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PostPosted: Sun Apr 08, 2018 1:01 pm 
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848cc
848cc

Joined: Thu Oct 03, 2013 5:19 pm
Posts: 8
Hi Mini Community,

I have a 1969 Mini K1100 that currently has extractors, maniflow twinbox exhaust (1.75") and twin SU carbs (1.25 inch) fitted.

It generally runs very well but unfortunately I have had a few problems with the carb setup
1. Seems to be running a bit rich.
2. Ongoing issues with fuel overflow/leakage from float system. I have fitted rebuild kit once already to both carbs that fixed for a while but has come back for some reason.
3. Fuel economy seems much lower than I would expect.

I am currently thinking of reverting to the simpler standard single carb setup. I have searched online etc. but have found conflicting advice & information. Most of the available info seems to be on boosting performance but my main priorities are reliability, low maintenance and economy without affecting everyday driving too much.

My questions are;
1. What would have been the standard carb & needle fitted to Mini K originally (not mentioned in workshop manual).. I suspect from forum messages here was a single 1.25" carb ?
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?
3. I was planning to stick with SU but there's a Weber 32/36 down-draft kit available for Moke & Mini, would that be worth considering for simplicity & other advantages they claim ?
https://www.lynxauto.com.au/mini-850-12 ... rsion.html
https://www.minimania.com/part/P4-004/C ... ir-Cleaner

Would appreciate any suggestions.

Thanks, Makes


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PostPosted: Sun Apr 08, 2018 3:01 pm 
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1275cc
1275cc
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Joined: Sun Apr 29, 2012 1:19 pm
Posts: 2939
Location: Wollongong, NSW
The K did have an HS2 (1 1/4") carb standard.

Another option is the single HS4 (1 1/2"). They were used on later 998 engines, mini-matics, Morris 1100S and other 1275 engines.

My 998 has an HS4 carb with a performance kit similar to what you have now. I used the supplied AAU needle and it works perfectly, and has good safe AFR and it pretty good on fuel (7-8L/100km)
http://www.minispares.com/product/Class ... STN17.aspx

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PostPosted: Sun Apr 08, 2018 8:27 pm 
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Joined: Wed Sep 08, 2004 9:27 pm
Posts: 15038
Location: Wodonga - Vic/NSW border
makes wrote:
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?


this ^^ HIF44

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PostPosted: Mon Apr 09, 2018 7:56 am 
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1360cc
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Joined: Sun Apr 11, 2004 11:32 am
Posts: 11154
Location: Sthrn HiLoLands, NSW, Australia
Makes, I don't know where in Oz you are...but why not consider getting the issues sorted out by tuning company?

If you are keen to spend some dollars on the machine then lift the head and get it flowed etc

I have heard that there were problems with the HIFs over the earlier HSs...so do some reading on the subject maybe...

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PostPosted: Wed Apr 11, 2018 9:27 pm 
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848cc
848cc

Joined: Thu Oct 03, 2013 5:19 pm
Posts: 8
Hi Guys, Many thanks for your suggestions, they are very helpful. I will research and consider these options further. Cheers, Makes


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PostPosted: Fri Apr 13, 2018 7:40 pm 
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998cc
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Joined: Fri Apr 01, 2011 8:33 pm
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HS4 (1 1/2") SU on a 2nd hand Metro manifold worked fine on my Daughter's slightly warmed 1100 (295 head, Peco extractor ......and a few other bibs and bobs..

If you can't find a Metro manifold then MiniSpares make a replica...

But there's no reason your twins shouldn't work properly... Mine haven't needed a tweek in almost 10 years.

There really is no alternative to a proper dyno setup done by someone who knows what they're doing... Trial and error is very expensive at $20 odd a needle. But you don't need an expert to set the needle valve properly ... what sort of fuel pump do you have?? SU's don't like much over a couple of psi..

Cheers, Ian


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PostPosted: Wed Apr 18, 2018 7:36 pm 
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1275cc
1275cc
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Joined: Sun Jan 21, 2007 9:16 pm
Posts: 3102
Location: North of the Harbour planning my next mini project
I have single 1 1/2” on two of my minis with 1100,s.
Extractors, modified head and 266 cam and setup on dyno is critical to achieving proper running and respectable power.
Dyno is not cheap but essential when trying to sort out any running issues.
And yes there are mini friendly or SU friendly dyno operators out there.

Where are you?

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1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged) :)
2015 HSV GenF GTS(occasional drive & tow car)
2013 MINI Countryman Cooper S


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PostPosted: Sat Apr 21, 2018 8:15 pm 
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1098cc
1098cc

Joined: Mon Nov 06, 2006 8:54 pm
Posts: 1512
Location: Hunter NSW
makes wrote:
Hi Mini Community,

I have a 1969 Mini K1100 that currently has extractors, maniflow twinbox exhaust (1.75") and twin SU carbs (1.25 inch) fitted.

It generally runs very well but unfortunately I have had a few problems with the carb setup
1. Seems to be running a bit rich.
2. Ongoing issues with fuel overflow/leakage from float system. I have fitted rebuild kit once already to both carbs that fixed for a while but has come back for some reason.
3. Fuel economy seems much lower than I would expect.

I am currently thinking of reverting to the simpler standard single carb setup. I have searched online etc. but have found conflicting advice & information. Most of the available info seems to be on boosting performance but my main priorities are reliability, low maintenance and economy without affecting everyday driving too much.

My questions are;
1. What would have been the standard carb & needle fitted to Mini K originally (not mentioned in workshop manual).. I suspect from forum messages here was a single 1.25" carb ?
2. I have heard that later HIF carbs are an improvement (mainly because fuel float is at bottom of main carb body) ?. Would a HIF38 or HIF44 from UK with an appropriate needle work perhaps ?
3. I was planning to stick with SU but there's a Weber 32/36 down-draft kit available for Moke & Mini, would that be worth considering for simplicity & other advantages they claim ?
https://www.lynxauto.com.au/mini-850-12 ... rsion.html
https://www.minimania.com/part/P4-004/C ... ir-Cleaner

Would appreciate any suggestions.

Thanks, Makes

Any su can haveoverflow issues check float heights I would look at what a 1100 sprite would have as a needle and spring set up would be close I would assume


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PostPosted: Mon Apr 23, 2018 3:06 am 
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848cc
848cc

Joined: Fri Jan 02, 2015 3:59 am
Posts: 41
I had problems with my twin SUs flooding couple of years back, I fitted an in-line fuel filter just before the carbs and have not had any problems since. I think it was specs of rust from the tank stopping the needle valve from sealing, and that was using viton tipped type.


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PostPosted: Sat May 05, 2018 12:37 pm 
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848cc
848cc

Joined: Thu Oct 03, 2013 5:19 pm
Posts: 8
Hi Guys, thanks for your ideas and suggestions. I will try fitting a fuel filter immediately before the carbs. A proper dyno tune & carb setup sounds like the best long-term solution to find best fuel mixture. I am located on the Gold Coast QLD. Thanks.


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