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MG Midget and Sprite Technical Presenting new member - and header question BBS discussion at MG-Cars.net
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MG Midget and Sprite Technical - Presenting new member - and header question
| Hello Gentlemen
I'm Jan, living in Denmark and a midget owner for a year. From many years of driving motorbikes, among them classics like Ariel, BSA and Triumph, as well as bikes from the "new" Triumph Hinckley factory, I like to have the head under the open sky. Getting more comfortable with the age I decided, for the first time, one year ago to try to own an classic car, an open one. I wanted it to be as small as possible to combine space awailable in the garage, cost of buying one, and the cost of spares if or when needed. I found a Brooklands Green MK III build June 1971 at Abingdon for the American market. It was reimported to Europe, Denmark, in 2007. I can do the mechanic work, but I can not do bodywork, so I needed a body with no rust and I knew I wanted a 1275. Last winther I gave the car a major overhaul, among the work done, was removal all the American "extras", the emission control system, and gave the engine the "European" approx. 9,3 CR pistons. It is a joy to ride and I like it better and better as I familarise with it. I have had great help from the North Ameican MG Experience forum, but I have missed an European forum, now I found it due to a hint from a UK member on the MG Exp. And the question: Why is a header a "must"? What can it do better than the cast manifold? Better flow? Thanks Jan |
| Jan Kruber |
| A wouldn't say it is a must, it all depends what state of tune your engine is in. An LCB manifold - we don't tend to call them headers on this side of the Atlantic - will flow better than the standard, cast manifold. Well, a good quality one will, anyway. There are plenty of people running with the standard manifold. Oh, and welcome to the best Midget and Sprite forum on the internet. |
| Dave O'Neill 2 |
| Jan Welcome to this great forum. I went to Copenhagen for the first time earlier this year and really enjoyed it except for the price of a cup of coffee! Also included a day trip to Malmo over the bridge. |
| Bill Bretherton |
| Jan There are many things you can do to improve performance before moving on to improving fluid flow at the exhaust manifold/header. It certainly is not a "must" and indeed, unless you have done other improvements to the engine beforehand, probabaly a waste of time to start there. |
| Oggers |
| Allright, than I suppose I'll just drive on with the stock manifold configuretion, since I believe the engine is stock. Dick can you please reveal to an ignorant what the Letters L B C stand for? Oh, and Bill, sorry about the expensive coffee, I regret you didn't visit Norway prior to visit Copenhagen, because then you would have considered the coffee and everything else to be very cheap :-) |
| Jan Kruber |
| hi all LCB long center branch ???? rgds tony b |
| tony boyle |
| Jan My philosophy is to try and perfect the current situation before spending lots of time and money on "improvements" Therefore, ensure the timing is correct, ensure all spark plugs are clean, ensure the mixture is correct, change the oil/filer/coolant if necessary, balance and bleed the brakes, carry out any maintenance due etc. |
| Oggers |
| Welcome Jan - I hope you enjoy life on four wheels---------------and a handbrake |
| William Revit |
| Wile I agree that getting the tune spot on is essential, the LCB maniofold presents a really useful gain on the Midget. It is not a matter of flow as such, but of separating the exhaust from the centre cylinders from that of the end cylinders for long enough to prevent backwash.
