10 replies to this topic

[Patriot]

Hi,

Does anyone have experience of running twin HS2 carbs on a 1310 cc engine.

Would they be suitable or does it have to be twin HS4 or HIF44.

Many Thanks.

[jpw1275]

hs2's are too small really... you would be better using hs4's or a hif44 carb.... im using hs4's on my 1275

cheers james

[pdaykin]

A lot will depend upon the spec of your engine

[bluemini1979]

I had twin hs2's on a 1310 and it felt very restricted I changed them to twin hif4 from the mgb (twin 1"1/2) and its feels a load better throttle response and power delivery feels much better

[carbon]

With the twin HS2s being standard fitting on the 1275 Cooper S throughout production it is fairly safe to take them as being well suited to a 1275, 1293, 1310 or 1330 motor with up to 75bhp at flywheel. The other advantage of running HS2s is that the needle and spring combinations are pretty well documented.

 

Twin HS2s may be getting restrictive if you are planning on over 80bhp at flywheel, but this can be remedied by applying the 'Vizard' mods to the carb body and the throttle shaft.

 

In terms of limitations, there are hillclimb 1380's out there running 286 cams and still on HS2s, probably with over 100bhp at flywheel. Not using the standard BMC manifold through...

[MrBounce]

I had twin 1 1/4s on my 1301. I had a 266 cam and an MED Road/Comp head. Lovely tractable, torquey engine. not massive power (80-odd brake) but certainly lively enough. I don't think I would've been able to get much more out of it with that set up but it worked well with what I had

[Dusky]

With the twin HS2s being standard fitting on the 1275 Cooper S throughout production it is fairly safe to take them as being well suited to a 1275, 1293, 1310 or 1330 motor with up to 75bhp at flywheel. The other advantage of running HS2s is that the needle and spring combinations are pretty well documented.

 

Twin HS2s may be getting restrictive if you are planning on over 80bhp at flywheel, but this can be remedied by applying the 'Vizard' mods to the carb body and the throttle shaft.

 

In terms of limitations, there are hillclimb 1380's out there running 286 cams and still on HS2s, probably with over 100bhp at flywheel. Not using the standard BMC manifold through...

Does vizard do alot of mods to the carbs? And is it easy to diy?

Do you know what the mods are?

 

grtz and thanks in advance!

[Cooperman]

Twin HS2's are OK for engines with some serious power so long as the carbs are gas-flowed and the manifold is better than the original standard BMC alloy one.

The Group 1 race & rally cars were only allowed twin HS2's and with blueprinted engines they were putting out over 80 bhp.

At really high revs HS2's may struggle to breathe enough, but for a road car they should be fine.

Of course, a pair of HS4's will give a better top end on high-revving units with 'hot' cams and big valve heads.

[ACDodd]

I have engines specced by me running around the 100hp mark on standard hs2 carbs, it can be done! Your 1310 will be fine.

AC

[Patriot]

Many thanks all for information.

[carbon]

 

With the twin HS2s being standard fitting on the 1275 Cooper S throughout production it is fairly safe to take them as being well suited to a 1275, 1293, 1310 or 1330 motor with up to 75bhp at flywheel. The other advantage of running HS2s is that the needle and spring combinations are pretty well documented.

 

Twin HS2s may be getting restrictive if you are planning on over 80bhp at flywheel, but this can be remedied by applying the 'Vizard' mods to the carb body and the throttle shaft.

 

In terms of limitations, there are hillclimb 1380's out there running 286 cams and still on HS2s, probably with over 100bhp at flywheel. Not using the standard BMC manifold through...

Does vizard do alot of mods to the carbs? And is it easy to diy?

Do you know what the mods are?

 

grtz and thanks in advance!

 

The details for the SU modifications are very well detailed in David Vizards 'Tuning BL's A-series Engine'. In the blue jacket version of the book this is on pages 105 to 113. No special tools required but takes quite a bit of time if you're doing it properly...