MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

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 - Stub Stacks in Original Filters

Has anyone fitted stub stacks inside the original air filter housings? I’m trying to get the best I can from my twin 1 1/4s but keep it looking standard. I’ve got a pair of K&N elements ready to fit but want to try and get some full radius stub stacks in there as well as I think they make a big difference.
I can’t see how I will be able to get them to work with the long bolts and spacers inside the housings. These are the type I’m looking at fitting:

http://www.med-engineering.co.uk/ancillaries/stub-stacks/med-stub-stacks

It goes very well as it is to be honest but I want to optimise what I’ve got before it goes to PB to be set up.

Thanks!

John Payne

Have you asked Mr Burgess about stub stacks? Surely he is the man you should be consulting.
Mike Howlett

https://www.med-engineering.co.uk/med-stub-stacks

They've been tested on their 110 Superflow flow bench but would that give the same results as inside some saucepan filter housings, £10-£15 for a set of rough cast that might be as good or near enough not to be noticeable or even perhaps better being rough, why not ask PB. (ETA: Mike posed whilst I was typing.)

For the fixing the engineers might have better ideas, I suppose some accurate sleeving over the bolts to push/clamp tight the stub tacks and their gaskets. Or threaded (UNF) bar as long studs with or without sleeving and nuts and washers, threadlock at carb end and nuts instead of bolt heads holding the filter housings at pan end, they need to be secure but not murder tight.

Nigel Atkins

Well I think the general consensus is that there are good benefits from having some form of radius stub stack/ram pipe at the inlet of the carb so I’m not really asking whether I should have them, rather will they fit or has anyone fitted them.

Whether they will make any difference inside a restrictive standard filter housing is another question though!

I have one inside the K&N of the HIF44 on my Sprite and that made a noticeable difference.

It probably will have to be something like you describe Nigel, I definitely can’t see those horrible crimped up spacers being much use.

Basically I’m just trying to get it ready before booking it in. It has one of PB’s Econotune heads on it so I’ll be interested to see how it does, seems nice and torquey.

John Payne

As usual I made my own. A ring of metallic resin filed and sanded to shape. It's also worth modifying the carbs for better flow - lots of guidance in Vizard's book.

Les


L B Rose

MED sell the foam filters so I'd be asking PB before buying the stub stack to the open filters.

I've no idea why I put UNF I meant UNC, perhaps you could get a UNC bolt with more thread on it doing away with the need for sleeving, looking at the ones supplied BH505361 - 5/16" UN - C x 4.5" the thread part is only at the end. Or perhaps a longer bolt or (setscrew?) cut down to length.
Nigel Atkins

I have one question, is the spacing between the carbs the same on a Spridget as it is on the Mini since it looks like they specialize in Minis. Since I've never work on a Mini, I have no idea. I know that the head side is the same but what about at the front of the carbs?
Martin

Does vizard, or anyone for that matter, give the air flow figure for the standard spridget saucepan casing? It maybe that it is so restrictive, as to negate any improvement that might otherwise be gained by stub stacks.

Given K&n's are intended to be sandwiched between two plates, and not encased, I can't see how you could optimise the benefit of either the filters or the stub stacks, if they are inside saucepan casings.

But given how SS's work to improve air flow into the carb mouth, especially with free flow filters like k&n's, it can't help but improve it, even inside a saucepan, --- it seems to me.

Worth a go if looks mean that much to you I suppose.

Why especially DO YOU want to keep the original look inside the engine bay? For one thing those saucepans make it more difficult to work on that side, I seem to remember from before I dumped mine.

As for fitting. The stacks use the same bolt holes as the saucepans. You can't use both, unless you modify the saucepans, and then they won't be original anymore, in which case you might as well remove them.😉
anamnesis

I confess I've no idea what a stub stack is. Does it improve air flow?
Bill Bretherton

Air flows more easily round a curve than a sharp edge is the way I understand it. Less turbulance. The carb mouth is a sharp edge. The stub stacks are rounded. They are stubs(short) because of the limited depth inside the filter.


anamnesis

Thanks, but the saucepans are rounded where the air enters so where is the sharp edge (given that the saucepans appear to bolt to the carbs "square on"?
Bill Bretherton

The sharp edge is where the saucepans bolt to the carb. Radiussing the intake tube to the saucepans is pointless. Vizard shows that a sharp edge to the carb reduces its effective diameter.

Les
L B Rose

How about welding two lengths of studding to the base of the air filter housing, then drill clearance and counterbored holes in the stub stacks and fix using nuts (and Loctite)?

