Tuning/Fitting a 1 1/2 HS4 SU Carburettor

Post by **Pikey** » Wed Jul 18, 2007 8:05 am

Ive managed to get hold of a complete HS4 carb and manifold from a X reg Mini in a breakers yard. My only problem is that it has a small breather pipe about 3/8"? exiting the venturi. Im assuming this must have connected to the timing chain cover on the mini, but on my 1971 Pickup Ive just got the Rocker cover pipe which is a different diametre. Should I and how do I connect these two breather pipes. Also what needle should I run it with (sprung type). Ive got the standard 12g202 head on a 1098cc (overbored 30 thou) and K&N filter.

Post by **Shawn** » Wed Jul 18, 2007 8:11 am

I've got mine plumbed to the rocker cover. The short brass breather on the carb often had a plastic spacer fitted which increased it's diameter to about 1/2", the same as the rocker cover tube.

Post by **bmcecosse** » Wed Jul 18, 2007 9:41 pm

Yes - connect it to the rocker cover breather - use tubes that fit. the Mini needle will be near enough to at least get the car going. After that you can decide from the spark plugs if it's rich/weak or just right!

Post by **RogerRust** » Fri Jul 20, 2007 3:41 pm

In the end we settled for an AAU needle Please see my post in General Discussion.