The Triumph Dolomite Club - Discussion Forum

hi Steve,

I've had several cars with SUs over the years with wrong tops on them, including my current 2" SUs when I got them (had one of each, and both should have been solid tops with no vent hole). A lot of people don't even realise that there are two types.

Simply unscrew each top and look just below the threads that the top screws into. If you see an obvious oblong hole about 1/16 " diameter, maybe a bit bigger, drilled downwards into the bell housing casing, then that carby needs a solid top. If there is no hole drilled downwards into the casing, then the carby needs a top with a vent hole in it.

It could be that you have two different carbys and all is OK, but I doubt it, although its a remote possibility. The only way is to have a look, dead easy and it only takes 5 minutes.

David

Hi David

Thanks for the quick response , definitely no internal vent in either housing,
So is it okay to drill a same DIA hole in the none vented cap , apart from this vent both damper rods are the same

Thanks Steve

Thanks for the info, going to check all that before ordering, can't get new needles til the 2nd Jan anyways, so I can have a good look round whilst waiting.

This the correct oil?

http://www.burlen.co.uk/partDetail.aspx?partID=45088

Steve, yes simply drill a hole of the same diameter in the pastic top.

The other thing I would do is buy new dashpot springs. From experience a lot of SUs have acquired the wrong springs, or often they've been stretched or cut down during the past 30 years as rumours of how to magically get more power have circulated around. All that usually happens is the mixture is stuffed when accelerating and the carbys are untuneable. Springs are about $10 each plus postage from Midel carbys, the SU specialists here in Australia who surprisingly export SU bits around the world. Google 'midel su' and you'll find them.

Saitrix, nope, not this one. Here's another trap; there's 2 types of SU oil!!! Dashpot oil for vintage cars with very old SUs (which is the one you've found), and the other is damper oil, which is the one you want. Type in the part name: damper oil SAE20 or part number BDR125SINGLE

cheers

David

awesome info, thanks david.

Thanks! Would have got the wrong one otherwise.