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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 - Throttle cable

I need a new throttle cable for the Frogeye (inner and outer). It has a 1275 engine with standard HS2 carbs. Moss list different part numbers for the Sprite mk1 and later models so is there a difference? I'm aware of the teflon coated inner advantage.
Bill Bretherton

Hi Bill

Use the later one as yours has the 1275 engine carbs and heat shield. The connections for the MK1 with the earlier carbs and linkage is slightly different
Bob Beaumont

ETA: whilst I was checking links Bob posted.

Bill,
my guess is that because of the different linkages on the Frogeye perhaps the inner cable is longer for the more antiquated linkage set up but most places seem to have one cable listed now for all, AHA5746.

(ETA: heater box(es) and blower/intake parts positions vary too)

Perhaps Moss provide a different cable or perhaps they list the same cable with two different part numbers and prices (using the same photos for both).

You have the 1275 heat shield, carb and linkages so go for AHA5746 or ask Moss exactly what the differences are between the two cables to justify the much higher price of the earlier cable, or buy from elsewhere.

http://www.leacyclassics.com/aha5746.html

https://www.ahead4healeys.co.uk/THROTTLE-CABLE-id12139.aspx
Nigel Atkins

Thanks Bob and Nigel. I might get an ebay one (no postage) then put a teflon bike cable inner in when it starts binding.
Bill Bretherton

Bill

You might want to go down the DIY route with a kit, or spares, from Venhill Cables?
https://www.venhill.co.uk/cables-and-components/universal-cable-kits/throttle-cable-kits.html
https://www.venhill.co.uk/cables-and-components.html

Cheers
Mike
M Wood

I'm with Mike on that. Definitely.
Before I got the Venhill kit I bought "correct" cables from both Moss and MGOC Spares. Both were disappointing. They fitted ok but both gave less than perfect throttle action.
The Venhill kit was not only better in every way but cheaper than the ready made cable.
Others advocate getting cable from the pushbike shop which for all I know maybe cheaper still.
Personally I'd stick with the Venhill kit because I know first hand how good it is. Just my 2c, other opinions are available.
Greybeard

Grey,
how did you get the Venhill kit cheaper than the cheap Moss style cable?
Nigel Atkins

Here's the link for the Venhill car throttle kits: https://www.venhill.co.uk/cables-and-components/car-cable-kits.html?p=1

Cheers
Mike
M Wood

I had a look, the cheapest Venhill is £40 plus whereas the Moss one is £7.50.The venhill would have to be cut to fit and the ends would need changing. I have to admit I have not had any problems with the MGOC one. Occasionally Alexander cable come up on -bay which are generally better quality.
Bob Beaumont

Hi Nigel.
I had a look and they do seem to have got a bit spendier.
However the kit I have used on 4 different cars now is this one:

https://www.venhill.co.uk/cables-and-components/universal-cable-kits/throttle-cable-kits/universal-throttle-kit-6mm-outer-235m-u01-4-102.html

Last time I bought it (for either a Mini or a Cortina - I disremember which) I recall it was £10.70 delivered which I thought was a bargain.

I did chuck out the adjuster from the kit as it's metric but there was no problem using the original adjusters. Same with the cable end yoke which is specific to SUs and not in the kit. I just cut the old cable to reclaim the bits I wanted to reuse.

ISTR that Venhill list it as a motorcycle kit though. Car specific kits are dearer.

Dunno if that helps.

Edit: you even get a choice of colours nowadays, which I never saw before. Modern bling eh...
Greybeard

Thanks Grey.

I think I must have just bought an outer cable with Teflon liner and a collection of bits 'n' bobs I thought I might need. IIRC I used the inner cable that came with a standard cable as I didn't trust my soldering. The Venhill outer cable is thicker (for the liner) and stiffer than the standard cable.

I wanted a longer run on the cable as the standard choice of routes aren't best but the cable rubbed on the underside of my (paint only) bonnet, so I shortened it, still rubbed so I shortened it again and it ended up the same length as previously.

But I did get red for bling!

Nigel Atkins

I might get one for the midget. The one that's on there at the moment is a right dog's dinner.

