May seem crazy but has anybody considered fitting SU carbs to a modern (Zetec 2.0) engine?

I've used an ex Mini 1 1/4" SU on a vintage car and it worked really well without modification to jet or needle, presumably because it effectively adjusts itself in response to the vacuum in the induction system.

SU's are available very cheaply at autojumbles and boot-fairs and fitting say 4 off 1 1/2" units would not appear to be inpossible.

I know it would be easier to go for Bike Carbs or save up for twin DCOE's but I fancy trying something new unless there a good reason why it won't work.

Any feedback would be welcome.

SU carbs are used quite a lot in autograss racing on various more modern engines, though I have never seen them on a Zetec etc.

Plenty used on the vauxhall 8 valve engines in class 2 cars where only one barrel of induction is allowed.

You might be pushing your luck on flow rates on a zetec though, you will probably find that you need to make a twin carb manifold that allows all 4 cyls to draw from both carbs, which will not be easy to do!

If 1 carb per 2 cls is ok then one like this would do:





[Edited on 23/11/05 by NS Dev]

have a look at Jacko's archive

example: http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=Imgp1504.jpg

Cheers

Mark

A single SU is fine almost perfect simple form of carburation --- but a pair are a pain in the neck, while triple as on the E Type were b****** to set up.

One SU per cylinder dosen't work well , the heavy piston gets pulsed up and down like crazy which is why it was never used in the 50s and 60s.

So you would need to use a pair with a balance tube.

With the old Lotus 1558cc wincam engine the Twin Stromberg head was about 15 -20 hp down on the the Weber DCOE /Dellotro engine with the same SSE cams.

[Edited on 23/11/05 by britishtrident]

John P - As Mookaloid said I made my own manifold to take two 1" 3/4 su's from metro 1300cc. Ive used them for 2 summers now with great success. As you say they are quiet cheap to pick up at scrap yards etc. I am now in the process of making a manifold to take ZX9R carbs to see if I can get more bhp out of the engine The only problem I found with the su's was a flat spot at 4000 revs which ive tried to rectify maybe a rolling road would have sorted this. All the best Jacko

I've got a pair of old rover V8 SUs if anyone wants 'em.
These are the really old ones where the choke works by heaving the entire float chambers up & down. I can't remember the diam but someone on here will know.
Bob C
PS - SU stands for "skinner union" - nothing technical whatsoever!

quote:

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Originally posted by Bob C
I've got a pair of old rover V8 SUs if anyone wants 'em.
These are the really old ones where the choke works by heaving the entire float chambers up & down. I can't remember the diam but someone on here will know.
Bob C
PS - SU stands for "skinner union" - nothing technical whatsoever!

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The problem that I was getting at when talking about trying to feed all 4 cyls from both of a pair of carbs is that the carbs will be a bit limited in terms of airflow.

On a fairly docile 2ltr pinto that should be no problem, but could be on a 170hp zetec!

You have to remember that a single carb or twin carb setup is exactly the same as far as the engine is concerned in terms of airflow "per cylinder" i.e. each cylinder still only draws through the one carb.

The rover v8 setup is different as it draws all cyls from both carbs.

Jacko,

Do you know what sort of power your getting from your twin SU set up?

John.