HS6 Carb question

red122 · Mar 14th, 2020, 22:15

I have an old set of twin carbs and a later type with the floating springed needles .
Does anyone know if the pistons are interchangeable ? Can I fit the sprung type in their piston into a non sprung type carb body ? sorry if this is a bit hard to follow just they are a lot easier to centralise ..

Ron Kwas · Mar 15th, 2020, 08:34

R122;

The term "old" is relative, and doesn't convey what I would need to know...I was under the impression that earlier HSs (denoted by FuelBowl on the side, see pix!) had non-spring Metering Needles, and later HIF (Horizontal Integral Float) were equipped with "self-centering" spring MNs...which type are you speaking of?

Source: https://www.sw-em.com/su_carbs.htm#R...ce_Information

To answer the question as best I can, Dashpots are certainly interchangeable HS to HS, and HIF to HIF...they were precision machined and paired with the Bell at manufacture to meet the 5-7Sec rule (and possibly/probably other fit checks) but as a rule should not be mixed and matched without a very careful fit-check. For this reason, I would say to interchange Dashpots between the HS and HIF versions, a even more careful, critical and precise fit-check (most importantly MN position in Jet) would have to be performed when attempting this...I've never attempted it (for fear of missing something critical in these precision assemblies!)...I have also never felt the need to install a spring MN into an HS Dashpot...

Ref: https://www.sw-em.com/su_carbs.htm

Cheers

Derek UK · Mar 15th, 2020, 08:54

See last post on this thread. https://www.volvoforums.org.uk/showt...=275740&page=3

Best to give Burlen a ring. Not sure why you want to use the bias sprung needles but I suspect they will say stick to the fixed ones.

Mar 14th, 2020, 22:15	#1
red122 Master Member Last Online: Apr 21st, 2024 13:47 Join Date: Jun 2007 Location: tunbridge wells	HS6 Carb question I have an old set of twin carbs and a later type with the floating springed needles . Does anyone know if the pistons are interchangeable ? Can I fit the sprung type in their piston into a non sprung type carb body ? sorry if this is a bit hard to follow just they are a lot easier to centralise ..

Mar 15th, 2020, 08:34	#2
Ron Kwas Premier Member Last Online: Today 13:22 Join Date: Jul 2007 Location: Connecticut, USA	R122; The term "old" is relative, and doesn't convey what I would need to know...I was under the impression that earlier HSs (denoted by FuelBowl on the side, see pix!) had non-spring Metering Needles, and later HIF (Horizontal Integral Float) were equipped with "self-centering" spring MNs...which type are you speaking of? Source: https://www.sw-em.com/su_carbs.htm#R...ce_Information To answer the question as best I can, Dashpots are certainly interchangeable HS to HS, and HIF to HIF...they were precision machined and paired with the Bell at manufacture to meet the 5-7Sec rule (and possibly/probably other fit checks) but as a rule should not be mixed and matched without a very careful fit-check. For this reason, I would say to interchange Dashpots between the HS and HIF versions, a even more careful, critical and precise fit-check (most importantly MN position in Jet) would have to be performed when attempting this...I've never attempted it (for fear of missing something critical in these precision assemblies!)...I have also never felt the need to install a spring MN into an HS Dashpot... Ref: https://www.sw-em.com/su_carbs.htm Cheers

Mar 15th, 2020, 08:54	#3
Derek UK VOC Member Last Online: Today 14:24 Join Date: Jul 2006 Location: Chatham	See last post on this thread. https://www.volvoforums.org.uk/showt...=275740&page=3 Best to give Burlen a ring. Not sure why you want to use the bias sprung needles but I suspect they will say stick to the fixed ones.

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