There's an adjuster at the bulkhead end, although it's not adjustable, it just sits there. The adjuster at the carb end is maxed out. The pedal end has a trunnion with a screw onto the frayed cable end, and there's quite a lot of slack.
Dave O'Neill 2

I'm sure those Venhill ones are good but do seem expensive.
Bill Bretherton

I'm inclining to the same view Bill. I'd be tempted by the bike shop option except that the nearest respectable bike shop to me is 90 miles!
After all you only need the Teflon cabley stuff - you already have the rest of the fittings.
Greybeard

I see Moss charge £14 for a standard 1500 cable, so it's not much more.
Dave O'Neill 2

Dave,
I think the 1500 throttle with its different carb end set up (that changed at some point?) would possibly benefit even more with a coated bike inner cable or cable liner or both.
Nigel Atkins

This thread has been perfectly timed and has provided plenty of food for thought as I've just arrived at the throttle cable fitting stage.

The old cable was frayed so needed replacing. The action has always been fine for me, so I decided against the Teflon option. I would probably have gone down the bike cable route, as the outer was fine but I didn't think going to buy a throttle cable for a classic would count as essential shopping so I went for a complete AHA5746 from MGOC.

It arrived yesterday and the outer is slightly longer than the original but the inner is longer by several inches. I'm not 100% happy with the ferrules as a) they're BZP instead of brass, and b) they are too big to sit properly in the socket at the pedal end, but the original was the same so no change there!

My Sprite is a 1967 Mk IV and had a very strange crank case breathing arrangement with no PCV when I bought it. To try to counter rear main oil seepage I installed a PCV along with Guy's(?) Illy Coffee Can catch tank arrangement. This cured the oil seepage problem but I was never happy with the way the PCV and its bracket obstructed the throttle cable.

I'm sure the Sprite must have had a PCV originally - the take-off was there but plugged with a bolt. Is there a correct set up for this combination or was the cable route always awkward? Would mounting the PCV remotely with a long pipe to the manifold work or does the connection need to be a short a possible to be effective?

The photo is a reference photo from before I started dismantling.

Colin
C Mee

I knew I'd forgotten something.


C Mee

Good tip I always use on cables - teflon coated or not - is to oil the insides. Hang the cable up, pull the inner out somewhat, wrap a paper cone around the outer end, fill it with oil, and let it permeate downwards between inner and outer.
Oggers

Colin
Someone with your PCV arrangement will hopefully comment - it does seem to obstruct the throttle cable. My 1275 is a later 12V which doesn't have a PCV but rather the breather pipe from the crankcase connects directly to the carbs. I think this change was in 1968.
Bill Bretherton

Thanks Bill.

My Sprite is a 1967 12CC. I would have gone for the later Y pipe system but, while the front carb has a vacuum take-off, the rear one doesn't.
C Mee

Colin,
as far as I remember all 1275 are vented to carbs, the 1098s had the metal chest covers and that diaphram arrangement.

Your breather hoses look oversized, they're usually 1/2" breather/vacuum hose.

Not sure what bracket you mean but the adapter that screws into the inlet manifold and joins the hose isn't that big, male outlet for 1/2" hose obviously.

I think things are close with the cable on the 1098s but not quite touching, bound to be lots of photos on t'web.

Check your dipstick is a good fit to the dipstick tube from the engine and you have a washer grommet where they meet as a seal.

If your rear carb doesn't have the port your front carb has then possibly they were born as twins.
Nigel Atkins

Nigel

1275s did have the PCV, possibly as late as '69 (mid '68, according to M*ss).

The bracket (69) attaches to a lug on the PCV valve and screws to the manifold.


Dave O'Neill 2

Dave,
how could you, shame me with something from Moss!

Looking in Terry Horler's book, I forgot, and the 12CC engines are down as have non-venting carbs.

I also forgot that (69) bracket but that would be out of the way of the cable surely(?).

Item 77 was the adapter I was thinking of which isn't that big, and 75 and 60 the 1/2" hoses, the ones on Colin's car look bigger/thicker walled (or perhaps it's just how I see the photo and they're the right size?).


Sorry Colin,
I thought I was having a lucid moment but I wasn't but you know not to trust my memory.

Still doesn't explain your carbs' port mismatch.

Page 104 of Terry Horler's book has (UK) carb assembly numbers, front AUC 9268, rear AUC 9269 and carb installation numbers AUD 136F (front) and AUD 136R (rear).

And ...
downloading and zooming in (to 400%) I can see your bracket and it looks more like strapping/ladder strip than item 69.

ETA: sorry done it again, in last post I meant - >>If your rear carb doesn't have the port {and} your front carb has then possibly they were{n't} born as twins.<< Why on earth did I think I might have been lucid.







