Damaged Head, is it Fixable.

[Andy]

Last time I ran my car on the strip I managed to do some damage, I have just stripped the head off to see what it was.

The engine is a 2110 with a K8 the heads are CB 044s 40x 35.5 with CB dual springs. It has covered around 6000 miles
 


The first thing I could see is the inlet valves seem to be pulling through the retainers, the right hand one seems worse but both look like they have problems.





A piece of the valve seat appears to have broken off and has been hit by the piston into the head.



You can see the seat minus the chunk.

So the question is do you think the head is repairable who could put a new valve seat in and secondly what could have caused it, I was running at drag day probably did about six runs, two with the belt off before this happened. Could it be over revving I did see 7000rpm on one run or what about running with no belt.

Also could the piece of the valve seat being squashed by the piston into the head, damage the rod or crank.

[dyno don]

  Andy my man you should be ok with a new seat replacement, new valve, and valve job. Your piston dome can take alot of punishment and dont think you need to tear down any further. Check your guide wear and this can be done by your head wiz when the work is being performed. Dont think because the belt was off that it was the problem either. The existing seat doesnt look to bad as for your concern about excessive RPM.  you could do a leak down test after all said and done to check your ring seating.  As to what caused this condition? perhaps a seat anomoly is the only culprit. Either way...not a big deal from what I see.  Get'er done and go back out and beat it to death.  Hope this helps... good luck, Dyno

[Andy]

Thanks for taking the time to reply Dyno. That is better news than I was expecting to hear.

[dyno don]

  Dont reach for that beer just yet Andy/although tempting....  Check both heads,springs,retainers,seats,valve tops and keeper grooves,and make a determination as to overall condition of things. The cam in question is good for 7500 set up properly with all the valvetrain goodness. Seats can take a lot of punishment unless the retainers dont support the springs and or the springs fatigue creating valve float and begin to bounce off the seat with harmonics. Flat edge check the tops of your valves and look for any differences as this is easy and will  give you some idea to the valve geometry as they sit and wait to be freshened up. If all look ok then >> grab that beer and enjoy..!!   Peace out/Dyno     ps, with your heads off I suggest for you to index  your spark plugs by using washers to turn the plug around from where it is and to point into the chambers(towards the intake) and not away from them allowing for a cleaner burn.

[Udo]

As don sayed , no problem to fix it ...

Udo

[Andy]

I had a quick look at the valve stems today, resting a straight edge on the exhaust valves, the inlet valve with the damaged seat has a gap of 0.2mm and the other inlet which was pulling through the retainer had a gap of 0.3mm.  for this head it looks like both inlet valves need replacing along with the collets, retainers and valve springs for good measure.

Is replacing the seat, a job for a VW specialist or could it be done by a general auto engineering workshop.

To repair the damage to the Aluminium surface is it acceptable to just smooth out any sharp edges or do they need to be welded, to fill the pits.

And does anyone know where I can buy the CB valves in the UK

Thanks

[dyno don]

 Hi Andy, It would be advisable to have the critical area welded and the others areas can be smoothed out with little effort. I would recommend also to have all the seats double checked due to the many variables of heat sinking which some heads do better than others expecially non factory vw cylinder heads. The heads are worth every penny to keep but would invest quality time to insure some more longevity from them. My choice would be to replace as necessary(budget) or go full on and replace all with quality replacement seats,valves,and hardware, and start fresh with a set of heads that have been road tested and "cured" for your 6000 miles of travel. If in fact your indicating that the  retainers are showing signs of fatigue then rethink your valve geometry closely and be sure that spring shims are used under the springs so as not to gall the heads and in the process losing some geometry. Perhaps you can lighten things up as well with a good set of titanium retainers followed by some good quality HD aluminum pushrods (example:smith bros.in oregon,U.S./or, aircooled.net) or perhaps someone else can pipe in with another quality source. These two things alone can help you in the future in achieving a longer valetrain life and a quiet one as well. When you split the case get some UDO light weight lifters or some  Jp's?  Good Luck, Dyno

[Andy]

Hi Dyno, it'll have to be a budget fix for now, I'll get sourcing the parts.

I'll bear in mind the lighter set up for the future, at the moment I have Udo's standard lifters and cro mo pushrods.

Thanks for taking the time to help.

Andy.