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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Single carb for 1098

Can anyone recommend the best single carb and manifold setup to replace the standard twin setup on a 1098 sprite. Thanks.
Andy Potter

Having done some research in the archives I think I may have answered my own question (should have looked first :)). General concensus is the HIF38. Has anyone used the manifold below from minispares? Does this give clearance under the bonnet.

If anyone has suitable parts for sale, let me know. Thanks.


https://www.minispares.com/product/Classic/Exhaust_and_manifold/Inlet/Inlet/C-AHT770.aspx?110202&ReturnUrl=/shop/classic/Exhaust~and~manifold/Inlet/Inlet.aspxBack%20to%20shop
Andy Potter

Andy - someone who knows will be along shortly.
I don't think that Minispares manifold will fit under the bonnet. The Titan is the classic manifold for a HIF, though I don't know whether it's available, but there's another very flat manifold that people have used, whose name escapes me.
I will seek it out.
Nick and Cherry Scoop

There's one on ebay now. Sadly, it's £180. but it leads you to other solutions. Someone will know.
Nick and Cherry Scoop

Why bother - problem with your twin 1.25 inch SUs? Why not rebuild them instead of going for a single 38 carb (or single 1.5 inch SU) which were standard fit on many ordinary BL 1098cc or 998cc cars. The twin 11/4 SUs should be up to the job of feeding a 1098cc engine, or capable of being so, depending on tune and spec of engine and condition of carbs.

Cheers
Mike
M Wood

I am with Mike to be honest. Twin 1 1/4" are good to 118 at the engine MGOC racing ( tweaked spindles).
If you are carbless and manifoldless then the 38/1.5 SU is sweet.
We have set up two 1275s with fast road head and 266 Kent cam on single 1 1/2 sus they are really good and still pull good top end power, around 85 at flywheel (70+ at wheels).

Peter
Peter Burgess Tuning

i use a Maniflow item on both my mini and midget, the Titan one is always a pricey thing if you can find one.
I should point out that i am using the HIF44 though.
P Bentley

Peter

Hopefully you’ll be setting up an MGB with a single HIF6 soon... once I get time to fix the fuel pump.
Dave O'Neill 2

Vroooooom!
Peter
Peter Burgess Tuning

Thanks for the comments guys.
My thoughts were that the single carb would be little easier to set up. I have fitted new spindles etc to the twins I have but seem to periodically tweak them. One thing I haven't changed are the needles, mainly because I don't know what to pick. The engine is in good condition but standard bore, cam etc and maniflow exhaust manifold. Any suggestions on needle size if I stay with the twins?
Andy Potter

Spotted this manifold, the 10 degree angle makes me think it could be ok for bonnet clearance. Has anyone tried one?

Look at this on eBay http://www.ebay.co.uk/itm/263591467877
Andy Potter

That looks interesting, Andy.

I'm wondering why a Mini would use a 10º manifold, though.
Dave O'Neill 2

Dave yes I am thinking the 10 degrees is faces to face on the flanges? Any idea what a normal mini sport one is. I have asked the seller but still waiting for a reply, I mog ht just take a punt as it's much cheaper and easier to find than the Titan ones.
Andy Potter

Andy,
I've got a feeling Peter might ask, what air filters do you have? :)
Nigel Atkins

At the moment K&N pancake filters on the twin carbs.
Andy Potter

Stub stacks?

What needles are fitted now?

Any other deviations from standard other than K&N air filters and Maniflow manifold?

I don't know the answers just setting up for hopefully Peter to swoop back in.

Once the twins are in good condition and the engine and timing set up fully the twins should need very little future tweaking.
Nigel Atkins

Good idea, Andy. At that price I was thinking I might get the other one, just in case.
Nick and Cherry Scoop

Yes stub stacks, new spindles, unsure of needles but they were next on list to replace. Every thing else is standard.
Andy Potter

You'll need to know the needle numbers you have now (and that they are the same, not an odd set) to know their profile to change to a different profile.