Or do it the other way around: weld nuts to the filter housing base, then use screws (and Loctite) to attach the stub stacks to the nuts?

Either way, you just need to take care to make sure everything lines up - particularly the bore in the stub stack and the opening to the carb.

To get some extra air flow into the filters, can you add holes in the underside of the saucepans so they are not visible?

Have fun!
Jon
Jonathan Severn

The saucepan filters have (forgive the poor description) a long tube pipe that has a smaller opening then gets wider to the housing. As you can tell I can't remember the details (or correct words or description) but the size and length of the 'tube' IIRC was to give some effect to the air coming into the filter housing so putting additional holes in the filter housing might disrupt this effect. Part of it might be to also reduce noise but I don't know.
Nigel Atkins

Bill,
a (cheaper) example of the standard stub stack that usually goes with K&N pancake filters.

The very expensive double width K&N 'plate' filter that covers both carbs together have rounder style stub stacks cast into the backplate.



Nigel Atkins

Les, thanks.
Bill Bretherton

Bill,
I missed the edit as you posted. 😀

- The very expensive double width K&N 'plate' filter that covers both carbs together have rounder style stub stacks cast into the backplate - not the style of the one I put up in the photo.


Nigel Atkins

Thanks all, some good points.

The reason I want to keep the original filters is that I’m talking about my Mk1 midget which I’m trying to keep looking as standard as possible. I also have a well modified Sprite so it’s nice to have one I can modify to the max and one that at least looks standard!

The Mk1 actually has quite a few mods in that it is a 1275, has 10:1cr, a 256 cam, PB Econotune head and LCB. But I’ve tried to keep it looking nice and original under the bonnet, well at least to anyone other than a Midget spotter. Having had a car (the Sprite) with an ugly single HIF and modern K&N for so long it’s nice to have the twin SU’s and original filters - which I actually think look great.

So I have bought a pair of K&N elements (the correct Midget ones for the original housings) and now just want to optimise everything I’ve got. I might also do a bit of Vizardising of the carbs as Les mentions.

I’m happy to discreetly modify the housings (I’ve got a few to go at if it goes wrong!) and as Nigel and Jonathan mention, had thought of adding extra holes to allow more air in. Good point about that perhaps having a detrimental effect though. I haven’t really seen anything in Vizard about the flow of the pans. I’ve always thought they were designed to get cold air away from the exhaust and maybe the hole in each end is exactly the same as the carb at 1 1/4?

I’ve also got one of the big aluminium K&N filters with Midget cast into it which I’m sure are much better. These already have stub stacks cast into the backplate so it’s obvious that it must be something considered to work well. Unfortunately it’s not really the look I’m after as it’s a bit more 70’s than early 60’s!

Maybe I’m overthinking it and also trying a bit too hard for an extra 1-2bhp but I like getting the most I can out of things like that and it’s not really going to cost much to do. All good fun as well!




John Payne

Thanks Nigel, all makes sense now. I'm not into tuning as you might gather, I like the original exhaust note which is partly due to restrictions I guess.

Looks nice John. You even have the original looking hose clamps! I'm wondering whether to get those Coopers stickers.
Bill Bretherton

John,
an extra 1-2hp!?, well the rollers will tell, anyway the new rollers are now measuring in bananas and something else I forget and generally 7% less bananas IIRC.

I'm not sure the tubes are just to try to stretch to cooler air, see attached photo of Rover P6B air filter, small opening and pipe to big cannister with two paper filter elements, IIRC its design was all explained to me but I've forgot. In this case the opening is directly over the V8 engine and they can get quite warm.



Nigel Atkins

Bill,
you naughty boy, mentioning those Cooper sticks, and on those filter houses, you troublemaker, let things go. 🤣

John,
very smart, but lots of lost points for lack of oil leaks and signs of warranty repairs and servicing at dealerships. I could add a few spanner dinks and screwdriver scratches for you, and loosen the rocker cover, all for free out of the goodness of my heart.
Nigel Atkins

It is hard to correct all the small differences in diameter and line them up correctly: Engine, gasket, Inlet manifold, gasket, distance piece, gasket, heat shield, gasket, distance piece, gasket, carburetor, gasket, KN house, MED stub stack. And I can not feel the difference in HP or torque with and without the stub stack...

