A bit of an update on this thread.
So following the sage advice from this forum (many thanks guys) I made up an adjustment tool out of a spare Allan key and a strip of 2mm steel plate. To start with it looked just like the factory tool shown in the factory manuals.
Once the rear bulkhead panel and the window tunnel were removed, I undid the cam cover bolts (3 accessible from behind the seats and the last one through through the rear wheel arch) and withdrew the cam covers. I wanted to start on the LH cylinder bank first as this side has given me the most trouble.
I made a tappet bucket locking pin out of a short length of 7mm steel bar. This locked the inlet and exhaust tappets on cylinder #2 really nicely. Out with the feeler gauges and both the inlet and exhaust are reading 0.05mm below spec. I measured the inlet and exhaust clearance on cylinder #4 - same deal. So it was time to deploy my new adjustment tool!
I found that the adjustment is incredibly sensitive - about one hex flat to open up the clearance to the required specification. The only other issue was the rear cylinder in each bank, where the chassis rail restricts the movement of the lever. So I had to make some adjustments to the handle which made it difficult to get purchase on. After some choice words I finally managed to get the LH bank done. Now on to the RH cylinder bank, which due to the proximity of hoses, ignition coil and fuel pipes would be even less accessible than the other side. I took a deep breath and measured the valve clearances, which were all in-spec!
Greatly relieved and a little surprised, I changed the timing belts and refitted the cam covers. I think the reason the LH clearances were consistently incorrect is due to the head coming off on that side to change the leaking cam carrier gasket back in 2011. I fitted one of those new-fangled plastic gaskets instead of a paper one, and I guess it must be 0.05mm thinner than the paper type.
I also replaced the brand new, but rubbish quality distributor shaft O-ring seal, which has been leaking ever since I replaced it 6 months ago. I got it through a VW supplier as the bugs use the same Bosch distributor as Alfa. However, this time I bought seals from both Machine 7 (who supplied the last ones) and VW Heritage, who supposedly supply "good quality" Brazilian items. This time around it was Machine 7 who came good, supplying a pliable seal that was easy to fit and didn't have flash lines or other moulding imperfections. The "good quality" seals were made from the same hard plastic as the previous seals, with flash lines and other imperfections. They only cost a couple of quid so it was worth casting the net a bit wider. Still early days but after a few miles no leaks to report
The only thing I have noticed is that the carbs need re-tuning, which suggests my compressions may have come up on the (you guessed it) LH cylinder bank
So pretty much all set for Goodwood tomorrow, if the weather can make up its mind!
Lauren