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Post by james on Oct 29, 2019 4:03:11 GMT
Hi Guys, Am I able to use any type of dual SU carbie setup for the Austin 1800? I have seen a few for sale but they have different numbers such as HS5 and HS6..... The ones I have my eye on are listed as HS6 1 3/4..... they are "Well used" but I reckon I could clean them up so they look quite good.... The engine they would be going on is a new rebuild, +.40 pistons and a very mild cam. Thanks  |
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Post by Penguin45 on Oct 29, 2019 15:53:40 GMT
Can be done.
FOR.
Perky acceleration.
Economy on long runs.
Against.
Appalling fuel economy around town.
Custom exhaust manifold, or attack your present one with an angle grinder. Getting to be rare things.....
Improvise linkages.
Improvise air cleaners.
Spend days of your life balancing the little s@ds and trying to work out the correct needles.
MGB inlet manifold drops straight on.
I suppose the thing to bear in mind is that the MGB and "S" engines were developed as whole things - simply dropping on the extra carb won't take you there. I ran SU HIF44s on my 18/85 for some years. Fun, but never quite right.
Chris.
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Post by dave1800 on Oct 30, 2019 8:07:50 GMT
The 1800S used the MGB camshaft profile with 1.75" HS6 carbs. Difficult to find the manifold. As Chris noted the MGB inlet manifold bolts straight on and uses 1.5" HS4 (later HIF4) carbs. With the 1800S or standard MGB camshaft the MGB carb needles are a good starting point but may need to be a bit richer as the MGB is a lighter vehicle. Do you know which cam is fitted to the engine, that is key to being able to set the correct mixture, valve and ignition timing and get the best from the engine - safely. David Hi Guys, Am I able to use any type of dual SU carbie setup for the Austin 1800? I have seen a few for sale but they have different numbers such as HS5 and HS6..... The ones I have my eye on are listed as HS6 1 3/4..... they are "Well used" but I reckon I could clean them up so they look quite good.... The engine they would be going on is a new rebuild, +.40 pistons and a very mild cam. Thanks |
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Post by andrewa on Oct 30, 2019 12:33:42 GMT
For what it's worth, I wouldn't bother - I've got twin carbs on mine (it's an S) but am not convinced - particularly in a relatively mild state of tune like mine is - that it adds much - if anything!
Reminds me a bit of the Rover 2000 and 2000TC in the '60's/'70's - more of a marketing gimmick in some respects.
Your bigger gains are going to come from flowing the head more than anything IMHO if that's what you're after.
Plus as Chris says it's double the aggro getting them right and keeping them right.
Cheers
Andrew
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Post by dave1800 on Oct 30, 2019 12:52:05 GMT
Is that really you Andrew!! Actually I agree unless you are into lots of high speed driving which is almost impossible in the UK now, the single carb is so easy to set up and doesn't need constant balancing. Downton mods on the head to make it flow better initially used the single carb and the result was a very flexible and pleasant engine. I recall that the twin carb versions really only came into their own over around 4000rpm.
David
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Post by andrewa on Oct 30, 2019 17:41:50 GMT
Yes 'tis I - not a hacker!
But have to disagree with rubbish MPG around town - mine's always between 27 and 32 which isn't too bad IMHO.
Back to the question - I'd give it a miss!
Cheers
A
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Post by snoopy11 on Oct 30, 2019 19:54:35 GMT
You could always go dual fuel injectors 😁😁
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Post by james on Nov 1, 2019 1:44:00 GMT
Hi Guys, I greatly appreciate your replies..... the dual carbies will be used for a future rally car... my wife said I can do one about a week ago so woopeee!!!! If is going to be a long process but if I can post pics of me at a race in say 3 years then that would be awesome I was lucky to grab these ones recently, it was a guess but I think they are good ones... I think they came from a wolseley?? ![]() Attachments:
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