Nigel Atkins

Colin, you clearly have a rogue front carb! It shouldn't have the air vent and certainly not on an engine using a pcv. Unless you can replace it then at the least make sure that breather vent is sealed.

The bracket referred to is to support the pcv against vibration, to prevent the stem part of the pcv fracturing.

That photo of your pcv looks taller than I think it should be. I wonder if it's off another car, a Morris Minor perhaps? Dave's Moss photo also makes it look shorter and with a short screw in neck. If the body of your pcv were lower then I think your throttle cable would clear it over the top rather than being kinked to one side.

And to add an answer to your actual question, then I think connecting the pcv to the manifold with a strong walled pipe would work. Not original of course, but the suction on the diaphragm would be the same. I suspect the pcv would need supporting vertically and not mounted sideways on.

Does your manifold have just the one tapping? I thought at least some have a second connection point just along the balance tube?
GuyW

If you were heading along the path of correcting your mis-matched carbs, my preference would be to look for a vented one for the rear and use them with hoses and Y piece for your crankcase breather system. As with the post '68 cars.

The problem with the pcv is that it connects to a high suction point on the manifold so relies on the diaphragm and spring arrangement to limit the amount of suction, which is otherwise too strong. It is also greatest on over-run, not on max revs when it is really needed. The later style gets its suction at the carbs which is much lower so no valving needed, and it then increases with revs, just as piston blow by does, so if set up correctly is more effective. There is also less to go wrong!
GuyW

Thinking about the crankcase breathing arrangement, does it affect fuel/air mixture? That sucked in air is adding to the air in the already mixed fuel/air, so must contribute to the overall mixture surely? In which case, security of hoses must matter I presume. Or have I got that all wrong?
Bill Bretherton

Bill

I would imagine Mr Bernoulli and his theory would automatically take care of any air upstream of the carb, but any ingress downstream of it may well give you a problem with the mix.
Oggers

Thanks for your thoughts and comments.

The more jobs I do on this car, the more of a mongrel I realise that it is!

Bracket first: This was supplied with the PCV by the Welsh MG Centre, so I assumed it was correct. It is clearly made for the job but obviously isn't the one that appears in all the Spridget catalogues. If anything I think it's taller than the official one but that would make the bend in the throttle cable worse.

Guy, there is another possible tapping just visible and painted black. It sits lower than the centre one and has defied previous attempts at removal. I think it might be a smaller diameter thread than the centre connector which is original.

Vacuum tapping: The tapping in the photo on the front carb has a plastic cap that looks to be purpose made and I've assumed it was original. Looking at the Moss diagram, I realise that it can't be for the crank case breathing as that is on the other side, I presume that's the take-off circled in the diagram. I guess it's for the distributor vacuum advance which mine doesn't have.

Is it my imagination, or are the plastic spacer blocks sometimes tapped for a take-off? If that would work then I could get rid of the PCV and go for a Y connector arrangement and solve the whole throttle cable problem.

As further evidence of my Sprite's mongrelness, while the carb bodies would appear to me a pair, if not the correct pair according to Nigel's source, being AUC 1341 (front) and AUC 1342 (rear), the float chamber tags, however, are not, with AUD 136 (front) and AUG 679 (rear). Some years ago I had to replace the rear adaptor (Item 36) as it had perished and the float chamber was at the wrong angle, so perhaps that problem is now explained.






C Mee

Colin,

From a quick check of Burlins site it appears that

AUD 136 is for a MG Midget Mk11 1098 or Mk111 1275 1967-1968.

Nothing found for AUG 679 but AUD 679 is for a 1974 998 Mini Clubman.
richard b

That looks more like throttle spindle than vacuum port.
Dave O'Neill 2

Thanks Richard, at least the AUD 136 is correct for a 1967 Sprite.

AUG was a typo, it's really AUD 679 and just confirms that my Sprite's a Bitsa!!

Dave, definitely a vacuum take-off. My Minor's vacuum advance pipe connects there and I should have realised (I'm just a bit slow sometimes and getting slower!).


C Mee

I see. The dissy vacuum port. It looks like the first photo has the rubber adapter on it, but the colour made it look a bit brassy.

Yes, the dissy vac does come off the front carb, so the rear one won't have a port. The crankcase vac ports are inboard and angled upwards. Also much larger diameter.
Dave O'Neill 2

Richard,
beware, as with all databases there are errors, or at least strange deviations, with the SU site information.


