18 replies to this topic

[minimejim]

I just wanted to know peoples opinions a series with twin carbs and if it's worth doing or is it too much hassle with the balancing and the reliability??

[Gr4h4m]

They are reliable if there rebuilt and not word out

[minimejim]

Worth the money? Much gains in bhp?

[HarrysMini]

Do a search.. This had been covered so many times.

Different people prefer different things, personally I think twin carbs are more interesting and depending on the engine spec, drive better too.

[timmy850]

Only if you are under-fuelled at the moment...

Smaller carbs are generally more responsive than a big single carb, assuming they are in good condition and are tuned together well.

[Dusky]

More low down throttle response, a bit more torque. You'll lose some top end BHP though.
IF you have the oney : go for it. They also add to the sound your mighty mini makes ;)Im using twin carbs and im loving it really.

[KernowCooper]

Why would you lose a little top end bhp ?

[joyce1bro]

I have just forked out some big $$ to go twin HS4's and bought some new K&N cone filters... I cant wait to get them on...

[leeuk]

I went from a single HIF44 to twin HS4`s on my 1380 and I could defiantly feel the gain in power after they were set up correctly,

I would recommend the change to anyone thinking of doing it, Quite a bit of an expense but I feel well worth the money when you lift the bonnet and they hit you in the face

 

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[Dusky]

Why would you lose a little top end bhp ?

Because (They told me) your engine is breathing efectively through 2 smaller carbs, wich would cost some at high rpm, becaue of the smaller carbs being restrictfull. Maybe AC can explain it a bit better

[finch661]

i loved my twin carbs (twin HS2), wouldnt say they give you anymore power, but the throttle response was great! plus having pancakc filters on, the sound was amazing!

Edited by finch661, 19 September 2014 - 07:58 AM.

[rally1380]

I just wanted to know peoples opinions a series with twin carbs and if it's worth doing or is it too much hassle with the balancing and the reliability??

 

Noone has asked you what engine spec you are planning on running (unless i missed something?) as that will dictate what carb or carbs you would be better using.

 

I used to have a HIF44 carb on my 1380 engined rally car and worked very well and is a very good carb.  I have changed to twin HS4's on a maniflow manifold due to wanting to use the car in historic rallies (HIF not allowed) and there is a difference in drivability and power delivery....and thats without getting the carbs setup on a rolling road yet.

 

Balancing twin carbs is easy and it is a total myth that they fall out of balance and are unreliable.....if they do that then something either wasn't done right in the first place or there is a problem with one of the carbs.

 

They do sound great but you do need to consider the considerable cost of twins over a single carb and what the car is actually used for.  As mentioned above, there are loads of threads regarding this question so have a google search and see what comes up.  Either way, best of luck.

[KernowCooper]

@Dusky the airflow will be how much air the cylinder head can flow, no matter how big or small the carb

[HarrysMini]

It depends on the size of twin carbs you are fitting. HS2s are on their limit with a lightly modified 1275 (c. 75hp), so you may lose a little top end power as they won't be able to flow as much as say a HIF44, at what 6-7k RPM. HS4s are more suited to modified 1275s and it will be less likely you will see a decrease in top end power.

 

In reality though, unless you're racing, losing a couple of horsepower at 6000RPM isn't going to be a great loss, the added low down torque and throttle response will more than make up for this.

[carbon]

Hillclimb midgets have been running twin HS2s with 1380s with power ouputs reckoned to be over 110bhp at the flywheel. Now this may be paddock talk but this particular car did post fastest time in its class (not mine I hasten to add...).

 

The main restriction with twin HS2s is not the carbs, it is the inlet manifold and the filter set-up. This hillclimb set-up used Maniflow inlet with good air flter and inlet trumpets. Cam was 286 scatter pattern.