Explanation: Each time an exhaust valve opens there is a big pressure rise in the manifold ... a wave of pressure. This wave spreads out in all directions. In exactly the same way sound waves turn corners so we can hear something that's out of sight, so do these waves of exhaust gas. In aprticular, while a big chunk goes down the pipe as it should, it also spreads elsewhere in the manifold including up to and into the other cylinder branches. The exhaust valve opens before BDC, and by the time it is approaching BDC one of the other cylinders will be approaching TDC and the exhaust valve about to close. In a simple all-into-one-short-branch manifold like the standard Midget one, the pressure wave from the newly opened valve will reach the still-closing valve of one of the other cylinders and dump exhaust gas into it under pressure. This displaces fresh fuel/air charge, and can check the inlet flow as well. The longer the exhaust valve duration, the more marked the effect. If the manifold branches are made long enough, the pressure wave doesn't get into the port until after the other exhaust valve has closed - too late to do any damage. The affected cylinders are the ones half a rotation out of phase, so no's 1&4 affect no's 2&3 and vice-versa, but within each pair there's no problem as they are a complete rotation out of phase compared with each other. So it is not necessary to have all the manifold branches long enough, just the end ones separated from the centre two. Thank goodness or that centre siamesed port would be a real problem. So that's why the LCB is a really good idea, it improves torque right through due to preventing exguast backwash effectively reducing cylinder capacity. The MGB was one of the first production cars to adopt this mainfold format, sadly it was never done for the Midget despite having the same exhaust valve timing. The benefits are so marked that, despite the extra cost, it is now almost a universal design feature in cars for the last 30+ years |
| Paul Walbran |
| Nice Paul. That's about the clearest, most succinct precis of the benefits I've ever read. |
| Greybeard |
| Yes, Paul, that was educational. I always knew they were preferred, but never knew the details of why. And, welcome to Jan. Charley |
| C R Huff |
| I remember fitting an LCB to my standard 1.0 HLE Metro and it gave a useful gain in torque. On one long hill where before I had to change down to 3rd, after changing the manifold it romped up in top. Well much as a 50bhp Metro can 'romp' anyway! |
| John Payne |
| Paul
This was indeed very interresting reading. It just put things in place, thak you very much. So now I'm back where I started, I have considered to fit a suitable LCB for a stock 1275 engine - together with a new frontpipe and muffler. The reason: Last winther I discarded the present double cross over silencers, since there was no sound at all. Naturally I don't want a noisy car, but I like to hear the exhaust note, just a little. So I bought the single rear silencer at Moss and fitted it together with the old frontpipe and it sounds good, but it is a little to noisy on longer terms I think. So I would like it to be a little more silent. I know it's relative to discuss a noise level in written words, but do you guys have recommendations to a good LCB and a good silencer, or maybe adding a resonance muffler before the silencer. Jan |
| Jan Kruber |
| Jan a Maniflow LCB with an RC40 silencer gives a bassy sound- bit like a small MGB - not too loud for longer journeys but loud enough to enjoy. You can get it from Kim at http://www.magicmidget.co.uk which is where mine came from :) and I'm very happy with it! |
| Jeremy MkIII |
| If the engine is stock then I'd go for the roller tipped 1.5:1 ratio valve rockers Considering there is probably some wear on the valve gear and probably closer to 1.20:1 then factory 1.25:1 ... you would see some definate.. seat suck for what you will spend on a new manifold I'd pick up both Daniel Stapleton book and vizards bible on the midget and the 1275 Prop |
| 1 Paper |
| "On one long hill where before I had to change down to 3rd, after changing the manifold it romped up in top"
My wife had a Fiat Bambina with a primative exhaust, empty silencer into which the pipe went from each cylinder. But the ends of the pipes were blanked off, and the gas has to escape into the silencer via holes in the pipe walls inside the silencer. So I made up a good 2:1 system, and it found another gear too. Aided and abetted by going to 650cc, 10:1 CR and an MGB cam lobe profile. At one stage I also added a 45DCOE with one choke blanked off, just for the hell of it. It was half a 1275 after all, so I figured the size was about right. But the exhaust made the most difference. It was a fun rocketship (compared with expectations of such a car). Accelerated up hills in 3rd comfortably better than it went in 2nd when standard. Favourite party ricks: En route to home there is a long steep hill. Cars would pull out to pass this irritating little bit of Italian junk "holding them up" and be left struggling behind on the wrong side of the road as the bit of junk pulled away from them. (Loved doing that) Hillclimbed it once, upset all the std MGB drivers and challenged them to find their mojos. They did in the end, just, but it was a good stir up before they got there :-) Towed my dinghy & trailer to and from the beach, including up our 1 in 3 driveway. All came to an end when some oik nearly cut youngest son Cameorn in two when he was being picked up from kindergarten, but got the Fiat instead. Fixable, so sent to my mate the panelbeater where it has been ever since. Said son is now 27, must chase it up. But somehow I think the current supercharger into MGF project might take priority at present, getting closer so long as the Midgets continue to behave (he said, grabbing for some wood ... ) |
