1 1/2 MGB Twin Carbs

[coopertim]

Would a set of MGB twin HS4 carbs be suitable for my 1293 engine? Possibly with a different manifold?

May be a silly question but help and advice greatly accepted before i part with the folding stuff!!

Cheers in advance
Tim

[atlanticdave]

Yup, I run these on my 1380 with no probs, just be down to needle choice at the end of the day.
https://www.facebook.com/photo.php?fbid ... =3&theater

[Cables]

yep should be fine, this is what I fitted to mine on a mini manifold. Just check the needles, on my spec they actually weren't a million miles out

[Smiffy]

All the linkage rods will need shortening, but nothing a hacksaw won't fix.

[CooperTune]

Just wondering out loud, what bowl bushings does a MGB use? I know with the 1 1/4s from sprite/midget and MG1100 I have to change those. Steve (CTR)

[coopertim]

Thanks for the replies guys!

Decision made then!

Cheers. Tim

[ianh1968]

Yup, I run these on my 1380 with no probs,
just be down to needle choice at the end of the day.

This might be of interest... It won't tell you what needles to put in based
on the diameter of your steering wheel and the colour of your furry dice,
but it will give you factual information on needles you select and want to
compare...

http://mk1-performance-conversions.co.u ... l_carb.htm

If the BHP of the MGB is about the same as your engine, the needles in
the carbs should be somewhere close.

[coopertim]

Cheers Ian

Thats fantastic info!

Have a great Christmas.

Tim

[App K]

Tim

Check out the float chamber part numbers first, as Im guessing they wont be the correct 30 degrees.

Should be AUC 3184, 3185, otherwise you may have to budget on spending another few hundred quid if you want them to perform correctly.

Brian.

[ianh1968]

otherwise you may have to budget on spending
another few hundred quid if you want them to perform correctly.

I have changed the angle of the float bowl simply by taking a hacksaw
to that loose insert piece which sits between the bowl and the carb itself...



Just twist the bowl round to the desired angle, then nip up the bolt.

Total cost : Nil

I've never had any fuelling problems as a result and no dyno operator
has ever even commented on the modification, probably because it
is totally invisible.

[App K]

otherwise you may have to budget on spending
another few hundred quid if you want them to perform correctly.

I have changed the angle of the float bowl simply by taking a hacksaw
to that loose insert piece which sits between the bowl and the carb itself...



Just twist the bowl round to the desired angle, then nip up the bolt.

Total cost : Nil

I've never had any fuelling problems as a result and no dyno operator
has ever even commented on the modification, probably because it
is totally invisible.

The correct H4 float chambers are all cast in one, complete with the "insert piece" Although I have tried heating and bending the arms in the past with limited success, as the insert piece carries the fuel to the float chamber and can distort quite easily.
Worth a try though.

[fred1380]

MGB carb are HS4 not H4

[ianh1968]

MGB carb are HS4 not H4

The carbs I am talking about are HS6...

When I wrote, I thought that they were all the same, within the
HS range.

To check if you have a loose insert:
1) Undo the Philips/Pozi screw that holds the choke activating arm to the jet.
This will give easier access to the bolt that holds on the chamber...

2) Undo the bolt, it's 1/4" Whitworth (I think)
which is just a bit larger than 7/16" AF.

3) The jet pipe will still be connected, so carefully pull the bowl off the carb
and look for the insert piece. It should become obvious if you have it...

Good Luck!

[Aussie Bill B]

Hi Coopertim,
For what it's worth - twin HS4s were fitted to Mk1 & 2 Ss in Australia by the BMC factory for NSW Police Highway Patrol pursuit vehicles
they supplied in 60s and 70s. I have one of these. It uses an AEG574 inlet manifold, a 997 Cooper cam (12A 122 ; a great road cam it is!) and
uses CP4 needles or #7for rich mix. It's a great package. Don't be afraid. It works with or without the 997 cam.
Bill.