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 Posted: May 2, 2017 05:25AM
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CA
I went to twin HS4 on my relatively stock 1275 AA engine.

They work very well indeed.  ( #5 needle )

 

"Everybody should own a MINI at some point, or you are incomplete as a human being" - James May

"WET COOPER", Partsguy1 (Terry Snell of Penticton BC ) - Could you send the money for the unpaid parts and court fees.
Ordered so by a Judge

 

 

 

 Posted: May 1, 2017 06:32AM
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US
Ian send me your email or snail mail address.

 Posted: Apr 30, 2017 08:14PM
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That would be interesting .. any chance of a (partial scan??

One reason for the H4s status is its links to the Works cars.  In the day, many event regulations required the use of the homologated manifold ..while allowing free choice of carbs..  H4s with their vertical mounting holes could be used with the "standard" Cooper manifolds...  Paddy Hopkirk even developed a special carb that was basically a DCOE with a bit cast on to allow fitting to the standard SU manifold..... which met the letter of the law..

For those not restricted by homologation rules Special Tuning sold twin HS4 kits as bolt on items for the Mini.

Did Keith point out any actual performance issues when making a choice???

Cheers, Ian

 Posted: Apr 30, 2017 06:55PM
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US
Quote:
Originally Posted by malsal
Quote:
Originally Posted by dogscarf
Fellow Minioids,  I have two Mini Cooper S's a 1967 and 68.  I want to go up from the two 1.25 to two 1.5 SU and try it out.

 Question:  I have many SU HS4 carbs lying around so why couldn't I just use two of those from an 1962 Austin Healey 3000?  They do have offset mounting flanges.  I noticed that the H4 has two parallel mounting holes on the flange.  They also have a convoluted brass choke arm.  I was on another Mini forum and they turned up their nosed at the HS4 carbs.  Is this legitimate?  Is their a significant difference.  They appear much the same to me.

Dogscarf
There is a thread on the board where someone in TN (Ed) was experimenting with different set ups on his 1275 S and tried 1.5 inch carbs and they produced less HP than the stock HS2's, he ended up refitting the HS2's.
In the June 2017 issue of Mini Magazine the question of differences between the H4 and HS4 are answered by Keith Calver.  So see page 88 where he says "Many consider the H4s to be the Holy Grail of SUs for the Mini".

 Posted: Jan 29, 2017 02:02PM
 Edited:  Jan 29, 2017 02:03PM
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Quote:
Originally Posted by malsal
Gotcha. For some reason i thought you were talking from a UK perspective.
Hi Mal, probably not an unreasonable presumption... Both my (active) cars are UK built and I did live there for a while so I guess some posts have a northern hemisphere perspective.

I shall have to be less cryptic in future.

Cheers, Ian

 Posted: Jan 29, 2017 08:24AM
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Gotcha. For some reason i thought you were talking from a UK perspective.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jan 29, 2017 12:00AM
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Quote:
Originally Posted by malsal
Thanks Ian, i think you could still get an 850 in a van or pick up a lot later than that. I have a late pick up/van brochure somewhere with the options i will take a look for it.
When I said "we" I meant those of us in the Great South Land...  we didn't ever get the Pickup - except for a few private imports.  Because of the small (relatively) production quantities I think BMC actively rationalised product lineups.  Once the volume item (the sedan) moved to a 998 engine in '65 that was then standardised across the range (which only consisted of the sedan and van anyway)... along with its HS2 carb...

Cheers, Ian

 Posted: Jan 28, 2017 09:27PM
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GB
It would probably have been an HIF4 with the diagonal flange, not a square flanged 38 which was later.

I think the carb swapped over in '75/6 when the rubber subframes came in and the bulkhead crossmember gained a bigger dip to better clear the bottom of the jet.

 Posted: Jan 28, 2017 02:12PM
jeg
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Many 850's had HS4 from the factory, and some Chilean market 850's also had HIF38.

Dogscarf, did you check out the ST publication - AKD-5096 ?

It might have the info you need -

The peasants are revolting...          

"Gone with the Wind" - a brief yet moving vignette concerning lactose intolerance

 Posted: Jan 27, 2017 10:33PM
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We still had 1.25 single SU on 1100 up to 75.

 Posted: Jan 27, 2017 02:31PM
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Thanks Ian, i think you could still get an 850 in a van or pick up a lot later than that. I have a late pick up/van brochure somewhere with the options i will take a look for it.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jan 27, 2017 01:48PM
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We moved on from 850s to 998s in 1965... I'm pretty sure these still came with HS2s (apart from the .Matic).

