34 replies to this topic

[adam_93rio]

just wanting to know if an inlet manifold for twin 1 1/2 su's will be ok with 1 1/4 twins carbs on

[adam_93rio]

just realised how confusing that sounded,

will inch and quarter carbs work well with an inlet manifold for inch and half carbs?

[bmcecosse]

Yes - except the standard BMC twin SU manifold is hopeless anyway - so it will still be hopeless with twin 1.25" carbs! You really would do better with a single 38 or 44 - on a GOOD manifold.

[adam_93rio]

im asking for my dad who has a mk1 with a 998, he already has the twins as its more of a period thing to have twins

hes found a twin inlet manifold for sale, but it is slightly bigger, i cant see this restricting flow or anything as its bigger.

it should all physically fit together tho shouldnt it

[bmcecosse]

Yes - it will fit together. You could consider blocking off the cross tube with cataloy - and then smoothing it out to make two nice straight inlets! The ideal inlet for twin SUs is like a Weber inlet -two long straight tubes! It's the daft crosstube that messes up the air flow.

[adam_93rio]

this is what the title is on it so will it be any good?

B SERIES TWIN 1 1/2 INCH SU CARB INLET MANIFOLD. bmc.

[adam_93rio]

Yes - it will fit together. You could consider blocking off the cross tube with cataloy - and then smoothing it out to make two nice straight inlets! The ideal inlet for twin SUs is like a Weber inlet -two long straight tubes! It's the daft crosstube that messes up the air flow.

right cool, i always wondered about that when i saw pictures, bit of foam filler should sort it (just kidding)

ill let him know in the morning when he gets home from work

thanks for your help

[bmcecosse]

Ah well - that's for a B series engine - ie MGB!! I used one of these many moons ago - just cut the crosstube to shorten it - and joined it with rubber tube and two jub clips. It worked well enough until we made a 'weber' like manifold. So - NO It won't directly fit your A series engine. Best get the right thing - I suggest Maniflo may be worth checking out!

[camp freddy]

haven't the 11/4 and 1 1/2 carbs got a different manifold bolt pattern ??

[bmcecosse]

Not if both are HS type.

[camp freddy]

Not if both are HS type.

isnt the hs2 vertical holes and the hs4 diagonal ?

hs2 manifold

http://www.minispare...ty=pb&pid=33131

hs4 manifold

http://www.minispare.....20INLET HS4/6

Edited by camp freddy, 15 January 2010 - 02:35 PM.

[Asphalt]

Not if both are HS type.

That's just plain wrong.............

@campFreddy:
You'r dead right!

HS2 (1 1/4") = vertical stud pattern
HS4 ( 1 1/2") = angular stud pattern

The H4 (1 1/2") has a vertical stud pattern.

However, a minifold like in the second link can be drilled to take HS2s

Oh and once again... Twin SUs need a balance pipe to stay in sync...

Edited by Asphalt, 15 January 2010 - 02:49 PM.

[adam_93rio]

ill let him know to get one from minispares or something like that. at least then if it turns out to be wrong we can send it back

[Asphalt]

That's the safest way, yes. There are also a lot of non-mini twin carb manifolds for the A-series engine which don't fit a Mini. A Mini needs them to sit at 30°, Sprite etc. manifolds only give 20°, and the jets foul a Mini's bulkhead

[adam_93rio]

That's the safest way, yes. There are also a lot of non-mini twin carb manifolds for the A-series engine which don't fit a Mini. A Mini needs them to sit at 30°, Sprite etc. manifolds only give 20°, and the jets foul a Mini's bulkhead

right oh, thanks a lot, i found one for a sprite and he said on it will fit mini, when i questioned him it turned out they wouldnt because of the bulkhead issue
being for a mk1 its not something my dad wants to do