Twin SUs or Weber 45 DCOE?

[evonaut]

out of interest, seeing as there a lot of opinions about what is a good set up and not, any views on this set up......

i have twin HS4s on my 1275 cooper s engine, they came with the car when i bought her in the 80s, the engine has been bored +0.040 to 1310cc, and I elected to use an SW5 cam instead of the 731 originally in the car, mainly for drivability in and around london which is where i live. i have a standard crank, 12G940 11 stud big bore head, and standard forged rockers etc.....

be gentle with me, please ;o)

evonaut

[rich@minispares.com]

out of interest, seeing as there a lot of opinions about what is a good set up and not, any views on this set up......

i have twin HS4s on my 1275 cooper s engine, they came with the car when i bought her in the 80s, the engine has been bored +0.040 to 1310cc, and I elected to use an SW5 cam instead of the 731 originally in the car, mainly for drivability in and around london which is where i live. i have a standard crank, 12G940 11 stud big bore head, and standard forged rockers etc.....

be gentle with me, please ;o)

evonaut

I think that twin hs2 would be a better carb for town driving with a 'soft' cam, the twin hs4 are more for hard driving where the engine would benefit from the extra air/fuel at top end

I think you would get a little more mpg and much more low speed flexibility with the hs2.


just keep the hs4 on the shelf 'just in case'

[evonaut]

thank you rich.

unfortunately i am not in a position to purchase a set of HS2s so will have to tolerate the lower mpg...... i will however ensure that the car gets a decent run out every now and again to take advantage at higher revs!

[rich@minispares.com]

thank you rich.

unfortunately i am not in a position to purchase a set of HS2s so will have to tolerate the lower mpg...... i will however ensure that the car gets a decent run out every now and again to take advantage at higher revs!

sounds like a plan!

[Spider]

thank you rich.

unfortunately i am not in a position to purchase a set of HS2s so will have to tolerate the lower mpg...... i will however ensure that the car gets a decent run out every now and again to take advantage at higher revs!

Find someone who has a set of twin HS2's and wants to swap

[mikep]

Twin HS4s are equally stupid on that spec.

I'm with Vegard on this one. A pair of twin HS4s would be better matched with a longer profile cam with more valve lift, as the real benefits only kick in at high rpm.

The OP's engine spec is a good tractable fast road unit.

I would recommend sticking with a single HS4, fully vizardised inside, with K&N filter (pref not cone) and good stub stack (not rubbish cheap one from ebay). And spend the money on a good flowing inlet manifold similar to Oselli Torquemaster, getting flow from good shape not large ports.

With this set-up you won't be giving away many horses as compared to twin HS4s or Weber.

If going to a single would be better of with HIF6 on a metro inlet, they are cheap and work very well. Not very sexy but solves the problem. Another idea may be to try and find a good 11/2 fish carb never ran one on a big engine but were second to none on small blocks.

[evonaut]

nice idea, and in fact my late father had a pair of HS2s ready to fit, can't find them anywhere - have searched my mums house high and low!

gonna give the HS4s a go........will just have to keep the revs up a bit