Carbs: SU-HS6 vs SU-HIF6
 

Hi All

Can anyone tell me what the pros and cons of the SU-HS6 and the SU-HIF6 are; how they compare as far a parts and servicing goes, performance wise and the level of difficulty of tuning the two and any special tools needed.

Just as a side thought, I personally think the HS6 is a far more aesthetically pleasing carb but I have a feeling the HIF6's are better performers.

Thanks for the input.

Dylan

Dylan,
The HIF6 were used on our US cars for only 1 year 1971, there were a great deal of teething problems at first but were much better at retaining the proper fuel mixture and power over a greater temperature range due to the Bi Metal jet holder.
The HS6 which needed constant adjustment were not good for controlling emission standards which were getting extremely harsh here in California , as emission standards increased power declined .
Mister T.

hif6
 

120 estate
b20
hif6
40mpg on a run.
previous twin hs6, set up on rolling road......20mpg

you probably get the picture!

Its not fair to compare worn carbs with nice new ones so the 20 - 40 mpg does not give much of an indication.

I would expect the HIF to give slightly better MPG (2% ish) and they do flow slightly better (HS6 210 CFM HIF6 240 CFM) so a small power increase could be expected.

My big dislike of the HS6 is the external pipe from the bowl to the jet that has a nasty habbit of leaking petrol onto the exhaust.

The problem you are likely to have is getting the HIF's to fit and work unless you are very lucky and find the correct ones.

Ciderman

Thanks for your input, you must have been digging around a bit cuz this thread is old! :)

Classic Swede

Are you sppeaking of HIF's that don't come off Volvo's being hard to fit?

Dylan

That it, If you were to take HIF off say a metro you would have to make linkages to get it to work. Apart from that there would be no issues provided you change needles and jet to work with your engine.

diggin it up again...
 

hi,

so, i'm looking to up my b18a to something with a bit more bite..

i manage to get a pair of HIF6's off a 142 in the US. before i start fitting, am i going the right way, or should i really be using HS6's? i take it the aluminium dual intake from a p1800 will accept the HIF6's ok?

are they as easy to tune? what about needles, etc..

Is that a standard inlet manifold or after m'kt?

Hi arcturus

Its the standard pre 66' aluminium manifold that was used with the single down pipe exhaust manifold he is talking about. What guys do is sever the intake side from the exhaust side on the twin down pipe/twin carb Siamese cast iron manifold and use the aluminium manifold with that. Only problem is that you have to skim the exhaust flange or make up some shims for the intake to fit because the two flanges are different thicknesses.

Dylan

HIF6 for sale
 

I have a set of HIF6 carbs for sale on ebay. I have decided to head another direction with the engine in my p1800 so these are up for grabs.
Ebay item number: 150569072234