Cheers, Ian

 Posted: Jan 27, 2017 09:31AM
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Quote:
Originally Posted by 1963SV2
Quote:
Originally Posted by Alex
The air velocity through a smaller carb is higher for a given volume than with a larger orifice, which has many performance gains. It's only when you start reaching the limit of the flow capabilities of the smaller carbs that you'll get a noticeable gain (in some areas) by going up a size. Yes, it is a variable venturi, but that is more advantageous for mixture control.
This may be theoretically arguable... but it is interesting to note that when BMC looked for a few more HP to offset the .matics auto box they fitted the bigger carb....

cheers, ian
Ian, wasn't that the same time that all the Mini range got HS4's ? Or was it just the 998's that got the HS4's, did the 848's stay with the HS2's until they were phased out ?

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jan 27, 2017 04:13AM
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Quote:
Originally Posted by Alex
The air velocity through a smaller carb is higher for a given volume than with a larger orifice, which has many performance gains. It's only when you start reaching the limit of the flow capabilities of the smaller carbs that you'll get a noticeable gain (in some areas) by going up a size. Yes, it is a variable venturi, but that is more advantageous for mixture control.
This may be theoretically arguable... but it is interesting to note that when BMC looked for a few more HP to offset the .matics auto box they fitted the bigger carb....

cheers, ian

 Posted: Jan 26, 2017 10:11PM
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Police cooper s used twin HS4 on their cars here as part of their specs when ordering cars, I have them on my ute which has 95HP at the engine CP4 needles and red springs goes real well , but it probably needs this upgraded HP to use them properly.

 Posted: Jan 26, 2017 02:57PM
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GB
The air velocity through a smaller carb is higher for a given volume than with a larger orifice, which has many performance gains. It's only when you start reaching the limit of the flow capabilities of the smaller carbs that you'll get a noticeable gain (in some areas) by going up a size.

Yes, it is a variable venturi, but that is more advantageous for mixture control.

 Posted: Jan 26, 2017 01:52PM
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"..... I can see that the engine may operate better with smaller carbs keeping the inlet gas velocity high..."

Except that SU are variable venturi carbs so at less than full throttle the velocity will be the same irrespective of the carb size.....

"...Seems like there have been a lot of tuners who've tried a pair of HS4s, only to either go back to a pair of HS2s (or a single HS6/HIF44)..."

Not a lot of logic here.... (unless they're maybe looking for max economy)..if  larger carb doesn't work (which is somewhat illogical in itself..) why would you go to an even larger one (i.e. the HS6)????

But of course there's always lots of "It depends..."

Cheers, Ian

 Posted: Jan 26, 2017 10:25AM
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OK,  Great.  Lots of useful info.  I can see that the engine may operate better with smaller carbs keeping the inlet gas velocity high.  I was mis-informed that the H4 carbs were better.  Luckily I have several HS4 carbs and they are easier to find.  I just need to rebuild them now and put in new bushings and throttle shafts.  I have extra manifolds to, so I can swap and go back to the H2 carbs.

Dogscarf

 Posted: Jan 26, 2017 09:26AM
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A pair of 1.5s flow more air, but if the engine can't use that the result tends to be only useful at WOT.

Seems like there have been a lot of tuners who've tried a pair of HS4s, only to either go back to a pair of HS2s (or a single HS6/HIF44).

 Posted: Jan 26, 2017 08:09AM
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Quote:
Originally Posted by dogscarf
Fellow Minioids,  I have two Mini Cooper S's a 1967 and 68.  I want to go up from the two 1.25 to two 1.5 SU and try it out.

 Question:  I have many SU HS4 carbs lying around so why couldn't I just use two of those from an 1962 Austin Healey 3000?  They do have offset mounting flanges.  I noticed that the H4 has two parallel mounting holes on the flange.  They also have a convoluted brass choke arm.  I was on another Mini forum and they turned up their nosed at the HS4 carbs.  Is this legitimate?  Is their a significant difference.  They appear much the same to me.

Dogscarf
There is a thread on the board where someone in TN (Ed) was experimenting with different set ups on his 1275 S and tried 1.5 inch carbs and they produced less HP than the stock HS2's, he ended up refitting the HS2's.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

Found 23 Messages

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