Tappet screws hammered to death

I have noticed that the VWH tappet screws dont seem to last very long on my T1 1641 engine before developing flats and burrs where the valves hit the screws - two things are different about the engine.

1. Stainless valves
2. Replacement heads

It always seems to be No2 and No4 cylinder tappet screws go first - could it be that the valve guides are slightly further apart on the new heads than original?

Could I fix this with shims on the rocker arm assembly so the ends of the screws actually completely overlap the ends of the valves ?

Needless to say this makes tappet setup tricky because if you move the screws, the burrs make the gaps seem smaller than they really are.

 

Identical Auto Linea sold in genuine VW boxes at a higher price because they have VAG logos on the boxes.

Complete with casting flash on air fins, no hole for thermostat rod etc.

 

Swivel feet adjusters not an option?

 

I have heard that adjuster screws aren't that hot these days. But then I've also heard of swivel feet falling to pieces. Usual junk component story. You are aware that the screws hit the valve stem slightly off-centre, so that the valve effectively rotates in its seat?

My Autolineas bought about five years ago have been fine, in fact I'd say the castings were better than OE VW. Quite a lot of casting flash, but then VW were hardly blameless in this matter. I've just finished cleaning loads of flash off original two VW Beetle heads. Think of it as extra fin area ...

 

The rockers aren't part of the head so not sure where the head maker comes into this?
AA heads for the win BTW. Autolinear are a bit shoddy in comparrison.

 

Id've thought it was more to do with the relative rates of wear between the valve and the tappet (unless the tappets are striking at an odd angle).
Although it's a PIA I'd rather replace tappets once in a while than fit new valves.....good quality rollers or swivel feet may be worth trying....

have a word with John Maher....he's into all this technical malarkey

 

just use old original ones

 

I have heard a few times that people have had problems with non genuine ones getting chewed up

 

The screws are whatever VWH sell as good quality.

And definitely two of the screws 'miss' slightly and are more than just off centre, hanging over the side of the end of the stem by the thickness of an evil sharp burr, while the other two screws on the other cylinder actually land on the end of the valve stems squarely and so just develop flats..

And compared with new heads and valves the screws are pretty cheap and easy to replace.

I will look at the other possible adjuster designs, also I wonder about using lash caps to make the heads of the valve stems effectively slightly larger diameter, but then the screws will be hammering down at a steeper angle and probably develop even more distinct flats.

 

But your lash caps would be made by EMPI

 

...and therefore made of cheese?

 

Its simple things like this that make a man want to get rid

I have used a few made in china parts on my daily water cooled dub and had no problems
When it comes to aircooled nowt lasts

I did a bit more looking around the deep wardrobe that is google tonight and its a common problem with aftermarket screws
Id change them before the start dropping bits into the oil

 

Being Taiwanese, I think they're made out of tofu...