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Austin seven special with Dual SU, straight floating?

Hi everyone from Italy!

As always with my Austin Seven special slowly rebuild, i have something to solve
and here i gently asking for a little support from the knowledge of this forum.

I have a Supaloy head with 4 branch exhaust and dual SU set up.

Unfortunately my mechanic told me we have a problem of exceeding fuel that split from the down part,
because the carbs installed had the floating chamber angled, when this should stay parallel to the ground.
I see some photos of Specials with dual SU and i thinkhe is right.

Now the question, where can i find the angled floating chamber that stays as it should?

attached photo of the current set up

Thank you as always for the invaluable help and i promise photos of the ended project!
Emanuel

IMG_7976
pic upload

Location: Italy

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Re: Austin seven special with Dual SU, straight floating?

Hi Emanuel,

You can get new float chambers at 20 Degrees and 30 Degrees here is a link to where you can buy them

http://sucarb.co.uk/float-chambers-spares/float-bowl-chambers/h-type-t1.html

Or something second hand but I am not sure which car had H type T1 angled SUs

Cheers, Mark

Location: Rokeby, Victoria, Australia

Re: Austin seven special with Dual SU, straight floating?

WOW thank you for this excellent helpful reply!

Cheers from Italy =)

Location: Italy

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Re: Austin seven special with Dual SU, straight floating?

Do you have enough room to adjust the angle on the inlet pipes so the carbs sit straight like the setup below?

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Re: Austin seven special with Dual SU, straight floating?

Ciao Emanuel,

You can get different angled float chambers but yours don't look far from vertical. I've got a similar pair on my Opal that work fine and they are about the same angle.

If they are both flooding have you got too much pressure from the fuel pump, 1 to 2psi is best? Alternatively are the needle valves in the top of the float chamber lid OK? Modern fuel attacks older materials and some float valves had rubber tips (Delrin?). Another way is to set the fuel level down slightly by 1 to 2mm and see if the flooding stops.

I hope you find a solution.

Dave

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Re: Austin seven special with Dual SU, straight floating?

Dave is right about the fuel pressure, of course. If you are using a Facet type pump the pressure will definitely be too high and the solution may be a fuel pressure reducing valve.

Regards,
Stuart

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Re: Austin seven special with Dual SU, straight floating?

Quote: stuart ulph
Dave is right about the fuel pressure, of course. If you are using a Facet type pump the pressure will definitely be too high and the solution may be a fuel pressure reducing valve.

Regards,
Stuart


I think it may depend on which Facet pump as they come in different pressures some are only 1-2 psi while others will put out 10 psi and the Chinese knock offs could be any pressure.

Cheers,

Mark

Location: Rokeby, Victoria, Australia

Re: Austin seven special with Dual SU, straight floating?

@Ruairidh Dunford - thank you very much, i have room but as i have an original period inlet manifold i would like to keep it original...

@Dave Armstrong - thank you Dave, i have the original depression fuel pump (not tested the car until now) so i assume
fuel pressure is right... do you think a facet or electric fuel pump will be needed in any case?

I have not done the complete test as i have a problem with my starter motor, but will do the checks of the carbs...

Thank you everyone for the support!

Location: Italy

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Re: Austin seven special with Dual SU, straight floating?

Quote: Ruairidh Dunford
Do you have enough room to adjust the angle on the inlet pipes so the carbs sit straight like the setup below?



The lengths people will go to in order to prevent the UJ hitting the handbrake!

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