Of course this doesn't allow for wear or alteration of the needles - or wear, misalignment, mismatch, incorrect part(s) or assembly of other parts that could influence running and tuning.

Looking at your Vehicle profile you have electronic ignition, which type/one?

I'm just thinking there may be a relatively simple and inexpensive solution to your current issue that saves you spending money on a new carb and manifold, perhaps that could be explored first.
Nigel Atkins

Nigel, I changed back to Lucas distributor and points a couple of years ago as the cheap electronic module gave up the ghost. These are all good.
Andy Potter

Andy

Worth checking what the standard carb needle for your car, model and year should be and then what is fitted. You can find this info on SU Carb website (Burlen Fuel Systems) under 'vehicle application' as well as in the works parts manual, Terry Horler's book etc (Nigel will be along shortly tell you if it is in the Driver's Handbook and suggest you buy one).

As others have said the current needles could be worn.

When I rebuilt my poorly running carbs I found two different needles! Hopefully my previous owner did not work on your car.

I would expect to replace the needles as part of a full carb rebuild. You can buy them direct from SU Carb Company (Burlen) or the usual MG parts companies.

Have you replaced all the rubber fuel hose including the piece that links the carbs, and checked the tightness of the connections? Also did you check and clean the fuel float bowls for rust and dirt from the tank, check the float needles were OK and then put in new gaskets for the lids?

Best wishes
Mike
M Wood

Check for air leaks at the manifold gaskets. Perfect carbs won't adjust correctly if there is even a slight air leak downstream.
GuyW

Thanks fellas, looks like I need to find time to do a proper investigation. I must admit I haven't used the car as as much as I'd like over the last couple of years which probably doesn't help. Last year I only managed 250 miles! Many of the parts mentioned have been replaced but over several years, the air leak is probably a good shout as I had the engine out to do the clutch 2 years ago and replaced the exhaust manifold at the same time.
So in conclusion not much (if any) advantage with a single carb as long as I set the thing up properly :)
Andy Potter

Andy, initially I thought you just fancied a single carburettor for ease of setting-up, and you mentioned having to tweak them from time to time, which I guess means getting them balanced and idling correctly, but are you actually unhappy about something in the car's performance?
Nick and Cherry Scoop

Andy,
you won't like this further questioning but same as with the electronic ignition I can't know and only ask, have you checked the carbs - match each other, match to the model of car, (a favourite of mine is matching dashpot chamber to it's piston), and of course to check the needles.

You may have already checked but as Mike and many other of us have found previous owners do strange things to our cars.

Some John Twist videos with useful info -
44 Secrets of the SU Carburettor Part 1 of 2 - http://www.youtube.com/watch?v=7GRAcqDySog

43 Secrets of the SU Part 2 of 2 - http://www.youtube.com/watch?v=60Bj_2cZQnc

41 Matching SU Air Pistons - http://www.youtube.com/watch?v=IfU47Oqq9wA

232 MG Carburetter Needles and Seats (odd sizes) - http://www.youtube.com/watch?v=pVX_JClyeDQ

147 MG Carburetter Tuning - http://www.youtube.com/watch?v=4nvGLgO6pj0
Nigel Atkins

Nick
Yes spot on that was the original question. 😁 I do seem to have gone off at a tangent, sorry.
Nigel
The setup does all match and I've always been careful to keep the parts in 'sets', it's not really that I can't get it to run well it just seems to need tweaking from time to time and thought the single carb would be easier. If I got a bit more performance that would be a bonus.
Andy Potter

Andy,
fair enough, you do also need to check the sets were previous matched correctly before keeping them the same.

All things being equal, without wear, you shouldn't need to tweak so something is amiss. If it's between or by the carbs then changing them should change that situation, just seem a shame.
Nigel Atkins

Thanks for all your advice.
Andy Potter

This thread was discussed between 26/08/2018 and 02/09/2018

MG Midget and Sprite Technical index

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