| Paul Walbran |
| Prop The rocker assembly was very worn so among other things done in the engine last winther I replaced it with a rebuild from Moss Europe. Had the cyl. head done too..... Actually there's not a spot in the engine not inspected and sorted out if nescessary when it was stripped down..... Jan |
| Jan Kruber |
| Jeremy I have contacted magicmidget to hear how they can help me. I read another thread here on the BBS about the difficulties in fitting the LCB with the engine allready in. Do you agree? Jan |
| Jan Kruber |
| Jan, that was me asking about fitting the Maniflow exhaust manifold. My one bought nearly 20 years ago wouldn't quite go in with the engine in place. From the answers l got l think they may have altered the design a little - just enough to make this possible now. I haven't ordered my new one yet, but when l do telephone them l will ask ! |
| GuyW |
| Guy, if I get a reply from Magicmidget and a recommendation what to acquire, I'll ask them about the fitting of the LCB. So if I'm first, I will let you know here what they say |
| Jan Kruber |
| What about this in stainless, certainly a very nice price: https://estore-sslserver.eu/twinkam.co.uk/epages/191f6b26-60bf-483c-b021-755a0c9099c1.sf/en_GB/?ObjectPath=/Shops/191f6b26-60bf-483c-b021-755a0c9099c1/Products/SC007 Anybody know of it, how it fits and so on? |
| Jan Kruber |
| Very little information there about it. I wonder what size pipe it fits? |
| GuyW |
| "We are extremely pleased to announce this superb T304 LCB manifold specifically designed for MG Midgets, A-H Sprites and other rear drive A-Series powered cars." I wonder which other cars it fits? A Spridget manifold won't fit a Minor or A35, for instance. |
| Dave O'Neill 2 |
| Arkley? And maybe they are including A+ engines? |
| GuyW |
| Guy, it says 42mm O/D and wall thickness of 1.2mm so 39.6mm internally which doesnt equate to an imperial sizes. Also I looked at them a while back and unless the photo misrepresents it the head fixings dont appear to line up. It is also stainless which Peter B has said previously, in his experience, can cause localised hotspots. Trev |
| T Mason |
| Thanks Trev, I couldn't see any sizes listed but maybe just missed a link? It is also claimed that SS manifolds resonate differently and give a tinny sound. The price listed excludes VAT so for the UK market that adds a fair bit so the price doesn't undercut Maniflow ones as much as would appear. |
| GuyW |
| As you say Guy, not much difference in price to Maniflow and you know what you are getting with them and as I said earlier I was put off by the mounting plates and holes looking like they were all over the place. Trev |
| T Mason |
| Btw Jan Just a heads up ... don't mention dead hookers in the trunk (boot) of the midget and how that can harm the value of the car with Trevor jessie It's very disturbing to sky, he takes that topic very seriously... experiance? Mg experiance? ... idk., you never know with snow shut in Canadians and the state of mind Prop |
| 1 Paper |
| Hello and welcome, Jan, to the site. As you can see, there is a wealth of information from others on here. Hope you'll stay around and your Midget sounds like a nice car. Prop, I thought Trevor Jessie was an American, and not from Canuckistan. (Canada) Cheers, Clare |
| Clare Ravenwood |
| Trevor is a kentukian. but sky the owne of the experisnce website is canadiadian |
| 1 Paper |
| Jan
Welcome. You may want to look on Maniflow's website for pictures and spec: http://www.maniflow.co.uk/index.php?view=category&category=206 (and exhaust: http://www.maniflow.co.uk/index.php?view=category&category=207) You may also want to consider a Maniflow exhaust too, or a Competition Silencers RC40. Advice available on this board, for example: http://www.mg-cars.net/mg-midget-sprite-technical-bbs/maniflow-lcb-att-onno-201409142325438981.htm http://www.mg-cars.info/mg-midget-sprite-technical-bbs/purveyors-of-decent-exhaust-system-201403011613432340.htm Cheers Mike |
| M Wood |
| Welcome Jan, I have had several stainless exhausts. I did not like the note. I replaced my old Maniflow LCB by a new over the axle one recently. It fits perfect, no bending and no welding necessary. The over the axle silencer is shorter and louder over 4 000 RPM. It gives more room for the Panhard rod. I prefer a small extra silencer (photo) in front of the short one for long journey's. An other advantage: The LCB does not crack on speed humps. I ordered direct from Maniflow. Flip  |
| Flip Brühl |
| I disagree somewhat with Paul.
