Hi Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
twigworker
Jedi Trainee
Offline
I just watched a set of SU clones go off on ebay. In one of the questions to the seller an outfit in the UK was mentioned and I visited their site.
https://www.burlen.co.uk/partList.aspx?carbID=15847
was the page on the Burlen site that was devoted to MGBs circa 1972. On that page there were four carb types referenced for 1972 MGBs. In the order as they were presented was, HIF4 presented as an AUD434T set, HS4 presented as an AUD492T set, HIF4 presented as an AUD493T set and HIF4 presented as an AUD550T set. Obviously the HS4 is the side mounted float chamber model and the HIF4 has the float chamber built into the bottoms of the carb body. The year indicators were 72-72, 72-72, 72-72 and 72-74 respectively. Setting aside the HS4 unit, the three HIF4 carbs were very similar, springs, damper plungers and jets. The only differences that I could see were the needles and throttle discs. All discs had spring loaded relief valves but the first set listed used part number WZX1323 and the other two used number WZX1329. The first two HIF4 carbs listed used AAU needles and the third used a needle numbered ABD. I may have overlooked some other non-shared parts but I don't think that there were any. The third HIF4 carb listed as being applicable from 1972 thru 1974 differed in needle use, AAU vs ABD. I was drawn to the 1972 applications simply because I own a '72 roadster but in looking at these specs some questions came to mind. Why were there three different carburetors specified for this '72 model? Why would there be two different designations for seemingly identical carbs? What would be the performance difference between the AAU and ABD needles? In my experience I have never noticed a difference in the relief valves in throttle discs equipped with them. Is there a difference and if so what is its nature? All of this perhaps should be tossed into the "useless information bin" but if anyone on the list can answer any of these questions I would be eager to listen. Thanks, Jack
https://www.burlen.co.uk/partList.aspx?carbID=15847
was the page on the Burlen site that was devoted to MGBs circa 1972. On that page there were four carb types referenced for 1972 MGBs. In the order as they were presented was, HIF4 presented as an AUD434T set, HS4 presented as an AUD492T set, HIF4 presented as an AUD493T set and HIF4 presented as an AUD550T set. Obviously the HS4 is the side mounted float chamber model and the HIF4 has the float chamber built into the bottoms of the carb body. The year indicators were 72-72, 72-72, 72-72 and 72-74 respectively. Setting aside the HS4 unit, the three HIF4 carbs were very similar, springs, damper plungers and jets. The only differences that I could see were the needles and throttle discs. All discs had spring loaded relief valves but the first set listed used part number WZX1323 and the other two used number WZX1329. The first two HIF4 carbs listed used AAU needles and the third used a needle numbered ABD. I may have overlooked some other non-shared parts but I don't think that there were any. The third HIF4 carb listed as being applicable from 1972 thru 1974 differed in needle use, AAU vs ABD. I was drawn to the 1972 applications simply because I own a '72 roadster but in looking at these specs some questions came to mind. Why were there three different carburetors specified for this '72 model? Why would there be two different designations for seemingly identical carbs? What would be the performance difference between the AAU and ABD needles? In my experience I have never noticed a difference in the relief valves in throttle discs equipped with them. Is there a difference and if so what is its nature? All of this perhaps should be tossed into the "useless information bin" but if anyone on the list can answer any of these questions I would be eager to listen. Thanks, Jack