Flip
Flip Brühl

I believe Vizard tells all with regard to 1275 stub stacks. However I concur with Flip that it is difficult to get everything else to work with the stack in order for it to be of any benefit. You may get smoother flow/greater volumes of air in there - you may not. A dyno. should tell all, but I suspect that on a standard Midget carb. set up, the difference would be negligible. No harm in playing about of course.....all part of the enjoyment.
Oggers

Hi John

I have fitted the short K&N SU HS2 cast stub stacks shown above in Nigel’s post into the original saucepan filters for 948cc engined Mk11 Sprite and Mk1 Midgets. As Nigel says, they came with the K&N pancake filters. I used standard saucepan paper filters. I did switch out to using the K&N pancake filters as was setting car up and running a bit rich and got bored with taking the saucepans on and off, so refitted the K&N pancakes.

I did like your comment on how these filter housings will look more original to the casual observer - I feel all pointlessly anoraky noting the 1300 block rather than 948, later rocker cover and your early car would have had the breather connection from the rocker cover to the front saucepan and no PCV.

Looks great. Can we see the rest of the car please?

Cheers
Mike
M Wood

Funny you should mention the Cooper stickers (I’m not privy to the joke!) as I’m sure I’ve got them wrong somehow. I think there should be two different ones for front and rear pans, mine are both the same. Of course it’s only a point for the spotters and let’s face it the filter pans are completely wrong as they should at least be the rounded type.

That is exactly what I’m looking at Flip, in fact I think I’ll get one for my HIF on the Sprite, I’ve got a rolled aluminium Pipercross one in there at the moment.

Thanks Mike, good to know someone has done what I’m trying to do. I’ve seen the type you refer to so could at least go down that route if the solid ones don’t fit.

Of course there are lots of other points I’d lose out on in the concourse, no mechanical Rev counter, half GAN1 half GAN2 interior, no side strips (not plucked up the courage yet!) and numerous other things I’ve no doubt missed. I have got the correct rubber clip holding the choke cable to the heater though!

I’ll post a couple of photos for you in a mo.

John Payne

Couple of pics from last year:







John Payne

John,
it was a joke, I don't know but I think it might be the colour of stickers and there were different stickers later or before, I think, not sure, but as you say the saucepans mean it does matter anyway, not that it did matter anyway, well to me. I thought Mike might list a few more things too. 😁

Nice wheels mister, and hubcaps. 👍

I can see the rust rising off that grass, quick get it on the gravel.


Nigel Atkins

John

That is a very smart looking car and the light blue suits it very well. I still think round indicators/side lights would be a slight improvement though. The rectangles jar with the headlamps....
Oggers

John

That looks superb!

Keep your original parts in a box and keep with the car (Rev counter gearbox, correct saucepans etc)

Nigel, I was embarrassed enough to list a few things, without mentioning the saucepan top shapes, rev counter gearbox or the bonnet prop on the ‘wrong’ side.

John - I am with you in not wanting to drill to mount the Mk1 Midget side trim strips. If you want a period correct excuse, the BMC Competitions Dept did convert one of their three Mk1 rally Midgets to run as a Sprite, see the entry for YRX 734 at: http://www.jacobsmidget.com/worksrallycars.html Note all these cars were Tartan Red?

I think your car may be the same light blue colour (Ice Blue? Clipper Blue?) as the BMC works supported car of Tommy Gold (pic in the BMC Comps Book by Bill Price) that ran in the 1961 RAC rally (473 TEH).

My MkII Sprite has a Midget front wing on one side - I can tell as really badly filled holes in the outside that have sunk, plus a bit of MIG wire projecting through one filled hole!

Cheers
Mike


M Wood

The Gold owned car


M Wood

Mike, yes it’s Ice Blue, it left the factory with it - well not that actual paint!

Funny you should mention the bonnet prop, having fitted new wings and bonnet I had the choice of any of the options fitted over the years. The wings and bonnets produced now are made with all the different brackets fitted.
Having owned an original Mk1 a few years ago I didn’t want that option as the bonnet twists badly when propped up. So I went for the centre mounted option and it works perfectly.

Things like the bonnet prop are examples of why I got the car in the first place. It was a complete mismatch of years, no interior and no useable engine. It had been converted to discs and had run a 1275 and ribcase for many years. My old very original Mk1 was lovely to own but I couldn’t even make small alterations as it would have spoiled it. This car has given me the option to make a lot of changes to personalise it a bit and make it nicer to drive.

I probably will get round to fitting the side trims at some point (I have the new ones waiting) as I think it looks a lot better with them - as long as they all line up correctly!
John Payne

This thread was discussed between 16/05/2021 and 20/05/2021

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.