Guy,
looking at a photo of the set up on a 1098 engine in Terry Horler’s book the cable runs (close) to the side of the riser hose piece.
Nigel Atkins

Colin,
AUD 679 is a tag for a HS4 (1.5”) carb (according to SU site at least). - http://sucarb.co.uk/hs4-carburettor-for-a-austin-morris-mini-mk-ii-mini-clubman-4-cyl-1974-manual-automatic.html

There’s a suggestion AUC 1341/2 are for “SBU” (small bore units, sub-1275) possibly Austin Mini.

Only set I could find on (Canada) eBay, the seller has them for Spridgets’ OEM whether that is correct or not we know they can fit.

Photos below from listing. Note, the carbs are roughly put assembled as for sale as parts, and you might just be able to see AUC 1341 in the first photo, AUC 1342 is on the other carb but too blurred to see well.

https://www.ebay.co.uk/itm/324328295064

ETA: is that an open port in your manifold under your unusual bracket or is it just how it looks in the photo?






Nigel Atkins

Colin,
as it looks like your question has been missed -

>>Is it my imagination, or are the plastic spacer blocks sometimes tapped for a take-off? If that would work then I could get rid of the PCV and go for a Y connector arrangement and solve the whole throttle cable problem.<<

My answer is, in my very limited experience I've never noticed this and wonder if it'd be the best place in what are insulator blocks for heat shield to carbs.
Nigel Atkins

Plumbing into the spacers without a PCV valve wouldn’t work, as you would be the wrong side of the butterfly valves.
Dave O'Neill 2

Thanks Dave, I had just found a spacer with a take-off for a vacuum gauge online but hadn't ordered yet, so you've saved me some money.

Nigel, it's not an open port but a blind un-threaded hole.

Thanks for the info about the AUC 1341/2 info. I think mine is a relatively early 1275, so I wouldn't be surprised if some features of the 1098 installation were carried over (while stocks lasted?) but superseded as the 1275 run progressed. If I were to replace them I would go for the later versions to allow me to use the Y pipe set-up. Unfortunately I don't have a copy of Terry Horler's book - it's on my Wanted list and I have scoured the internet without success in the hunt of a picture of a correct version of my set-up.
C Mee

Colin,
I didn't expect it was an opening but given the other stuff, you never know, also given the state of the carb screw heads, I hope that wasn't you.

I thought I'd put the spacer would be the wrong side of the carb but I must have edited it out, Dave put it better anyway.

Later I'll see if I can find a photo I can post for you, I keep forgetting yours is an earlier 1275 Sprite, why not put up your 'Vehicle profile' for view with details.
Nigel Atkins

Colin,
best I can do is drawing in 'Image1' here. Although it's not to scale I'm sure your breather hoses are oversized. Plus unless they're a tight fit you also need them all jubilee-clipped, including the short riser hose between manifold and PCV.

See also instructions in 'Image2', also check the plastic vented and filtered oil filler cap is clear and clean (photo of that to follow) (and check for seal on dipstick to dipstick tube).






Nigel Atkins

Photo of vented and filtered plastic oil filler cap showing the filter (in modern ones at least) and how the bottom cover can be easily prissed off for cleaning.

Hopefully we can get this sorted so you don't need a coffee(!) tin as oil won't be going there.



Nigel Atkins

Thanks for the diagrams and servicing info Nigel. I'm fairly familiar with them but they're still useful for reference.

I'm sure the hoses are well over-sized for this particular task, though they are very thick walled 1/2" bore. The only hose I could find at the time that I could be confident wouldn't collapse under vacuum - although I doubt the pressure drop is very significant.

With the rebuilt engine having new pistons, rings and bearing seals etc. I would hope that the whole suction system might be unnecessary but I'll retain the Illy can for the time being (with a coat of paint to disguise it) so that I can get some idea of what's happening.

The state of the carb and float chamber screws is definitely not my handiwork but a new set has been added to my next shopping list.
C Mee

For the later Y type breather system the suction at the carbs at a steady 3000 rpm is surprisingly low. I measured with a vacuum guage some years ago and got a depression of something like just 2psi AFAIR. Unless that was the reading at tickover - I will have to check back.
GuyW

This thread was discussed between 04/02/2021 and 06/02/2021

MG Midget and Sprite Technical index

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