Right-o Pillar Drill turned up. Pulled the old unions out eventually. A bit of head scratching how I hold a carb top in the right position to drill straight. I made a holder in timber and used the airfilter fixings inserted into the timber and then held in a vice. Seemed to do the trick.
Smaller Return union was m8x1.0 and I turned down the 0.7mm jet and drilled out the top of the union and screwed it in as Webcon man said to do. The second Feed union, as I was told, and a quick look with pitch gauge I thought it was m10x 1.0. So drilled and tapped away, only to find out it was in fact 0.9 pitch which is a pitch that carb companies sometimes use. Ordered the right thread 1.0x 8mm Feed union. Its is a little short really but will test tomorrow and hopefully okay for a 20 min journey to Brooklands on Sunday. If is rubbish I can order some better item I have now found at Eurocarbs. Fingers crossed this has worked.
Everything super sealed everything with blue paper and masking tape before I started drilling, and super cleaned out after with brake cleaner. Then fuel union/s threads sealed up with Loctite 542 as I was recommended. Test tomorrow.
PS a 4.5mm drill bit fits in the filter housing supply to the float needle (again Webcon man recommendation)
