same across the head.
The valves sit about .5-1.0mm proud on one side before and after the valves have been lapped.
Inlets are fine though 

[DOA]

That really does sound like a long time to lap them in! Last set I did by hand (106 Gti) took less than 5 minutes each, coarse and fine. On the sitting proud front, are you certain that you have the correct valves for the engine or that there isnt supposed to be 2 different seat shapes on the exhaust side? Does sound a bit odd that the seats are different and you have different protrusions but I dont know enough about the engine to comment further. I kind of thought all the Mk4 engines were 20v jobbies lol.

[danny_p]

would hope to have them done quicker than 10 a valve form start to finish  tbh.

if you don't lift the valve often enough whilst grinding it to move the paste about mins it can take ages  so chould also be technique,  to some engines do have bloody hard seats.   never lapped the valves on a mk4 16v motor so cant say to be 100% sure,  but there are going to be quite hard probaly harder than those on a yank v8,  haveing a look at the seat before you start may gives a clue the smaller the shiney band where the valve seated  the harder the valve and seat are likely to be.

some engines have seats at diffrent angels have even met valves at diffrent angels would have thought thats unlikely tho

[LowlifeDubber]

Cheers lads.

Danny I think you may be right on the technique mate,im hardly popping the valve while im grinding so im gunna chuck the drill out the window and go oldskool with me stick,the seats seem stupidly hard and your right about the thin grind mark on the seat from the previous valves.
Deffo harder than the v8s ive previously worked on!

I will probably whip my head to work today and get a few more done.
On the upside ive popped the plug in the one pot ive done and poured fuel in the top and even with no springs in there is no leakage so they must be sealed well enough.