52 replies to this topic

[jamiestevenbell]

thanks for that if the balancing tube doesnt really help would it be good if i was to have 2 short bits made up to go from head to manifold, just not linked?

[Cooperman]

Well, mine came from my great friend in Los Angeles who bought them from an MGA guy and then modified them as spares for his 1071 rally 'S'. However, he damaged a head so I sent him out a replacement head and he sent me the carbs ready to fit my 'S' as a straight swap.

[jamiestevenbell]

so if i brought non mga hif4s i should be alrite

[jamiestevenbell]

oh rite i miss read it but thanks and does anyone know the ansew to this? cheers

thanks for that if the balancing tube doesnt really help would it be good if i was to have 2 short bits made up to go from head to manifold, just not linked?

[Cooperman]

You can't modify the float chamber on a H4, if you try heating and twisting the alloy it only breaks. The only option is to rebuild with the correct parts, in which case they are no longer MGA carbs............

I don't know why you feel the need to be taking a 'pop' at me. I said they CAME OFF AN MGA AND WERE MODIFIED TO FIT A MINI. Let me repeat, they CAME OFF of an MGA.
First you have a go at me for explaining how do do a calculation to establish gearing comparisons with different wheels and tyres, telling me I'm wrong and now you get pedantic about this as well. Do you really think I don't know about float chamber angles on a Mini?
Did I do something to offend you. If I did then please tell me what.

[bmcecosse]

My view - stick with the HIF 44 - and Vizardise the throttle plate etc etc. It will be better than twin 1.5" SUs. Remember - each cylinder breathes independently - there is no worthwhile crossflow, in fact - the balance pipe disrupts flow - so a good single carb inlet manifold (with no water heating) will allow each cylinder to see a 44mm hole - instead of a 38mm hole in ONE of the twins. It will never see the hole in the other carb.

[Cooperman]

I don't know why you feel the need to be taking a 'pop' at me. I said they CAME OFF AN MGA AND WERE MODIFIED TO FIT A MINI. Let me repeat, they CAME OFF of an MGA.
First you have a go at me for explaining how do do a calculation to establish gearing comparisons with different wheels and tyres, telling me I'm wrong and now you get pedantic about this as well. Do you really think I don't know about float chamber angles on a Mini?
Did I do something to offend you. If I did then please tell me what.

LOL what makes you think I was having a go at you, all I'm doing is offering the benefit of my experience. If some not so knowledgeable person on this forum wastes there money buying a set of MGA carbs. Then found that they had wasted there money, would you not feel bad about that ? I certainly would if I had said they'd work................

Please re-read what I said and don't be silly. I said:

...........re-built them for a Mini......

..................who bought them from an MGA guy and then modified them as spares for his 1071 rally 'S'.

How much clearer do you or anyone else who reads this need it to be?
Did anyone else not understand? Of course they were no longer the right carbs for an MGA - they were MODIFIED TO SUIT A MINI COOPER 'S'

[Yoda]

I found that changing to twin HS4's made a huge difference to bottom end and mid range torque over an HIF44. This engine was running a 286 cam with big valve head and almost 11;1 comp. It took a while to get the right needles but once sorted, it pulled like a train right up to 6k, so i had grunt, speed etc but with a 4.1 diff, no fuel economy. I have now fitted a 3.4 diff but i reckon it would still give me good performance with a 2.9 diff.



In my opinion, a well set up pair of HS4 carbs is the way to go and Knowing Coopermans background, i am sure he will agree.

Oh, in case you wondered. the piccy is of Yoda undergoing a full makeover a few years ago. and the Carbs are Brand new old stock i had laying around for a while.

(EDIT)

To give you an idea of the spec i worked to, here is a clip from our club forum that i posted when doing the rebuild.

"ENGINE

1330cc A+metro block
polished and ported 12G940 head
Bladed/lightend/balanced crank
lightened\/ balanced con rods
competition pistons
duplex timing gear
286S fast road/rally cam
Decked block to match piston height
Brand new 1/12 SU, carbs
Free flow twin air filters
Competition fuel pump (electric)
RC40 manifold and exhaust.

RUNNING GEAR
yellow spot cone springs
Wood & Picket Adjusterides all round
SPAX shocks all round
Solid mounted front sub
Polybushed rear sub
adjustable camber kit on rear
adjustable camber, caster, kit on front
Poly bushed front suspension

BODY
1991 original Cooper sport MKV shell on original V5
Fully deseamed, except rear bumper mount (to be done later)
bulkhead boxed ready for the later Turbo installation."


The Turbo is now installed and this engine is now sitting in the yard waiting for the next project to commence

Edited by Yoda, 05 August 2012 - 06:47 AM.

[jamiestevenbell]

is it easy to narrow the throttle linkages on a set of hif4s from an mg what ever, im thinking could the inlet manifold from an mg be cut in the middle and narrowed and rewelded?

[JVA10L]

My view - stick with the HIF 44 - and Vizardise the throttle plate etc etc. It will be better than twin 1.5" SUs. Remember - each cylinder breathes independently - there is no worthwhile crossflow, in fact - the balance pipe disrupts flow - so a good single carb inlet manifold (with no water heating) will allow each cylinder to see a 44mm hole - instead of a 38mm hole in ONE of the twins. It will never see the hole in the other carb.

Why no water heating?

[bmcecosse]

Colder the better! Twin carb manifolds don't have water heating.

[freshairmini]

its better for performance. The reason being you will get more air or more specifically more oxygen into a air/fuel charge that is lower temperature because you can fit more molecules into that given space. air expands when hot so you will get less molecules in a give charge.

so cooler means more oxygen for better burn so more power. The reason they where fitted where for in the winter or something about better fuel atomisation. Either way its fine to have not connected to hot water.

Edited by freshairmini, 05 August 2012 - 02:14 PM.

[jamiestevenbell]

i dont drive it in winter any way but the conclusion of this all is... i cant use twin hif4s on a chopped mg manifold because of the angle?

[govig]

What needles did you end up with yoda?