Of more importance is the arrival of the low pressure wave caused by the exhaust valve closing - ideally at the time that the next exhaust valve is opening - but since the length of manifold is fixed and the pulses vary with engine speed, the effect is only true in a limited rev range as is the high pressure pulse. The key to good manifold design is to get that range where it is going to be useful - 6000 rpm is great for racers but 2000 rpm is more use to road drivers. Contrary to general opinion some short manifolds like the MGA 3 into 1 with a single downpipe actually produces MORE power in the mid range than the MGB standard 4 into 2 into 1 design. Cast iron manifolds are also quieter and don't warp like tubular headers and whatever you do, don't wrap a tubular manifold, it makes them warp even more and increases the head temperature which is neither good for the cooling system nor the temp of the intake charge in the neighbouring ports. |
| Chris at Octarine Services |
| Get a reply from Magic Midget: Hi Jan, Apologies I no longer have the RC40 exhaust systems. I keep the maniflow single box exhaust system, which is very similar, although its probably going to give the same sort of noise, especially if you use the LCB manifold as well. In mild steel the manifold is £150 and the system £140. regards Kim Dear |
| Jan Kruber |
| Filip, Is the silencer on your picture the one that Maniflow sell as: SPRIDGET (OPTIONAL) BULLET SILENCERS (SB031/32/33 ? |
| Jan Kruber |
| just a message of Welcome Jan. Good luck with your improvements to your car. Do please share your progress, your highs and lows so we can all follow and learn at the same time.... |
| P Bentley |
| The low pressure wave following on down the exhaust pipe behind the 'slug' of exhaust from one valve opening, helps to pull the next gasp of exhaust through. If you like, the low pressure provides space for the next wave to go into. This is dependant on revs, and in having a sufficient length of pipe before the pressure gets compromised by pressure waves from the other cylinders. Vizard (l think) claims that a true LCB manifold suits the small capacity A series better than the 1275s. |
| GuyW |
| You might look at cheery bomb mufflers they are compact and go over the axle also and give a nice racer sound
Also motor cycle mufflers such as harly Davidson are always talked about as an option If you do a tubular header... have it ceramic coated , esp inside and outside if you like It's more important inside the header as the heat won't soak into the metal as easily and the heat will be forced out the pipe rather then thud thr the header metal...but the header needs to be new for the ceramic to stick long term I have a 3 into 1 for my 1275 and love it exception July and August when the outside temps are 100F plus Consider thinking about wing heat vents to djsspell the heat build up in the engine bay from the header |
| 1 Paper |
| RC40 rear box and fitting kit available from Minispares: https://www.minispares.com/shop/classic/Exhaust~and~manifold/RC40~Classic~range.aspx?1105 See Alex's post on fitting this at: http://www.mg-cars.net/mg-midget-sprite-technical-bbs/silencer-2011082915415724011.htm http://www.mg-cars.net/mg-midget-sprite-technical-bbs/rc40-twin-tail-pipes-2014082109301427260.htm Cheers Mike |
| M Wood |
| Mike, Can I e-mail you "off list" please? Guy AT Weller-lakes DOT Co DOT uk |
| GuyW |
| Found this: http://www.calverst.com/technical-info/exhausts-rc40-millennium-and-others-tested/ |
| Jan Kruber |
| This thread has been really interesting, and it's made me wonder whether the 1980 manifold that came with the car might be better than the Maniflow I put on nearly 15 years ago. With a 948 engine, is a large diameter tube better? Or might it be counter-productive?
The old one pictured (some of you will have seen it before) is slightly smaller (haven't measured yet) but has the advantage of joining branches just above the hole in the rail - which required enlarging for a Maniflow - plus the centre branch runs smoothly beneath the heat shield without the need to hammer a bulge. Admittedly the face apertures are round rather than rectangular, but big enough, I think. I will measure tomorrow.  |
| Nick and Cherry Scoop |
| Nick, if that manifold has circular ports, it could well be a Speedwell manifold. I had one a few years back. I also have an original Speedwell manifold gasket. The Speedwell alloy heads had circular exhaust ports. Here's a pic of a head courtesy of CCK Historic.  |
| Dave O'Neill 2 |
This is the manifold that I sold nearly ten years ago.
 |
| Dave O'Neill 2 |
Look familiar?
 |
| Dave O'Neill 2 |
| Very close, Dave. Handmade stuff, presumably, so maybe a Speedwell from a different week's production.
I replaced it all those years ago without even having driven the car on the old manifold, because I was keen and had some money from somewhere I suppose. But now that I look more closely, the Speedwell has the same ID (31mm) and the only other differences are the MF's large rectangular face ports, the point of joining, the centre branch bulge and larger centre branch diameter (37 OD against 33 OD for the side branches). I would be very interested to hear what the experts say about the likely performance differences, if any.  |
| Nick and Cherry Scoop |
Here's head port to manifold port. Not bad.
 |
| Nick and Cherry Scoop |
This thread was discussed between 11/11/2017 and 17/11/2017
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