15 replies to this topic

[Indigo]

Anyone fitted twin HIF40's to their mini?

Do they work OK at 30 degrees, like the old twin SU's, or should they be at 20 degrees?

[coopertaz]

forgetting angle for a mo what engine are you running to fuel it with twin 40mm carbs?

[Indigo]

forgetting angle for a mo what engine are you running to fuel it with twin 40mm carbs?

 

Engine is 1310, 10.6:1 compression, 276 cam, ported large valve head.  

Currently single 1&3/4, but the twin 1&1/2s look a heap better.

[GraemeC]

HIF4 not HIF40

 

Yes, have a set fitted and they work fine. Many people have done this conversion including Janspeed back in the day.

[Indigo]

HIF4 not HIF40

 

Yes, have a set fitted and they work fine. Many people have done this conversion including Janspeed back in the day.

 

Graeme, what type of manifold are they mounted on?  Something like the Minispares C-AEG489, or something different?

 

Not sure if they are HIF4, or HIF38 - how do you tell the difference?

[KTS]

measure the throttle bores; HIF4 will be 1.5" and HIF38 38mm

[mab01uk]

The Janspeed inlet manifold.

 

[bpirie1000]

Need to measure the carb inlet circle.

[Lplus]

I have fitted a pair of HIF4 MGB carbs to a mini HS4 type inlet.  The link rods needed to be cut down and the link rod socket nuts trimmed to give clearance with the closer port spacing.  The carb throttles open in the opposite direction to HS4 carbs so getting the linkage right is a bit of a pain.  Getting the lower nuts on is impossible with the carbs in place so slotting the lower holes and fitting nuts and washers very loose allows the carbs to be dropped in from the top and the nuts tightened.

The MGB has the timing vacuum takeoff in the manifold so I tried drilling and fitting a takeoff on one carb but  the throttle plate tended to cover it after opening and dropping the vacuum too quickly.  Fitting the takeoff to the bottom of the carb might work.

 

I believe the HIF38 has 4 bolt mounting instead of the 2 diagonal bolts of the HIF4 and I'm not sure if the HIF38 comes in handed sets.

 

They seem to work fine.

 

Edit - the fuel lines are a lot neater, but if the float needles leak you have to take the carbs off to sort it.

Edited by Lplus, 29 November 2023 - 02:32 PM.

[GraemeC]

I have used both Maniflow and cast MiniSpares C-AEG489 manifolds - both work well.

 

I build the carbs onto the manifold then fit the lot as an assembly.

 

As for throttle opening direction - there are different versions with them opening in different rotations.  I think the set I have is of an Allegro 1750 Sport and has its own throttle cable bracket to suit the throttle opening.

I think the vac take off is on the bottom as you describe

[timmy850]

From what I’ve seen:
HIF4 have HS style dashpots and two bolt manifold flange
HIF38 have HIF style dashpot and 4 bolt flange

[Indigo]

Thanks for all the info guys.

Based on timmy850 info and some double checks the ones we can get are MGB HIF4's.

So the throttle shafts probably open the wrong way, which is not ideal.

Thanks again for all the responses!

[bpirie1000]

Also need to measure the angle the main carb sit differently..

[Indigo]

Also need to measure the angle the main carb sit differently..

 

Yes, done that, sounds like it is not a problem when you read through the above.

[timmy850]

I found this today about the float angle

“ The HIF type is available for both single and multi carburetter applications, complete with all necessary connecting linkage, in throttle bore sizes of 38.1 mm (1.5 in) and 44-45 mm (1.75 in), and may be mounted at any angle from horizontal to 40° down draught inclusive.”

https://sucarb.co.uk...al-carburetters