Twin SU's
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- Minor Legend
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Twin SU's
I am building for my sidevalve an inlet manifold to use 2 rebuilt HS1 carbs. Each carb has its own connection to the block to supply two cylinders and I am about to join the two together to make it 'one manifold assembly'
However all the manifolds I have seen (including the one my carbs came from - Austin Healey) have the two inlet ducts joined together?
Any ideas why this is?
However all the manifolds I have seen (including the one my carbs came from - Austin Healey) have the two inlet ducts joined together?
Any ideas why this is?
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- Series MM Registrar
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Its a balance pipe but don't ask me anything technical. I have a twin carb inlet manifold and enough H1 carbs to make up a pair. All I need is the linkage. Also a decent 4 branch exhaust manifold would be useful as twin carbs with the standard manifold would be a waste of time. What needles do you intend using?
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- Minor Legend
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Balance pipe! thats what it is, but Webers don't seem to use them - strange. I think I will just join the two short manifolds together with the possibility of balancing later. I am going to use the standard exhaust manifold for now (its a new stainless system!) and see how it goes and perhaps look at the exhaust at a later date. Is a 4 branch manifold sold for the sidevalve? or is this something I will have to make/have made?
I was going to use GG needles to start with as it is these that are used in the Healey Sprite setup whee they allow the engine to develop about 35BHP
I have the linkage but will need to replace a couple of bits.
Not sure weather I should try and use the original silencer or go for something different, ram pipes?
I was going to use GG needles to start with as it is these that are used in the Healey Sprite setup whee they allow the engine to develop about 35BHP
I have the linkage but will need to replace a couple of bits.
Not sure weather I should try and use the original silencer or go for something different, ram pipes?
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- Minor Legend
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Like this? Not much power improvement due to the extra carb, but, it helps power by removing the hot-spot heating of the inlet charge and straightens the otherwise tortuous path that the air has to flow through to get to the cyliders. This is why it is a good method of improving performance. The balance pipe helps smooth out the pulses of inlet air since the firing order means that one carb sees 2 pulses and then 2 pauses without the balance pipe (IIRC).
Exhaust manifold? I got some backplates laser cut and bought a 4-cyl motorbike manifold from a scrapyard but wasn't happy with the result. there was some talk of manifolds from Aus but nothing so far.
Exhaust manifold? I got some backplates laser cut and bought a 4-cyl motorbike manifold from a scrapyard but wasn't happy with the result. there was some talk of manifolds from Aus but nothing so far.
Cardiff, UK
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- Minor Legend
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- Series MM Registrar
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If there is a demand for it I will chase up that Australian exhaust system. It's likely to be expensive with the shipping costs.
I will find out what needle setup is used in the Alta twin carb head.
I will find out what needle setup is used in the Alta twin carb head.
Last edited by mike.perry on Thu Aug 28, 2008 1:23 am, edited 1 time in total.
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- Minor Legend
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- Minor Legend
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- Minor Fan
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I know of two also....they aren't for sale either!...
The Derrington 4 branch can replace the front section to the silencer, although they did make a complete system.
I have a 4 branch made for my Alta Shorrock set up, I just need to collect it from my friend who made it, I'll post a picture when I finally do collect it...it may help.
I have a picture of my Derrington manifold somewhere and one of a Derrington on a car with twin carbs, I'll look it out...
The Derrington 4 branch can replace the front section to the silencer, although they did make a complete system.
I have a 4 branch made for my Alta Shorrock set up, I just need to collect it from my friend who made it, I'll post a picture when I finally do collect it...it may help.
I have a picture of my Derrington manifold somewhere and one of a Derrington on a car with twin carbs, I'll look it out...
Supercharger Engineering
MMOC No 121
52 Series MM convertible, Alta head, supercharger and 1955 Series II facelift van
MMOC No 121
52 Series MM convertible, Alta head, supercharger and 1955 Series II facelift van
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- Minor Legend
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I'm guessing these carbs are ex Mk1 Sprite - in which case they need to be mounted horizontally. Can you get that inlet manifold in past the original ex manifold ? Balance pipes like that will be ok if joined up with stout tubing - but they really won't do much, if anything! I would (and did) just run with straight pipes and no balance.
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- Minor Fan
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Rob, I wish I could get him to make some more, it took me ages to convince him to make a set for my Alta Shorrock combination.
The set he made is no good for the standard or Alta engined cars as the pipes are bent around to miss the Shorrock compressor....plus they dont have the twin SU manifold fabricated.
I will post the pictures of my standard Derrington manifold and provide dimensions if anyone is thinking of getting some made.
regards Keith
The set he made is no good for the standard or Alta engined cars as the pipes are bent around to miss the Shorrock compressor....plus they dont have the twin SU manifold fabricated.
I will post the pictures of my standard Derrington manifold and provide dimensions if anyone is thinking of getting some made.
regards Keith
Supercharger Engineering
MMOC No 121
52 Series MM convertible, Alta head, supercharger and 1955 Series II facelift van
MMOC No 121
52 Series MM convertible, Alta head, supercharger and 1955 Series II facelift van
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- Minor Legend
- Posts: 1438
- Joined: Tue Jan 30, 2007 10:09 pm
- Location: Essex
- MMOC Member: No
I am still progessing with the twin carb mod, even though other projects keep coming along -new shed, greenhouse dismantle etc!Some pics of where I am at:-
http://i248.photobucket.com/albums/gg17 ... ifolds.jpg
http://i248.photobucket.com/albums/gg17 ... fitted.jpg
http://i248.photobucket.com/albums/gg17 ... fitted.jpg
I am at present trying to combine he carb inlets so that they can draw air through the orignal silencer
http://i248.photobucket.com/albums/gg17 ... ifolds.jpg
http://i248.photobucket.com/albums/gg17 ... fitted.jpg
http://i248.photobucket.com/albums/gg17 ... fitted.jpg
I am at present trying to combine he carb inlets so that they can draw air through the orignal silencer
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- Series MM Registrar
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