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 Post subject: Twin SU Carbs - Hiff 44 1 3/4"
PostPosted: Thu Oct 12, 2017 6:06 am 
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Rotary?... What The?

Joined: Wed May 18, 2016 10:26 pm
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Location: S Devon - ENGLAND
Just fitted these rare Carbs to my NA S3. Back in the day it was said they give 150bhp.

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The Intakes Growl & Snarl when you floor it :D

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 Post subject: Re: Twin SU Carbs - Hiff 44 1 3/4"
PostPosted: Thu Oct 12, 2017 6:43 am 
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Spitting Seals
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Joined: Mon Nov 15, 2010 3:39 pm
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Location: Blackbum, Victoria.
How do you find they respond compared to a Weber or a standard carbie? I ran SUs on my Datsun years ago and wasn't especially impressed with them but I hope that your setup is better.

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green200b, aka Alistair

1981 RX-7 Sport, 12A - daily
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 Post subject: Re: Twin SU Carbs - Hiff 44 1 3/4"
PostPosted: Thu Oct 12, 2017 12:49 pm 
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Uber Post Whore
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Joined: Tue Jun 06, 2006 12:43 am
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Location: uranus
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hif7.. mid 90's// lots of pull from any speed any gear. but slow to react to fast throttle movements . have to play the oil mixture in the bath cup to get response

pretty typical of variable venturi carbs and mixers

i always thought mine where built so much better than anything from weber.

but

. black art

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when the going is hard, don't retard, remember your lubrication
27 years of rotary DIY
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 Post subject: Re: Twin SU Carbs - Hiff 44 1 3/4"
PostPosted: Thu Oct 12, 2017 1:02 pm 
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Location: uranus
twins are always a bastard to keep synchronised

there is expensive dial gauge indicators for piston lift to dial them together

but i found best trick is to make up a manometer on a board of ply . use cordial and clear tube and a few bent nails and an icecream container lid with a 10mm hole poked through ( and a 4mm one with the end of the clear tube poking through, next to it )

use the lid to seal against one of the carbs ( with the throttle stop ) and set a baseline mark on the manometer where it pulls the vacuum to
adjust linkage on the other carb using same test till they match

was using a mix of sewing machine oil and light machine oil in the cups . something you have to feel out for

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when the going is hard, don't retard, remember your lubrication
27 years of rotary DIY
tech forum is for tech questions.. private message box is for private messages
paypal : bumpstart13b@hotmail.com


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 Post subject: Re: Twin SU Carbs - Hiff 44 1 3/4"
PostPosted: Fri Oct 13, 2017 6:14 am 
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Rotary?... What The?

Joined: Wed May 18, 2016 10:26 pm
Posts: 33
Location: S Devon - ENGLAND
green200b wrote:
How do you find they respond compared to a Weber or a standard carbie? I ran SUs on my Datsun years ago and wasn't especially impressed with them but I hope that your setup is better.

They respond far better than the Stock Carb , but can not comment on the Webber.
There is far more Torque lower down the Revs & far much better when decelerating. The power is smooth right through the rev range & it feels like it is a lot quicker 0-80 mph.

Bumpstart - Thanks for the helpful advice, I have a bastardised set of MC Carb tuning guages (used them on Ro 80s) that helps to keep them Synced.

Still early days so the novelty factor is still there.

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Currently Own:- S3 RX7 FB & RX7 FC TII Vert
Previously Owned:- 2 x NSU Ro 80s.....2 x S2 FBs.....DKW W 2000....Suzuki RE5....Norton Commander


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